A Scoping Review and Practical Approach to Measuring Health Literacy in Solid Organ Transplantation

Abstract

Introduction: Solid organ transplant recipients have extensive self-care responsibilities. Limited health literacy (HL) can hinder effective self-management and long-term outcomes. Objective: A scoping review of HL instruments is needed to summarize their use in solid organ transplant. Methods: A systematic search was conducted using Medline, Embase, and CINAHL databases to identify studies that measured HL in the context of solid organ transplant. Search results were uploaded into Mendeley, and duplicates were removed. Two reviewers screened the abstracts and full texts for eligibility and discrepancies were resolved by the research team. Data extraction included publication details, study features, and HL instruments. Results: Of 721 articles identified for title and abstract assessment, 94 articles were further reviewed for full-text eligibility, and 50 were included in the review. HL instruments included: the Brief HL Screen (BHLS) and iterations (with 16 studies), Newest Vital Sign (NVS) (15 studies), Rapid Estimate of Adult Literacy in Medicine (REALM) (8 studies), Test of Functional HL in Adults (TOFHLA) (7 studies), HL Questionnaire (HLQ) (6 studies), eHL Scale (eHEALS) (4 studies), Brief Medical Numbers Test (BMNT) (3 studies), Decision-Making Capacity Assessment Tool (DMCAT) (2 studies), Short Assessment of HL (SAHL) (1 study). Discussion: Seven studies used multiple HL instruments in their analysis. Some instruments had multiple versions, such as the original TOFHLA and its shortened form (S-TOFHLA), and the original REALM and its transplant-specific version (REALMT). Conclusion: This review provides an overview of HL instruments for transplant healthcare providers who may want to incorporate HL measurement into practice.

Introduction

Health literacy (HL), which is the ability to obtain, understand, and use health information to make informed decisions about one's health, is extremely important in the context of solid organ transplantation. ¹ Throughout the transplant journey, patients must be able to utilize health information to navigate health systems, attend medical appointments, and maintain testing and diagnostic schedules, and other required services. Patients must comprehend, assess, communicate, and apply health information to make informed decisions about their care. Posttransplant care involves complex self-management tasks, including symptom monitoring, infection prevention, and maintaining a healthy lifestyle. Notably, the Centers for Disease Control and Prevention (CDC) has recently defined “organizational HL” as “the degree to which organizations equitably enable individuals to find, understand, and use information and services to inform health-related decisions and actions for themselves and others.” ² This new definition emphasizes the need for people to use and apply health information rather than just understand it and acknowledges that organizations have a responsibility to address HL. ²

Adequate HL is essential for utilizing health information. Limited HL has been consistently associated with negative health outcomes both in the general population and in transplantation.^3–8 Individuals who struggle to understand health information experience higher rates of hospitalization and increased use of emergency room services. They also have a higher risk of drug- and disease-related complications and difficulty engaging in disease-preventative strategies.^4–6 In transplantation, lower HL has been associated with increased creatinine levels,^7,8 more hospitalizations and readmissions,^9,10 and an increased risk of graft failure. ¹⁰ People with poor HL are also less likely to be waitlisted for transplant.^10,11 Unfortunately, limited HL is highly prevalent, affecting as many as 72% of patients with solid organ transplant. ³

Identifying people at risk of limited HL is challenging, and healthcare providers routinely overestimate their patients’ comprehension. ¹² Demographic risk factors such as age, race/ethnicity, education level, and economic status are associated with limited HL, but relying exclusively on such characteristics can lead to incorrect assumptions. Several instruments have been developed to assess HL, ⁴ but the use of these instruments within a solid organ transplant context has yet to be explored. Previously published views have focused on instruments used in other disease states. Measuring HL has several potential applications. In a clinical setting, identifying specific patients at risk of limited HL could direct healthcare providers to provide additional support and tailor communication strategies accordingly. From a public health perspective, determining the HL at a population level could help inform promotion strategies. Measuring HL has been of utility in research, both as an outcome measure and as an important demographic variable.

Objective

Given this context, the purpose of this review is to address a critical gap in transplantation literature: while the impact of HL on outcomes is well recognized, there is limited awareness of the wide range of instruments available to measure HL and their varying characteristics. This scoping review summarizes how HL instruments have been applied in solid organ transplantation and provides a practical overview to guide clinicians and researchers in selecting appropriate measures for clinical and research settings.

Methods

Design

A scoping review was conducted to explore the existing literature on HL measurement in solid organ transplant recipients. The research question was framed using the PCC (population, concept, context) framework recommended for scoping reviews: population, solid organ transplant recipients (including pretransplant and posttransplant populations); concept, HL measurement instruments; context, any setting within transplantation (eg, clinical or research). A scoping review approach was chosen because the objective was to map the breadth and characteristics of existing literature on HL measurement in solid organ transplantation rather than to evaluate intervention effectiveness or synthesize outcomes. Scoping reviews are valuable for summarizing a wide range of literature, mapping available evidence, and identifying gaps in knowledge.

To identify the relevant literature for the review, a systematic search was conducted using 3 different databases: Medline, Embase, and CINAHL. The search strategy was developed and reviewed with a medical librarian to ensure completeness and accuracy. While the PRESS (Peer Review of Electronic Search Strategies) checklist was not explicitly documented, the review followed best practices consistent with PRESS principles. No supplementary search techniques (such as citation searching, manual review of key journals, or contacting experts) were performed beyond the database search. Terms related to the categories of HL, medical and medication literacy, and transplantation were used in the search. Boolean operators such as AND/OR were utilized to connect the categories. The search took place in August 2024. The comprehensive search strategies are provided in Appendix A.

Studies were eligible for inclusion if they were original articles published and written in English and measured HL in the context of solid organ transplant. The following articles were excluded: (1) case reports, book chapters, letters, editorials, abstracts; (2) studies that did not specify what instrument they used; (3) protocols that were later published with results available; (4) and studies that were not available in English. This scoping review was not prospectively registered.

Data Collection

Search results were compiled into Mendeley, and titles and abstracts duplicates were removed by VP. Full texts were retrieved for abstracts that passed the initial screening and were assessed for eligibility based on the inclusion and exclusion criteria by VP and BM. Any discrepancies between reviewers were resolved through discussion, and when consensus could not be reached, a third reviewer (HM) made the final decision.

The full breakdown of the article selection process is available in Figure 1. A data extraction tool was developed by VP and HM and was piloted with a sample of 5 articles. Refinements were made to the tools before proceeding with the full data extraction (performed by VP and BM and then reviewed by HM). Relevant data were captured in a data collection tool in Microsoft Excel (Version 16.9) and then summarized into tables. Once the transplant literature was identified, the screening tool was researched further, and original validation studies were reviewed. During data collection, articles were initially categorized according to the instrument name reported in each manuscript. After completion of data extraction, these categories were consolidated under their core instrument family to ensure consistency and avoid classification inconsistencies (eg, Brief Health Literacy Screen [BHLS], Subjective Health Literacy Screener [SHLS], and Short Literacy Survey [SLS] grouped).

Figure 1.

Flowchart for identification of relevant studies.

Outcome Measures

Extracted data included (1) publication details, including author and year; (2) study features, such as country, setting, population, participant count, and HL outcomes; and (3) HL instruments, including details regarding their name, dimensions, number of items, purpose, target audience, administration method, validation process, scoring system, cutoff points, and their strengths and limitations. Tables were compiled to provide a description of how and when the instruments were developed (Table 1), further describe the instruments’ characteristics (Table 2), review studies of the instruments used in transplants (Table 3), and provide a summary of the measures, including strengths and limitations for healthcare providers potentially considering their use in transplant (Table 4). Table 5 summarizes which HL instruments assess key domains such as numeracy, comprehension, digital HL, and functional HL, with the following definitions applied: numeracy = the ability to understand and apply numerical information in health contexts, such as medication dosing or interpreting laboratory values; comprehension = the ability to read, interpret, and understand written or spoken health information; digital HL = the ability to seek, find, evaluate, and use health information from electronic sources and digital tools; functional HL = basic reading, writing, and numeracy skills required to function effectively in healthcare settings, including understanding prescriptions, appointment instructions, and consent forms.

Table 1.

Development of HL Assessment Instruments.

Short Name	Full Name	Who Developed the Instrument/Year of Publication	Where was It Developed/Target Population	Purpose	Validation (Original Study)
BHLS	Brief HL Screen/Short Literacy Survey	Chew et al, 2004, 14 developed an original questionnaire (3 questions).	United States/preoperative adults at a Veterans Affairs clinic	A practical method for identifying patients with self-reported low HL	- Reliability: Cronbach's alpha = .76Items were effective in detecting inadequate HL when tested against S-TOHFLA; AUROC curve ranged from 0.76 to 0.87 (95% CI). Items were weaker at detecting inadequate/marginal HL.
SILS	Single-Item Literacy Screener	Morris et al 2006 16	United States/adults (18 years old) with diabetes	Identify patients who have difficulty with a central aspect of HL (reading health-related materials)	Items were effective in detecting limited HL when tested against S-TOHFLA “limited reading ability” (0-22 correct answers) or were unable to take the test because of visual or other impairments; AUROC was 0.73 [95% CI 0.69-0.78]
SHLS	Subjective HL Screener	Chew et al. 2008 15	United States/adults attending a visit at a Veterans Affairs clinic	Evaluated 3 single-item screening questions in assessing HL	Items detected inadequate HL when tested against S-TOFHLA (AUROC = 0.66-0.74) and REALM (AUROC = 0.72-0.84). “Confidence with forms” question performed significantly better than the other 2 questions (P < .05).
BRIEF	Brief HL Screening Tool	Haun et al, 2009, 26 added a 4th question and called it BRIEF	United States/adults attending a visit at a Veterans Affairs clinic	Aimed to improve the ability to detect inadequate/marginal HL	Pearson correlation results were r = 0.40 (P < .01) for the BRIEF and the REALM; r = 0.42 (P < .01) for the BRIEF and the S-TOFHLA; and r = 0.61 (P < .01) for the REALM and the S-TOFHLA.
EBHLS	Expanded Brief HL Screen	San-Jecklin et al, 2014, added a 5th question (EBHLS) 27	United States/adults attending primary care clinics	Added 2 questions to assess understanding and remembering health information	- Reliability: Cronbach's alpha = .79- Correlation with S-TOFHLA scores, with higher correlations between BHLS items addressing written HL and the S-TOFHLA
BMNT	Brief Medical Numbers Test	Developed by Miller-Matero et al 2015 28 (validated by Dykhuis et al 2019 17 )	United States/presurgical evaluation for transplantation	Quickly assess the health numeracy of a patient during presurgical txp evaluations	- Reliability: Cronbach's alpha = 0.71- Correlation with REALM-R (r = 0.28), REALM-SF (r = 0.26), and MoCA (r = 0.49) (P < .01)
DMCAT	Decision-Making Capacity Assessment Tool	Kazley et al 2014 18	United States/patients with ESRD or kidney txp	Measure knowledge of ESRD terminology and capacity to navigate the process	- Correlation with REALM-T (r = 0.401) and NVS (r = 0.727)- Test–retest (κ = 0.65) and inter-rater reliability (weighted κ = 0.71) acceptable
eHEALS	eHL Scale	Norma and Skinner 2006 19	Canada/youth (13-21 years old)	Assess perceived skill at using technology for health	- Reliability: Cronbach's alpha = .88- Test–retest ICC (r = 0.49), suggesting moderate stability
HLQ	HL Questionnaire	Osborne et al 2013 20	Australia/general population	Instrument to detect a wide range of HL needs in individuals and organizations	9-factor CFA model fit (44 items) with no cross-loadings or correlated residuals. Satisfactory fit: CFI = 0.936, TLI = 0.930, RMSEA = 0.076, WRMR = 1.698
NVS	Newest Vital Sign	Weiss et al 2005 21	United States/adults (18 years old) English and Spanish speaking	Quick screening test for limited literacy and numeracy using a nutrition label	- Reliability: Cronbach's alpha: E-NVS 0.76, S-NVS 0.69- Correlation with TOFHLA (E-NVS r = 0.59; S-NVS r = 0.49); AUROC curve was 0.88 for E-NVS and 0.72 for S-NVS.
REALM	Rapid Estimate of Adult Literacy in Medicine	Davis et al, 1991, 29 published the original version with 125 words, shortened by Davis et al in 1993. 22	United States/adults (18 years old)	Provide physicians with an estimate of patient literacy using the reading level	- Correlation with SORT-R (r = 0.96), PIAT-R (r = 0.97), and WRAT-R (r = 0.88) (P < .0001)
REALM-T	Rapid Estimate of Adult Literacy in Medicine—Transplantation	Gordon and Wolf 2009 8	United States/adult (18 years old) kidney txp recipients	Provide physicians with an estimate of patient literacy using terms that kidney txp recipients should know	- Reliability: Cronbach's alpha = .94- Correlation with S-TOFHLA: r = 0.46, P < 0.001
SAHL-S&E	Short Assessment of HL—Spanish and English	Lee et al 2010 23	United States/adults (18-80 years old)	Create an instrument for HL in Spanish- and English-speaking populations	- Reliability: Cronbach's alpha = Spanish .80, English .89- Correlation with TOFHLA (Spanish version, r = 0.62; English version r = 0.68) and REALM (r = 0.94)
TOFHLA	Test of Functional HL in Adults	Parker et al 1995 24	United States/adults (18 years old) outpatient setting in public teaching hospitals	An instrument that measures functional HL of patients using health-related content	- Reliability: Cronbach's alpha = English .98, Spanish .98- Concurrent validity (English): correlation with REALM (r = 0.84) and WRAT-R (r = 0.74)
S-TOFHLA	Short Form—Test of Functional HL in Adults	Baker et al 1999 25	United States/adults (18 years old) urgent care center and medical clinic	Abbreviated version of the TOFHLA	- Reliability: Cronbach's alpha = .97 (reading comprehension), .68 (numeracy)- Reading comprehension correlation with REALM: (r = 0.80), reading numeracy (r = 0.61)

Abbreviations: AUROC, area under the receiver operating characteristic; BHLS, Brief Health Literacy Screen; BMNT, Brief Medical Numbers Test; BRIEF, Brief Health Literacy Screening Tool; CFA, confirmatory factor analysis; CFI, comparative fit index; CI, confidence interval; DMCAT, Decision-Making Capacity Assessment Tool; eHEALS, eHealth Literacy Scale; E-NVS, New Vital Signs English version; ESRD, end stage renal disease; HL, health literacy; HLQ, Health Literacy Questionnaire; ICC, intra-class coefficient; MoCA, Montreal Cognitive Assessment; NVS, New Vital Signs; PIAT-R, Peabody Individual Achievement Test—Revised; REALM, Rapid Estimate of Adult Literacy in Medicine; REALM-R, Rapid Estimate of Adult Literacy in Medicine—Revised; REALM-SF, Rapid Estimate of Adult Literacy in Medicine Short form; REALM-T, Rapid Estimate of Adult Literacy in Medicine—Transplantation; RMSEA, root mean square error of approximation; SAHL-S&E, Short Assessment of Health Literacy—Spanish and English; SILS, Single-Item Literacy Screener; SHLS, Subjective Health Literacy Screener; S-NVS, New Vital Signs Spanish version; SORT-R, Slosson Oral Reading Test-Revised; S-TOFHLA, Short Test of Functional HL in Adults; TLI, Tucker–Lewis index; TOFHLA, Test of Functional Health Literacy in Adults; txp, transplant; WRAT-R, Wide Range Achievement Test—Revised; WRMR, weighted root mean square residual.

Table 2.

Characteristics of Health Literacy Assessment Instruments.

Short Name	Description/Type of Measurement	Items, Questions, or Domains	Scoring and Thresholds	Administration Time	Mode of Administration	Other Translated Versions Available a ,30,31
BHLS/SHLS/SILS/BRIEF/EBHLS	Questionnaire	The original version 14 had 3 questions: “How often do you have someone help you read hospital materials?” “How often do you have problems learning about your medical condition because of difficulty understanding written information?” “How confident are you filling out medical forms by yourself?” (referred to in literature as BHLS or SLS).1 question tested was by Morris et al 16 (“How often do you need to have someone help you when you read instructions, pamphlets or other written material from your doctor or pharmacy?” Referred to as SILS.3 questions were again tested by Chew et al 15 (SHLS), but they found the “confidence with forms” question performed best.The 4th question was added by Haun et al (BRIEF) 26 :“How often do you have a problem understanding what is told to you about your medical condition?”A 5th question was added by Sand-Jecklin et al (EBHLS) 27 : “How often do you have difficulty remembering health information and instructions from your healthcare provider?”These questions assess confidence with reading and understanding health materials	Questions are scored on a 5-point Likert scale. Score range: 3 to 15 or 0 to 12 depending on how the Likert scale is coded (0-4 or 1-5).Higher scores demonstrate better HL.Scores over 2 were used to define limited HL in the 3-question version.	1 to 2 min	Self-administered or interview	EnglishSILS in Arabic, ItalianBHLS in Spanish
BMNT	Test	4 items designed to evaluate mathematical skills: eg, “Your doctor says you need 64 ounces of water each day. A cup is 8 ounces. How many cups do you have to drink each day?”Health numeracy	Questions are scored as correct, incorrect, or incomplete.Even 1 incorrect item indicates a potential need for additional support.	2 to 3 min	Self-administered	English
DMCAT	TestOpen-ended questions	7 questions based on a kidney failure scenario.Survey administrator reads a scenario about a person with symptoms common to ESRD and asks follow-up questions that require patients to make a decision.Assesses knowledge of dialysis and txp process and decision-making.	Questions are scored from 0 to 3 (0, incorrect/no answer; 1, vague/nonspecific response; 2, good but limited response; 3, good comprehensive response).Score range: 0 to 21.No set cutoffs for good or poor literacy.	Not specified	Administrator required	English
eHEALS	Questionnaire	8 questions that assess combined knowledge, comfort, and perceived skill at finding, measuring and applying electronic health information to health problems.	Questions are scored on a 5-point Likert scale.No set cutoffs for good or poor literacy.Higher scores represent higher self-perceived HL.	Not specified	Self-administered or interview	English
HLQ	Questionnaire	44 questions and 9 domains: (1) feeling understood and supported by HCP, (2) having sufficient information to manage health, (3) actively managing health, (4) social support for health, (5) the appraisal of health information, (6) ability to actively engage with HCP, (7) navigating the healthcare system, (8) ability to find good health information, (9) understanding health information well enough to know what to do	The first 4 domains are scored on a 4-point Likert scale, while the last 5 domains are scored on a 5-point Likert scale.Scores are averaged for a mean score per domain.Higher scores indicate higher HL, but there are no set cutoffs for good or poor literacy.	20 to 30 min	Self-administered or interview	English, Korean, German, Danish, Slovakian, Dutch, Iranian, Norwegian, Ghanaian, Chinese, Urdo, Yoruba, Brazilian, Brazilian-Portuguese, French
NVS	TestOpen- and closed-ended questions	Uses an ice cream nutrition facts label and a series of 6 questions about how the individual would act on and interpret the information provided on the label.Assesses comprehension of information and health numeracy.	Scores are based on the number of correctly answered questions:0 to 1 correct answers indicate high likelihood of limited HL; 2 to 3 = limited HL; 4 to 6 = adequate HL.	3 to 5 min	Administrator required	English, Spanish, Dutch, Japanese, Italian, Arabic, Brazilian Portuguese, Turkish, Taiwanese American Sign Language
REALM/REALM-T	Test	Individuals are asked to read through lists of words, which indicates the ability to correctly pronounce a list of words.REALM = 66 words; REALM-T = 69 words.Assesses word recognition and pronunciation.	Scores are determined based on the number of correctly pronounced words.Scores are grouped accordingly into categories of adequate, marginal, and inadequate HL or estimate of literacy grade level: (0-18) 3rd grade and below; (19-44) 4th to 6th grades; (45-60) 7th to 8th grades; (61-66) 9th grade and aboveREALM-T: inadequate = 0 to 44; marginal = 45 to 59; adequate = 60 to 69.	2 to 3 min	Administrator required	English, Korean, Spanish, Arabic
SAHL-S&E	TestMultiple choice, word pronunciation	Individuals are asked to read a medical term and then make associations with similar terms.18 questions to determine an individual's ability to correctly pronounce and choose related terms.Assesses comprehension, word recognition, and pronunciation.	Each correct word is 1 point.Scores of 0 to 14 indicate inadequate HL.	2 to 3 min	Administrator required	English, Portuguese, Brazilian Portuguese
TOFHLA/S-TOFHLA	TestMultiple choice	2 sections, 67 itemsSection 1: 50-item reading comprehension test. 3 real-world prose passages from healthcare settings are used, and participants are required to select the word that best fits the blank space in the statement.Section 2: 17-item numeracy test. Patients are given cue cards or prescription bottles and asked questions about the information.Assesses comprehension of information, numeracyS-TOFHLA: 40 items. The TOFHLA was reduced to 2 prose passages and 4 numeracy items.	Points are awarded for each correct answer and are converted to a score.TOFHLA inadequate health literacy = 0 to 59; marginal = 60 to 74; adequate = 75 to 100.S-TOFHLA inadequate = 0 to 16; marginal = 17 to 22; adequate = 23 to 36.	TOFHLA = 22 minS-TOFHLA = 7 min	Administrator required	English, Spanish, Chinese, French, German, Italian Serbian, Danish, and Albanian, Turkish, Hebrew

Abbreviations: BHLS/SLS, Brief Health Literacy Screen/Short Literacy Survey; BMNT, Brief Medical Numbers Test; BRIEF, Health Literacy Screening Tool; DMCAT, Decision-Making Capacity Assessment Tool; eHEALS, eHealth Literacy Scale; ESRD, end-stage renal disease; HCP, healthcare provider; HL, health literacy, HLQ, Health Literacy Questionnaire; NVS, New Vital Signs; REALM, Rapid Estimate of Adult Literacy in Medicine; REALM-T, Rapid Estimate of Adult Literacy in Medicine—Transplantation; SAHL-S&E, Short Assessment of Health Literacy—Spanish and English; SHLS, Subjective Health Literacy Screener; SILS, Single-Item Literacy Screener; S-TOFHLA = Short Test of Functional Health Literacy in Adults; TOFHLA, Test of Functional Health Literacy in Adults; txp, transplant.

a

Information also obtained from previous health literacy reviews^30,31

Table 3.

Summary of Quantitative Health Literacy Assessment Studies in Organ Transplantation.

Author, Year of Publication	Title	Location/Organ Population	Study Description and Outcome Measures	HL Results
BHLS/SILS/SHLS/BRIEF/EBHLS
Dageforde et al 2014 40 (BHLS/SHLS)	Health Literacy of Living Kidney Donors and Kidney Transplant Recipients	United States/living kidney donors and txp recipients(n = 360)	Assessed associations of patient and demographic characteristics with HL in a retrospective chart review (BHLS)	HL scores were 49%, 41%, and 10% for high, moderate, and low HL categories, respectively. After age, race, sex, and education were controlled for and race–education interaction term decreased, deceased donor recipients were more likely to have low or moderate HL than live donor recipients (P = .022).
Dageforde et al 2015 47 (BHLS/SHLS)	Understanding Patient Barriers to Transplant Education	United States/patients being evaluated for kidney txp (n = 104)	Evaluated demographics, socioeconomic factors, and HL factors among patients who did and did not attend transplant referral visits. Survey-based study conducted via phone interview (BHLS)	77% of patients had adequate HL. There was no difference in HL scores between those who did and did not attend the transplant referral visits.
Taylor et al 2016 48 (SILS)	Limited Health Literacy in Advanced Kidney Disease	United Kingdom/dialysis, kidney txp, and kidney txp waitlisted patients(n = 6842)	Investigated the prevalence and associations of limited health literacy at various stages of treatment. Retrospective analysis of data from the United Kingdom–wide Access to Transplantation and Transplant Outcome Measures (ATTOM) program (SILS)	Limited HL (>2 SILS) was prevalent in the following: 20% incident initiation, 15% incident kidney txp waitlist, and 12% incident kidney txp groups. Dialysis patients had significantly lower HL than patients on the waitlist (P < .001). Preemptive live-donor txp had higher HL than deceased donor recipients did (P = .002).
Cajita et al 2017 49 (BHLS/SHLS variant)	Health Literacy in Heart Transplantation: Prevalence, Correlates and Associations with Health Behaviours—Findings from The International BRIGHT Study	International/heart txp recipients(n = 1365)	Secondary analysis of the BRIGHT study to compare the prevalence of inadequate HL among heart txp patients internationally and determine the correlates (single-item version of SHLS “confidence with forms”)	33.1% had inadequate HL. Factors associated with inadequate HL were lower education level (aOR 0.24; P < .001), unemployment (aOR 0.69; P = .012), and country (ie, Brazil) (aOR 0.25; P < .001). Those with adequate HL were more likely to engage in sufficient physical activity (aOR 1.6, P = .016). HL was not associated with other health behaviors.
Weng et al 2017 41 *Also in NVS	A Clustered Randomized Trial of an Educational Intervention During Transplant Evaluation to Increase Knowledge of Living Donor Kidney Transplant	United States/patients being evaluated for kidney txp(n = 499)	Tested the effectiveness of a 1-time educational intervention among patients who presented for evaluation of a kidney txp vs usual-care education to assess efficacy of the educational intervention	Used HL as a variable and descriptor of the patient population. Found that most participants were extremely confident filling out medical forms by themselves (58.6%) and had the highest score category on the NVS (75.2%)
Taylor et al 2019 50 (SILS)	Limited Health Literacy Is Associated with Reduced Access to Kidney Transplantation	United Kingdom/dialysis patients(n = 2274)	A prospective cohort study to identify independent associations between HL and clinical outcomes, including access to kidney transplantation (SILS)	359 patients had limited HL. Limited HL was associated with reduced likelihood of being listed for a deceased-donor txp (HR 0.68; 95% CI 0.51-0.90) or receiving a live-donor txp (HR 0.41; 95% CI 0.19-0.88) and deceased-donor txp (HR 0.65; 95% CI 0.44-0.96) (P < .001).
Warsame et al 2019 34 (BHLS/SHLS)	Limited Health Literacy and Adverse Outcomes Among Kidney Transplant Candidates	United States/patients being evaluated for kidney txp(n = 1578)	A prospective longitudinal study to examine whether limited HL is associated with listing for transplantation and to quantify the association between limited HL and waitlist mortality (BHLS)	8.9% of candidates had limited HL (defined as <5 points on the BHLS). Candidates who had limited HL were more likely to be African American, to be male, and to have higher scores on the Charlson comorbidity index. Participants with limited HL had a 30% decreased likelihood of listing. The risk of waitlist mortality was greater among those with limited HL (1- and 2-year mortality among those with limited HL was 8.2% and 22.2%, respectively, as compared to 2.6% and 8.3% among those with adequate HL).
Tan et al 42 2020 (BHLS/SHLS)	Waitlisted Transplant Candidates’ Attitudes and Concerns Toward Transplantation During COVID-19	Singapore/patients awaiting solid-organ txp and hematopoietic stem cell txp(n = 71)	Standardized phone survey assessed if inadequate HL impacted opinions on txp during the pandemic (BHLS)	47.9% were classified as having inadequate HL. Inadequate HL was associated with older age (P = .003), lower education (P = .001), and a higher number of children (P = .001). There were no differences between sex (P = .76) or txp type (P = .06). There were no differences between HL scores and thoughts on txp during the pandemic.
Lorenz et al 2022 11 (BRIEF)	The Relationship Between Health Literacy and Outcomes Before and After Kidney Transplantation	United States/patients evaluated for kidney transplant(n = 690)	Examined the relationship between HL (4-item version) and rates of waitlisting in kidney txp candidates (BRIEF)	The prevalence of limited, marginal, and adequate HL among patients was 9.4%, 21.0%, and 69.6%, respectively. Patients with limited or marginal HL were significantly less likely than patients with adequate HL to be waitlisted (HR 0.62; 95% CI 0.44-0.88; P = .004 and HR 0.69; 95% CI 0.54-0.88; P = .003).
Tang et al 2023 51 (SILS)*Also in eHEALS	Patients’ Perspectives, Factors, and Patterns of eHealth Use in Kidney Transplant Recipients	Australia/kidney txp recipients(n = 91)	Cross-sectional survey with free responses to determine factors associated with eHealth use, attitudes, and perspectives (SILS)	Approximately 30% reported adequate eHealth literacy (eHEALS >32). Mean eHEALS score was 28.10, and SILS score was 1.77. Higher eHEALS scores were associated with higher eHealth use and tertiary education. Among noncurrent eHealth users, most were aware of eHealth and were willing to use eHealth in the future.
Kayler et al 2019 52 (BHLS/SHLS)	Development and Preliminary Evaluation of ilearnKAS: An Animated Video About Kidney Allocation to Support Transplant Decision-Making	United States/kidney txp candidates(n = 50)	This pre–post study aimed to develop a feasibility test and educational video culturally targeted to African-American patients regarding kidney allocation.	22 patients were deemed to have low literacy. Larger effects were seen between pre and post video knowledge in low-literacy groups (r = 0.6, P = .06).
Kayler et al 2020 53 (BHLS/SHLS)	Development and Preliminary Evaluation of An Animation (simplifyKDPI) to Improve Kidney Transplant Candidate Understanding of the Kidney Donor Profile Index	United States/kidney txp candidates(n = 60)	This pre–post study reviewed preliminary evidence of the feasibility and acceptability of the simplified KDPI.	26 participants were deemed to have below median literacy, and 33 participants were deemed to have median literacy or above. In both literacy groups, the animation increased participant knowledge (P < .001).
Kayler et al 2021 54 (BHLS/SHLS variant)	Kidney Transplant Evaluation and Listing: Development and Preliminary Evaluation of Multimedia Education for Patients	United States/kidney txp candidates(n = 28)	This pre–post study aimed to develop and evaluate a novel video education approach to empower patients to proceed with the txp evaluation and listing process and to increase their knowledge and motivation.	9 participants were deemed as having low HL. Large changes in knowledge scores were seen in participants with lower HL (r = 0.48, P = .504).
BMNT
Miller-Matero et al 2015 28 *Also in REALM	Health Literacy in Patients Referred for Transplant: Do Patients Have the Capacity to Understand?	United States/patients being evaluated for liver, kidney, heart or LVAD, lung, or multi-organ txp(n = 398)	Examined the levels of HL and cognitive functioning and characteristics of patients who may have limitations via chart review. Investigated the relationship between reading, math, and cognitive functioning.	27.5% had limited reading ability based on REALM scores. 42.8% had limited math ability (BMNT pre-validation). Males and those who identified as Black were more likely to have limited reading ability (P = .004 and P = .001, respectively). Increased age and those who identified as Black were more likely to have probable cognitive impairment via MoCA (P < .05 and P < .01, respectively).
Miller-Matero et al 2016 10 *Also in REALM	Health Literacy Status Affects Outcomes for Patients Referred for Transplant	United States/patients being evaluated for liver, kidney, heart or LVAD, lung, or multi-organ txp(n = 398)	Retrospective chart review to determine if HL and cognitive impairment were related to being listed for txp and post-txp outcomes	Limited HL (REALM scores) was associated with patients not being listed for txp for nonmedical reasons (P = .044), being removed from the txp list (P = .042), missing appointments before listing (P = .021), and experiencing graft failure/rejection within 6 months after txp (P = .015). Limited numeracy (BMNT scores) was associated with txp listing (P = .015), receiving a txp (P = .031), and being readmitted post-txp (P = .029).
Dykhuis et al 201917, a	A New Measure of Health Numeracy: Brief Medical Numbers Test (BMNT)	United States/patients being evaluated for liver, kidney, heart or LVAD, lung, bone marrow, or multi-organ txp(n = 293)	Evaluated the reliability and validity of the BMNT via retrospective chart review. Evaluated the relationship between BMNT, REALM, REALM-SF, and MoCA results and assess need for additional patient interventions if listed for txp.	BMNT scores were correlated with REALM, REALM-SF, and MoCA scores. Patients with inadequate health numeracy were less likely to be listed for txp (P = .003), were less likely to receive a txp (P = .03), and were more likely to be readmitted within 6 months post-txp (P = .03).
DMCAT
Kazley et al 201418, b	Development and Testing of a Disease-Specific Health Literacy Measure in Kidney Transplant Patients	United States/patients with ESRD or kidney txp(n = 127)	Developed an instrument to evaluate knowledge and decision-making capacity for people with ESRD or on the txp process. Evaluated relationship with DMCAT results and other HL instruments.	Significant differences in HL related to stage of care (clinic access, pre-txp, and post-txp stage). DMCAT scores were correlated with REALM-T and NVS (P < .001).
Kazley et al 2015 32 *Also in NVS and REALM	Health Literacy and Kidney Transplant Outcomes	United States/patients with ESRD (vascular access clinic, pre-txp) or kidney txp(n = 92)	A cross-sectional study evaluated for correlations between HL instruments and the likelihood of being listed for and/or receiving a txp.	DMCAT, NVS, and REALM-T scores predicted whether a patient gets listed for kidney txp (odds ratios 1.408, 1.672, and 1.044; P < .007). NVS and DMCAT predicted whether a patient received a txp (odds ratios 1.667 and 1.256, P < .006).
eHEALS
Gordon et al 2017 55 *Also in NVS	Effect of a Mobile Web App on Kidney Transplant Candidates’ Knowledge About Increased Risk Donor Kidneys: A Randomized Controlled Trial	United States/patients being evaluated for kidney txp(n = 288)	RCT evaluated the efficacy of an iPad app (Inform Me) on kidney txp candidates’ knowledge about increased risk donor kidneys (primary outcome) compared to standard txp education alone. The secondary outcome assessed whether greater knowledge increased willingness to accept IRD kidneys.	53.8% of participants had adequate literacy. Knowledge scores were significantly greater among those with adequate HL and higher eHealth literacy. Adequate HL was independently related to greater knowledge scores, suggesting that kidney txp candidates with inadequate literacy may need assistance comprehending written or statistical information.
Holderried et al 2021 56	Attitude and Potential Benefits of Modern Information and Communication Technology Use and Telemedicine in Cross-Sectoral Solid Organ Transplant Care	Germany/kidney, liver, pancreas, or combined txp recipients(n = 234)	Questionnaire to understand patient use and perceptions of technology in txp care	>75% indicated they knew how to use and evaluate the online information resources for health reasons. 17.6% felt confident in using information from the internet to make health decisions.
Maroney et al 57 2021	eHealth literacy and web-based patient portal usage among kidney and liver transplant recipients	United States/kidney and liver txp recipients(n = 288)	Examined eHealth literacy via phone survey and investigated the association between eHealth literacy and frequency of web-based patient portal utilization	Mean eHEALS = 30.9; higher scores noted among kidney txp patients vs liver txp patients (P = .044); younger txp patients (r = −0.12, P = .039); and patients who received college education (P < .001). Routine portal users had higher eHEALS vs nonusers (OR 1.10, 95% CI 1.03-1.17).
Tang et al 2023 51 *Also SILS	Patients’ Perspectives, Factors, and Patterns of eHealth Use in Kidney Transplant Recipients	Australia/kidney txp recipients(n = 91)	Cross-sectional survey with free responses to determine factors associated with eHealth use, attitudes, and perspectives	Approximately 30% reported adequate eHealth literacy (eHEALS > 32). Mean eHEALS score was 28.10, and SILS score was 1.77. Higher eHEALS scores were associated with higher eHealth use and tertiary education. Among noncurrent eHealth users, most were aware of eHealth and were willing to use eHealth in the future.
HLQ
Demian et al 7 2016	An Observational Study of Health Literacy and Medication Adherence in Adult Kidney Transplant Recipients	Canada/kidney txp recipients(n = 96)	An observational study investigated the effect of lower HL on immunosuppressant adherence.	Kidney recipients reported lower levels on sub-scales measuring health management and critical appraisal of information. Worse adherence (TxEQ-Adherence Subscale) was associated with poorer HL (r2 = 0.08, P = 0.004) and lower scores on 6 of 9 HL domains.
Dahl et al 2020 58	Identifying Core Variables Associated with Health Literacy in Kidney Transplant Recipients	Norway/kidney txp recipients(n = 159)	Cross-sectional study to identify the core variables associated with independent domains of HL 8 weeks following a kidney txp.	The mean scores of the HLQ were above the critical low scores (≤2.0) in domains 1 to 5 and ≤3.0 in domains 6 to 9. General perceived self-efficacy, txp-specific knowledge, and general health were the driving variables in several aspects of HL domains.
Dahl et al 2021 59	Changes in Health Literacy During the First Year Following a Kidney Transplantation: Using the Health Literacy Questionnaire	Norway/kidney txp recipients(n = 196)	Prospective follow-up study to identify changes in HL and associated variables during the first year after a kidney txp. Patients answered the HLQ at 5 days, 8 weeks, 6 months, and 12 months.	Two main patterns were observed: (a) HL increased during the first 8 weeks after the txp and (b) in several domains; the positive increase from 5 days to 8 weeks flattened out from 5 days to 12 months. Self-efficacy, txp-related knowledge, and general health were core variables significantly associated with HL.
Bae et al 2023 60	A Cross-Sectional Analysis of Health Literacy and Compliance to Treatment in Organ Transplant Recipients	South Korea/kidney and liver txp recipients(n = 130)	A cross-sectional study determined the effects of HL on compliance with treatment in organ txp recipients.	The HLQ was translated into a Korean version. “Scale 3: Actively managing my health” (β = 0.38, P = .001) and “Scale 4: Social health support” (β = 0.25, P = .019) had a significant effect on compliance to treatment (measured by K-TxEO).
Vidnes et al 2024 61	Effectiveness of a Health Communication Intervention on Health Literacy in the First Year Following Kidney Transplantation—A Randomized Controlled Study	Norway/kidney txp recipients(n = 195)	RCT evaluated the effect of a new health communication intervention (KnowMAP) focusing on knowledge management skills on health and medication adherence during the first year following kidney txp.	The intervention group had a significant increase in 2 HLQ domains compared to the control group. (HLQ domain 5, “appraisal of health information” [P = .002], and domain 7, “navigating the health-care system” [P < .04]). There was no significant difference in the secondary outcome of graft loss.
NVS
Escobedo and Weismuller 2013 62	Assessing Health Literacy in Renal Failure and Kidney Transplant Patients	United States/patients with visits at a kidney txp center(n = 44)	A descriptive study assessed the level of HL in patients at a suburban txp center.	41% had scores indicating possible likelihood (scores = 2-3) to high likelihood (0-1) of limited HL. Level of education and primary language were significantly related to NVS scores (P = .01 and P = .002).
Kazley et al 2015 32 *Also in DMCAT and REALM	Health Literacy and Kidney Transplant Outcomes	United States/patients with ESRD (vascular access clinic, pre-txp) or kidney txp(n = 92)	A cross-sectional study evaluated for correlations between HL instruments and the likelihood of being listed for and/or receiving a txp.	DMCAT, NVS, and REALM-T scores predicted whether a patient gets listed for kidney txp (odds ratios 1.408, 1.672, and 1.044; P ≤ .007). NVS and DMCAT predicted whether a patient received a txp (odds ratios 1.667 and 1.256, P < 0.006).
Serper et al 2015 9	Medication Misuse, Nonadherence, and Clinical Outcomes Among Liver Transplant Recipients	United States/liver txp recipients(n = 105)	Evaluated medication understanding and adherence to entire medication regimens among liver txp recipients and examined associations with clinical outcomes using structured interviews and EMR data	15% had limited HL. Lower income, less time since txp, higher number of medications, and limited literacy were inversely associated with treatment knowledge scores (P < .05). Limited literacy was associated with nonadherence according to tacrolimus levels (P < .05). After MVA, higher treatment knowledge scores and demonstrated regimen use were associated with 15% and 13% reductions in post-txp rehospitalizations.
Gordon et al 2017 63 *Also in eHEALS	Effect of a Mobile Web App on Kidney Transplant Candidates’ Knowledge About Increased Risk Donor Kidneys: A Randomized Controlled Trial	United States/patients being evaluated for kidney txp(n = 288)	RCT evaluated the efficacy of an iPad app (Inform Me) on kidney txp candidates’ knowledge about increased risk donor kidneys (primary outcome) compared to standard txp education alone. The secondary outcome assessed whether greater knowledge increased willingness to accept IRD kidneys.	53.8% of participants had adequate literacy. Knowledge scores were significantly greater among those with adequate HL and higher eHealth literacy. Adequate HL was independently related to greater knowledge scores, suggesting that kidney txp candidates with inadequate literacy may need assistance comprehending written or statistical information.
Weng et al 2017 41 *Also in BHLS/SLS	A Clustered Randomized Trial of an Educational Intervention During Transplant Evaluation to Increase Knowledge of Living Donor Kidney Transplant	United States/patients being evaluated for kidney txp(n = 499)	Tested the effectiveness of a 1-time educational intervention among patients who presented for evaluation of a kidney txp vs usual-care education to assess efficacy of the educational intervention	Used HL as a variable and descriptor of the patient population. Found that most participants were extremely confident filling out medical forms by themselves (58.6%) and had the highest score category on the NVS (75.2%)
Lennerling et al 2018 37	Health Literacy Among Swedish Lung Transplant Recipients 1 to 5 Years After Transplantation	Sweden/lung txp recipients(n = 117)	A multicenter cross-sectional study investigated HL levels after lung txp in relation to recovery, CF, adherence, fatigue, and demographics.	21% had NVS scores of 0 to 3, indicating low or marginal HL. Patients with higher education levels had higher NVS scores (P ≥ .0001). HL was not related to age, sex, fatigue, adherence, recovery, marital status, or self-reported CF.
Patzer et al 2018 64	Effect of the iChoose Kidney Decision Aid in Improving Knowledge About Treatment Options Among Transplant Candidates: A Randomized Controlled Trial	United States/patients being evaluated for kidney txp(n = 470)	The primary outcome of this RCT was changing patient knowledge about the survival benefits of kidney txp—assessed by using a 9-item scale developed by a multidisciplinary group of txp providers. Secondary outcomes included access to txp, decisional conflict, treatment preferences, and provider opinions on patients’ ability to communicate.	This study focused primarily on txp knowledge compared to HL. However, they did find that patients with lower literacy and numeracy also had lower knowledge scores compared to those with higher literacy and numeracy. All literacy and numeracy subgroups increased knowledge scores with the iChoose Kidney. Those with medium and high literacy and numeracy were able to improve their knowledge more than those with lower literacy and numeracy levels. It did not improve access to kidney txps but did increase the likelihood that clinical providers would discuss the survival benefits of txp vs dialysis and living vs deceased donor txp.
Dore-Stites et al 2020 39 *Also in TOFHLA	Health Literacy and Its Association with Adherence in Pediatric Liver Transplant Recipients and Their Parents	United States/pediatric liver txp recipients and parents(n = 79)	A cross-sectional study examined the HL skills of pediatric liver txp recipients and their parents and correlations with adherence.	100% of parents had adequate HL using TOFHLA, but only 81.7% using NVS. Adolescent patients: 80.6% and 50% had adequate HL with TOHFLA and NVS, respectively. Markers of SES were correlated with HL (patient HL using NVS = age at the time of txp and time since txp [P = .02], education level [P = .000], household income [P = .004], while patient HL using TOFHLA = education of primary caregiver [P = .027] and household income [P = .02]). Parent NVS scores were correlated with the number of biopsy-proven rejection episodes in the year prior (P = .04) and the number of hospitalizations in the year post-study (P = .04), but not any measure of adherence or health outcome. Parent and patient TOFHLA scores were not correlated with adherence or health outcome.
Bittermann et al 2020 35	Low Health Literacy Is Associated With Frailty and Reduced Likelihood of Liver Transplant Listing: A Prospective Cohort Study	United States/patients with ESLD undergoing liver txp evaluation(n = 276)	A prospective cohort study evaluated the relationship between HL and frailty in ESLD and the impact of HL on pre- and post-txp outcomes, accounting for additional factors.	37.7% (104 of 276) had low HL. When education level, SES factors, and severity of illness were adjusted for, low HL was independently associated with physical frailty (aOR 3.59, 95% CI 1.50-8.59; P = .004) and not being waitlisted (aOR 1.96, 95% CI 1.03-3.75; P = .04). Strong social support attenuated the relationship between low HL and not being waitlisted (aOR 1.58, 95% CI 0.74-3.36; P = .24).
Barth et al 2021 65	Experiences of a Patient Education Program Related to Kidney Transplantation in the Eastern Hungary Region	Hungary/patients on the kidney txp waitlist(n = 115)	This follow-up study examined the knowledge level related to renal replacement therapies and kidney transplantation and its influence among chronic kidney disease patients.	63% (n = 159) had adequate HL, and 38% (n = 95) had limited HL. Participants with adequate HL scores achieved significantly higher knowledge scores than those with limited HL (P < .001). Low HL related to a lack of knowledge harms the understanding, evaluation, and application of information related to health and illness. No significant correlation between txp rejection, dialysis treatment, and knowledge scores was determined.
Forsberg et al 2021 66	Fear of Graft Rejection After Heart Transplantation—A Nationwide Cross-Sectional Cohort Study	Sweden/heart txp recipients(n = 79)	A cohort study explored relationships between psychological well-being, fatigue, HL, adherence, and self-efficacy and patients’ perceived risk of graft rejection 1 to 5 years after txp.	28% heart recipients perceived rejection as a serious threat. Recipients with high levels of fatigue and low psychological well-being reported stronger intrusive anxiety and less control. There were no differences in the perceived threat of the risk of graft rejection when comparing three different HL levels (low HL, possibly limited HL, and adequate HL).
Lennerling et al 2021 67	Health Literacy Among Patients with End-Stage Kidney Disease and Kidney Transplant Recipients	Sweden/kidney txp recipients and candidates(n = 99)	A cross-sectional cohort study investigated the levels of HL in kidney txp candidates and recipients.	79 patients achieved a score of 4 to 6, indicating adequate HL. 17 scored 2 to 3 (possibly low HC), and 3 scored 0 to 1 (low HL). There was no significant difference in HL between CKD and kidney txp participants (P = .176).
Maasdam et al 2022 68	Exploring Health Literacy and Self-Management After Kidney Transplantation: A Prospective Cohort Study	The Netherlands/kidney txp recipients(n = 154)	A cohort study measured HL self-management (before discharge and after 6 and 12 months) and investigated the impact on complications.	Higher HL at baseline and at 12 months was related to more viral infections (P = .02; P < .01). The study concluded that HL did NOT influence kidney txp-related outcomes (but higher knowledge and management of symptoms were related to lower graft failure).
Wadhwani et al 202269	Caregiver perspectives on the everyday medical and social needs of long-term pediatric liver transplant patients	United States/parents and caregivers of pediatric liver txp recipients(n = 18)	This qualitative interview-based study describes the everyday medical and social needs of caregivers of long-term survivors of pediatric liver txp with a specific focus on how life circumstances impact txp care and vice versa.	2 (12%) participants had limited or possibly limited literacy, while 16 (88%) had adequate literacy, based on NVS scores. HL was used as a descriptor of the study population.
REALM/REALM-T
Gordon and Wolf 2009 8 *Also in TOFHLA	Health Literacy Skills of Kidney Transplant Recipients	United States/kidney txp recipients(n = 124)	Developed REALM-T and examined the relationship between kidney txp recipients’ HL, txp knowledge, and graft function	8% of patients had marginal or inadequate HL. HL was associated with markers of SES (S-TOFHLA and REALM-T scores and level of education (P ≤ .001) and income (P = .0021). S-TOFHLA and single marital status (P = .046), REALM-T and non-White race (P = .03). After time was controlled for after txp, both REALM-T (P = .03) and S-TOFHLA (P = .04) were negatively correlated with serum creatinine levels.
Kazley et al 2015 32 *Also in DMCAT and NVS	Health Literacy and Kidney Transplant Outcomes	United States/patients with ESRD (vascular access clinic, pre-txp) or kidney txp(n = 92)	A cross-sectional study evaluated for correlations between HL instruments and the likelihood of being listed for and/or receiving a txp	DMCAT, NVS, and REALM-T scores predicted whether a patient gets listed for kidney txp (odds ratios, 1.408, 1.672, and 1.044; P < .007). NVS and DMCAT predicted whether a patient received a txp (odds ratios 1.667 and 1.256, P < .006).
Miller-Matero et al 2015 28 *Also in BMNT	Health Literacy in Patients Referred for Transplant: Do Patients Have the Capacity to Understand?	United States/patients being evaluated for liver, kidney, heart or LVAD, lung, or multi-organ txp(n = 398)	Examined the levels of HL and cognitive functioning and characteristics of patients who may have limitations; investigated the relationship between reading, math, and cognitive functioning	27.5% had limited reading ability based on REALM scores. 42.8% had limited math ability via BMNT (pre-validation). Males and those who identified as Black were more likely to have limited reading ability (P = .004 and P = .001, respectively). Increased age and those who identified as Black were more likely to have probable cognitive impairment via MoCA. (P < .05 and P < .01, respectively).
Miller-Matero et al 2016 10 *Also in BMNT	Health Literacy Status Affects Outcomes for Patients Referred for Transplant	United States/patients being evaluated for liver, kidney, heart, or LVAD, lung, or multi-organ txp(n = 398)	Retrospective chart review to determine if HL and cognitive impairment were related to being listed for txp and post-txp outcomes	Limited HL (REALM scores) were associated with patients not being listed for txp for nonmedical reasons (P = .044), being removed from the txp list (P = .042), missing appointments before listing (P = .021), and experiencing graft failure/rejection within 6 months after transplantation (P = .015). Limited numeracy (BMNT scores) was associated with txp listing (P = .015), receiving a txp (P = .031), and being readmitted post-txp (P = .029).
Patzer et al 2016 36	Medication Understanding, Non-Adherence, and Clinical Outcomes Among Adult Kidney Transplant Recipients	United States/kidney txp recipients(n = 99)	Evaluated the prevalence of medication understanding and nonadherence among kidney txp recipients and the associations with clinical outcomes	24.7% had limited HL based on REALM scores. In MVA, limited HL and fewer months since transplant were associated with medication nonadherence (as measured by self-report or tacrolimus levels) (P < .05).
Bababekov et al 2017 70	Is Liver Transplant Education Patient-Centered?	United States/liver txp candidates and caregivers(n = 100)	Adapted the REALM-T to include liver terms and administered it to liver transplant candidates and caregivers	Caregivers had higher REALM-T scores compared to patients. Both had small statistically significant but clinically insignificant improvements in REALM-T scores after an education session (P < .001).
SAHL-S&E
de Rocha and Figueiredo 2019 71	Letramento em Saúde: Avaliação de pacientes em terapia renal substitutive (Health Literacy: Assessment of Patients Undergoing Renal Replacement Therapy)	Brazil/patients undergoing HD, PD, or kidney txp (n = 138)	Cross-sectional study to assess HL and associations with cognitive aspects, therapeutic adherence, and quality of life	51.4% of patients had inadequate literacy scores (according to the Brazilian version of SAHL). Education and income were associated with inadequate HL (P < .001 and P = .002, respectively).
TOFHLA/S-TOFHLA
Gordon and Wolf 2009 8 *Also in REALM	Health Literacy Skills of Kidney Transplant Recipients	United States/kidney txp recipients (n = 124)	Developed REALM-T and examined the relationship between kidney txp recipients’ HL, txp knowledge, and graft function	8% of patients had marginal or inadequate HL. HL was associated with markers of SES (S-TOFHLA and REALM-T scores and level of education (P ≤ .001) and income (P = .0021). S-TOFHLA and single marital status (P = .046), REALM-T and non-White race (P = .03). After time was controlled for after txp, both REALM-T (P = .03) and S-TOFHLA (P = 0.04) were negatively correlated with serum creatinine levels.
Grubbs et al 2009 72	Health Literacy and Access to Kidney Transplantation	United States/hemodialysis patients(n = 62)	Examined associations between HL and access to the kidney txp waitlist (time for referral for txp evaluation and txp waitlist)	32.3% had inadequate HL. S-TOFHLA scores were lower in those who are >65 (P = .04), have low income (P = .01), and have low education (P < .0005). Participants with inadequate HL had 78% lower hazard of referral for txp evaluation (aHR 0.22; 95% CI 0.08-0.60) (P = .003).
Weng et al 2013 38	Prevalence and Correlates of Medication Non-Adherence Among Kidney Transplant Recipients More Than 6 Months Post-Transplant: A Cross-Sectional Study	United States/kidney txp recipients post 6 months(n = 252)	This cross-sectional study sought to determine the prevalence of self-reported medication nonadherence, psychosocial correlates of nonadherence, and self-reported barriers to medication adherence.	97.6% had adequate HL scores. Only 6 patients had low HL. S-TOFHLA scores were not associated with medication adherence (P = .26).
Robinson et al 2015 73	Response Across the Health-Literacy Spectrum of Kidney Transplant Recipients to a Sun-Protection Education Program Delivered on Tablet Computers: Randomized Controlled Trial	United States/kidney txp recipients(n = 170)	Evaluated the impact of an educational program (SunProtect) on knowledge, intentions to use, and use of sun protection among non-Hispanic White, Hispanic Latino, and non-Hispanic Black kidney txp recipients	28% and 35% of study participants had inadequate and marginal HL, respectively (S-TOFHLA). Hispanic/Latino patients with initial inadequate HL increased knowledge more than non-Hispanic White and Black patients with adequate HL 2 weeks after the educational program (P < .05).
Jones et al 2016 74	Health Literacy, Knowledge, and Patient Satisfaction Before Kidney Transplantation	Canada/patients on kidney txp waitlist(n = 41)	Survey-based study aimed to determine HL (S-TOFHLA) of waitlisted kidney txp patients and to assess kidney txp knowledge, medication beliefs, and patient satisfaction with current education.	91% had adequate HL. Patients with higher HL scores had increased knowledge (r = 0.52, P = .05), understanding of why antirejection medications are necessary (r = 0.38, P = .05), and confidence about taking post-txp medications (r = 0.32, P = .05). Correlations were noted between HL and total knowledge (r = 0.52, P < .05) and between HL and numeracy (r = 0.66, P < .05).
Dore-Stites et al 2020 39 *Also in NVS	Health Literacy and Its Association with Adherence in pediatric Liver Transplant Recipients and Their Parents	United States/pediatric liver txp recipients and parents(n = 79)	A cross-sectional study examined the HL skills of pediatric liver txp recipients and their parents and correlations with adherence.	100% of parents had adequate HL using TOFHLA, but only 81.7% used NVS. Adolescent patients: 80.6% and 50% had adequate HL with TOHFLA and NVS, respectively. Markers of SES were correlated with HL (patient HL using NVS = age at the time of txp and time since txp [P = .02], education level [P = .000], household income [P = .004], while patient HL using TOFHLA = education of primary caregiver [P = .027] and household income [P = .02]). Parent NVS scores were correlated with the number of biopsy-proven rejection episodes in the year prior (P = .04) and the number of hospitalizations in the year post-study (P = .04), but not any measure of adherence or health outcome. Parent and patient TOFHLA scores were not correlated with adherence or health outcome.
Chen et al 2022 33	The Impact of Health Literacy on Kidney Transplant Listing	United States/kidney txp candidates(n = 423)	A retrospective study explored if HL was associated with kidney txp listing after controlling for demographic, psychosocial, and medical variables.	79.2% had adequate TOFHLA scores, with 12.3% and 8.5% having marginal and inadequate scores, respectively. Functional HL scores correlated with txp listing (P = .013), and probability of approval decreased when scores were 0 = 59.

Abbreviations: aOR, adjusted odds ratio; aHR, adjusted hazard ratio; BHLS/SLS, Brief Health Literacy Screen/Short Literacy Survey; BMNT, Brief Medical Numbers Test; BRIGHT, Building Research Initiative Group: Chronic Illness Management and Adherence in Transplantation; CI, confidence interval; CKD, chronic kidney disease; DMCAT, Decision-Making Capacity Assessment Tool; eHEALS, eHealth Literacy Scale; EMR, electronic medical record; ESLD, end-stage liver disease; ESRD, end-stage renal disease; HL, health literacy; HLQ, Health Literacy Questionnaire; HR, hazard ratio; IRD, increased risk donors; K-TxEO, Korean version Transplant Effects Questionnaire; LVAD, left ventricular assist device; MoCA, Montreal Cognitive Assessment; MVA, multivariate analysis; NVS, New Vital Signs; RCT, randomized control study; REALM, Rapid Estimate of Adult Literacy in Medicine; REALM-SF, Rapid Estimate of Adult Literacy in Medicine-Short Form; REALM-T, Rapid Estimate of Adult Literacy in Medicine—Transplantation; SAHL-S&E, Short Assessment of Health Literacy—Spanish and English; SES, socioeconomic status; SHLS, Subjective Health Literacy Screener; SILS, Single-Item Literacy Screener; S-TOFHLA, Short Test of Functional Health Literacy in Adults; TxEQ, Transplant Effects Questionnaire—Adherence Subscale; TOFHLA, Test of Functional Health Literacy in Adults; txp, transplant.

a

Used REALM but did not include under it because the purpose was to validate BMNT.

b

Used REAM and NVS but did not include under it because the purpose was to validate DMCT.

Table 4.

Summary of Tool Usage in Transplantation: Strengths and Limitations.

Short Name	Use in Transplantation	Strengths	Limitations
BHLS/SHLS/SILS/BRIEF/EBHLS	-Used as an outcome measure in 6 studies (Dageforde et al 2014, 40 , Taylor et al 2016, 48 Cajita et al 2017, 49 Taylor et al 2019, 50 Warsame et al 2019, 34 Lorenz et al 2022 11 )-Used as a demographic descriptor/covariate in the analysis of 10 studies (Dageforde et al 2015, 47 Weng et al 2017, 41 Denhaeryck et al 2018, 45 Kaylor 2019/2020/2021,52–54 Tan et al 2020, 42 Tang et al 2023, 51 Mansell et al 2019, 43 Serper et al 2023 44	Quick (1-2 min) depending on the version usedSimple for patients to completeAssessor not requiredLess likely to induce embarrassment or shame in patientsScoring guidelines for adequate HL	Can demonstrate only patients’ self-reported opinionNo assessment of comprehension completedNo set adequate/inadequate HL scores
BMNT	-Used as an outcome measure in 3 studies (Dykhius et al 2019, 17 Miller-Matero et al 2015, 28 Miller-Matero et al 2016 10 )	Quick (2-3 min)Assessor not requiredComprehension and application measured1 incorrect item indicates potential need for support	Assesses numeracy, not literacyMay cause patients to become embarrassed if unable to complete
DMCAT	-Used as an outcome measure in 2 studies (Kazley et al 2014 18 , Kazley et al 2015 32 )	Comprehension and application measuredApplicable to participants health condition	Specific to only the kidney populationsAssessor requiredScoring can be subjective based on the assessorNo set adequate/inadequate HL scores
eHEALS	-Used as an outcome measure in 3 studies (Holderried et al 2021, 56 Maroney et al 2021, 57 Tang et al 2023 51 )-Used as a demographic descriptor/covariate in analysis in 1 study (Gordon et al 2017 55 )	Simple for patients to completeAssessor not requiredUnlikely to induce embarrassment or shame in patients	Can demonstrate only patients’ self-reported opinionNo assessment of comprehension completedNo set adequate/inadequate HL scores
HLQ	-Used as an outcome measure in 5 studies (Demian et al 2016, 7 Dahl et al 2020, 58 Dahl et al 2021, 59 Bae et al 2023, 60 Vidnes et al 2024 61 )-Used in a qualitative study to describe the learning process (Dahl et al 2019 46 )	Assessor not requiredCoverage of 9 HL domainsAvailable in multiple languages	Can demonstrate only patients’ self-reported opinionHigher number of items, risk of patient fatigue20 to 30 min to completeNo set adequate/inadequate HL scoresSubjective scoring of high/low is open to interpretation
NVS	-Used as an outcome measure in 8 studies (Escobedo and Weismuller 2013, 62 Kazley et al 2015, 32 Lennerling et al 2018, 37 Dore-Stites et al 2020, 39 Bittermann et al 2020, 35 Lennerling et al 2021, 67 Forsberg et al 2021, 66 Maasdam et al 2022 68 )-Used as a demographic descriptor/covariate in analysis in 6 studies (Serper et al 2015, 9 Gordon et al 2017, 55 Weng et al 2017, 41 Patzer et al 2018, 64 Barth et al 2021, 65 Wadhwani et al 2022 69 )-Used to validate the DMCAT (Kazley et al 2015 32 )	Quick (3-5 min)Set scoring guidelines for adequate HLComprehension and application measuredAvailable in multiple languagesAssesses literacy and numeracy	Trained assessor requiredAssesses only nutrition labels, not general written textMay cause patients to become embarrassed if unable to completeValidated only in primary care
REALM/REALM-T	-Used as an outcome measure in 5 studies (Gordon and Wolf 2009, 8 Kazley et al 2015, 32 Miller-Matero et al 2015, 28 Miller-Matero et al 2016, 10 Bababekov et al 2017 70 )-Used as a demographic descriptor/covariate in analysis in 1 study (Patzer et al 2016 36 )-Used to validate the BMNT (Dykhius et al 2019 17 )-Used to validate the DMCAT (Kazley et al 2015 32 )	Quick (3-5 min)Set scoring guidelines for adequate HLMultiple versions for different contexts (REALM,22,29 REALM-R, 75 REALM-SF, 76 REALM-Teen, 77 REALM-T 8 )REALM-T terminology specific to kidney transplant populations	Assessor requiredPronunciation of the word does not guarantee understanding or comprehension.May cause patients to become embarrassed if unable to complete
SAHL-S&E	-Used as an outcome measure in 1 study (da Rocha and Figueiredo 2019 71 )	Quick (2-3 min)Scoring guidelines for inadequate HLAvailable in multiple languagesComprehension measured	Assessor requiredMay comprehend words but not be able to apply
TOFHLA/S-TOFHLA	-Used as an outcome measure in 5 studies (Gordon and Wolf 2009, 8 Grubbs et al 2009, 72 Jones et al 2016, 74 Dore-Stites et al 2020, 39 Chen et al 2022 33 )-Used as a descriptor/covariate in 2 studies (Weng et al 2013, 38 Robinson et al 2015 73 )	Assesses comprehension and numeracyMultiple versions (TOFHLA, TOFHLA-S)Scoring guidelines for adequate HLComprehension measuredAvailable in multiple languages7 min to complete (S-TOFHLA)	20 min to complete (TOFHLA)Assessor requiredMay cause patients to become embarrassed if unable to completeTOFHLA is better utilized as a research instrument than a clinical instrument

Abbreviations: BHLS/SLS, Brief Health Literacy Screen/Short Literacy Survey;; BMNT, Brief Medical Numbers Test; DMCAT, Decision-Making Capacity Assessment Tool; EBHLS, Expanded Brief Health Literacy Screen; eHEALS, eHealth Literacy Scale; HL, health literacy; HLQ, Health Literacy Questionnaire; NVS, New Vital Signs; REALM, Rapid Estimate of Adult Literacy in Medicine; REALM-R, Revised Rapid Estimate of Adult Literacy in Medicine; REALM-SF, Rapid Estimate of Adult Literacy in Medicine-Short Form; REALM-T, Rapid Estimate of Adult Literacy in Medicine—Transplantation; REALM-Teen, Rapid Estimate of Adolescent Literacy in Medicine; SAHL-S&E, Short Assessment of Health Literacy—Spanish and English SHLS, Subjective Health Literacy Screener; SILS, Single Item Literacy Screener; TOFHLA, Test of Functional Health Literacy in Adults; TOFHLA-S, Short Test of Functional Health Literacy in Adults.

Table 5.

Domains Assessed by Health Literacy Instruments.

Instrument	Numeracy	Comprehension	Digital HL	Functional HL
BHLS/SHLS/SILS/BRIEF/EBHLS a	✖	✖ (self-report only)	✖	✖ (confidence only)
BMNT	✓	✓ (application)	✖	Partial
DMCAT	✓	✓	✖	✓
eHEALS	✖	✖	✓	✖
HLQ	✖	✓ (self-report)	✖	Partial
NVS	✓	✓	✖	✓
REALM/REALM-T	✖	✖ (word recognition only)	✖	Partial
SAHL-S&E	✖	✓	✖	✓
TOFHLA/S-TOFHLA	✓	✓	✖	✓

Legend:✓ = assesses domain; ✖ = does not assess domain; Partial = limited or indirect assessment.

Abbreviations: BHLS/SLS, Brief Health Literacy Screen/Short Literacy Survey; BMNT, Brief Medical Numbers Test; BRIEF, Brief Health Literacy Screening Tool; DMCAT, Decision-Making Capacity Assessment Tool; eHEALS, eHealth Literacy Scale; EBHLS, Expanded Brief Health Literacy Screen; HL, health literacy; HLQ, Health Literacy Questionnaire; NVS, New Vital Signs; REALM, Rapid Estimate of Adult Literacy in Medicine; REALM-T, Rapid Estimate of Adult Literacy in Medicine—Transplantation; SAHL-S&E, Short Assessment of Health Literacy—Spanish and English; SHLS, Subjective Health Literacy Screener; SILS, Single-Item Literacy Screener; TOFHLA, Test of Functional Health Literacy in Adults; TOFHLA-S, Short Test of Functional Health Literacy in Adults.

a

These tools do not assess health literacy domains directly, but capture subjective, self-reported measures of confidence.

Results

The scoping review was performed following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Protocols (PRISMA-P). ¹³ The PRISMA flowchart in Figure 1 shows the results of the search strategy. Overall, 721 articles were identified for title and abstract assessment, 94 articles were identified and further reviewed for full-text eligibility, and 50 were included in the review.

HL Instruments Identified

Multiple HL assessments have been used in the solid organ transplant population including the BHLS ¹⁴ or SHLS ¹⁵ and alternatives such as the Single-Item Literacy Screener (SILS), ¹⁶ the Brief Medical Numbers Test (BMNT), ¹⁷ the Decision-Making Capacity Assessment Tool (DMCAT), ¹⁸ the eHEALth Literacy Scale (eHEALS), ¹⁹ the HL Questionnaire (HLQ), ²⁰ the Newest Vital Sign (NVS), ²¹ the Rapid Estimate of Adult Literacy in Medicine (REALM), ²² the Rapid Estimate of Adult Health Literacy in Medicine—Transplantation (REALM-T), ⁸ the Short Assessment of Health Literacy (SAHL), ²³ the Test of Functional Health Literacy in Adults (TOFHLA), ²⁴ and the Short Test of Functional Health Literacy in Adults (S-TOFHLA). ²⁵ Most of the HL instruments were developed in the United States (n = 12) with intended use for adult patients (those >18 years of age). Only 1 HL instrument identified was developed in Canada and Australia. Most instruments had been validated in 1 or more studies by testing content and/or construct validity and/or reliability. Of note, only a few instruments were validated specifically within transplant populations, including REALM-T (developed for kidney transplant recipients), DMCAT (validated in end-stage renal disease [ESRD] and kidney transplant candidates), and BMNT (validated in transplant evaluation settings). All other instruments were originally validated in general populations and subsequently applied in transplant research without transplant-specific validation. Table 1 presents the development of the HL instruments, including who, when, and where the instrument was developed; an overview of the target population for which it was developed; and the original validation study.

Instrument Characteristics

A summary of the instrument characteristics is presented in Table 2. HL instruments were categorized as questionnaires or tests. Some instruments (BHLS/SHLS, SILS, eHEALS, and HLQ) used more subjective questionnaires, demonstrating patients’ self-reported opinions or confidence level. Other instruments (BMNT, DMCAT, NVS, REALM, SAHL, and TOFHLA) were characterized as tests (or performance measures), which provided objective assessment based on the number of correct or incorrect answers. Depending on the HL instrument, answers to the questionnaires or tests have been scored and assessed under different thresholds. Typically, a higher score indicates higher HL.

Four of the HL instruments identified can be self-administered. Other instruments, such as the DMCAT, NVS, REALM/REALM-T, SAHL-S&E, and TOFHLA/S-TOFHLA, require an administrator. Many HL instruments (n = 5) can be administered within 1 to 5 min. Conversely, the HLQ and TOFHLA take the longest to administer at 20 to 30 min and 22 min, respectively. The S-TOFHLA is a shortened version of the TOFHLA and can be completed in approximately 7 min.

Other instruments also had multiple versions, and their iterations are outlined in Table 2.

The development of HL screening instruments over time reflects a trend toward creating increasingly concise and targeted methods to identify patients with inadequate HL. Early measures like the BHLS/SLS ¹⁴ focused on general literacy challenges with three questions, while subsequent instruments, such as the SILS ¹⁶ condensed the assessment to a single question for simplicity and ease of use. Instruments like the Brief Health Literacy Screening Tool (BRIEF) ²⁶ and Expanded Brief Health Literacy Screen (EBHLS) ²⁷ continued to expand on earlier work by adding new questions to improve sensitivity and cover broader aspects of HL, such as understanding verbal information and recalling instructions. More specialized instruments, such as the BMNT ¹⁷ and DMCAT, ¹⁸ shifted focus to specific contexts like numeracy during transplantation evaluations and decision-making in chronic illness management. The eHEALS ¹⁹ and HLQ ²⁰ instruments expand beyond basic literacy to assess skills such as using technology and identifying broader HL needs. The NVS ²¹ introduces numeracy as a critical component, using a practical task of interpreting a nutrition label. Similarly, the REALM family ²² focuses on estimating patient literacy levels using reading ability, with adaptations for specific populations, such as the REALM-T, ⁸ which is tailored for transplant recipients. The TOFHLA ²⁴ and its shortened version, the S-TOFHLA, ²⁵ are considered gold-standard assessments, combining both literacy and numeracy within a health-related context. Instruments like the SAHL-S&E ²³ address the needs of bilingual populations by providing validated assessments in both Spanish and English. Additional instruments have also been translated into other languages, as described in Table 2.^14–32 To facilitate quick comparisons for clinicians and researchers, Table 5 summarizes which HL instruments assess key domains such as numeracy, comprehension, digital HL, and functional HL.

HL in Measurement in Solid Organ Transplantation

The most common HL instruments used in transplantation were the BHLS (and iterations) with 16 studies, followed by NVS (15 studies), REALM (8 studies), TOFHLA (7 studies), and HLQ (6 studies). Most articles pertained to kidney transplant (n = 35), followed by liver (n = 4), heart (n = 3), and lung (n = 1) transplants. This imbalance underscores that the evidence base for HL measurement is most mature in kidney transplantation, while research in other organ groups remains limited.^18–32 An additional 7 articles included multiple types of transplants, with 2 articles including hematopoietic/bone marrow transplant. Eighteen studies evaluated HL in pretransplant populations, and 24 studies evaluated posttransplant populations. An additional 8 studies included both pretransplant and posttransplant populations. While most studies exclusively involved patients (n = 47), 1 study also included kidney donors, and 2 studies included caregivers of transplant recipients.

As summarized in Table 3, most studies used HL as an outcome measure, with some investigating factors associated with low HL, such as being waitlisted or evaluated for transplantation, receiving a transplant, adhering to medication, and being rejected. Kazley et al ³² and Chen et al ³³ found that patients with higher HL had an increased likelihood of being listed for transplant compared to those with lower HL. Limited HL was associated with increased risk of waitlist mortality and reduced likelihood of listing. ³⁴ Lorenz et al ¹¹ and Bittermann et al ³⁵ found that patients with lower HL were less likely to be waitlisted. While Demian et al, ⁷ Patzer et al, ³⁶ and Serper et al ⁹ found that lower HL was associated with medication nonadherence, Lennerling et al ³⁷ found no correlation between HL and adherence. Weng et al ³⁸ found no association between S-TOFHLA scores, specifically, and medication adherence, and Dore-Stites et al ³⁹ found no association between adherence and TOFHLA. In other reports, HL was assessed but not used as an outcome measure. Rather, the authors used it to describe their population and/or treat HL as a covariate in the study analysis (eg, Weng et al, ⁴¹ and Tan et al ⁴² ).

The search strategy identified 2 published protocols,^43,44 which were not included in Table 3 as they did not report any results. Two published articles were also excluded from Table 3 as follows. Denhaerynck et al ⁴⁵ used the SHLS instrument, but it was not a significant factor in the study's analysis; Dahl et al used the HLQ to evaluate HL as part of the learning process in 10 qualitative interviews but did not relate HL to any transplantation outcomes. ⁴⁶

Discussion

This review highlights the diversity of HL instruments used in transplant populations and underscores the absence of a universally optimal measure. Each HL instrument has distinct strengths and limitations. Questionnaires such as BHLS, eHEALS, HLQ, SHLS, and SILS rely on patient self-reported understanding or confidence in navigating health information. While easy to administer, self-reporting may overestimate or underestimate a person's actual HL skills. Conversely, assessments such as BMNT, DMCAT, NVS, REALM, SAHL, and TOFHLA are more objective, assessing functional skills like reading, numeracy, or word recognition. However, they may cause embarrassment for patients who struggle with elements of literacy. HL instruments also differ in the specific domains they assess. For example, some instruments focus narrowly on word recognition and pronunciation (e.g., REALM and SAHL), while others evaluate reading ability or print literacy (e.g., TOFHLA). Few instruments assess how one comprehends and utilizes health information in a real-world context. Furthermore, no instrument accounts for broader, important contextual factors such as system-level barriers or individual patient experiences with the healthcare system, which also impact HL.

Several instruments have multiple variations, which can complicate interpretation and comparison. For example, the REALM family includes REALM-SF (a 7-item short form for quick screening), REALM-R (with more complex words), and the REALM-T (tailored to transplant terminology). Both the REALM and REALM-T were identified in transplant literature (n = 6). Similarly, TOFHLA and its shortened version, S-TOFHLA, were commonly used. TOFHLA provides a comprehensive assessment of reading comprehension and numeracy using real healthcare materials, whereas S-TOFHLA offers a quicker alternative focused on reading comprehension. Short Likert-scale questionnaires such as SLS, BHLS/SHLS, BRIEF, SILS, and EBHLS share similar core questions, with BRIEF and EBHLS adding extra items. SLS and BHLS/SHLS are essentially the same instruments under different names. This overlap adds complexity when categorizing and comparing HL instruments.

Since no comprehensive measure exists, certain instruments may be more suitable in specific settings. For example, when HL is assessed as a primary outcome in research, instruments with detailed scoring systems (eg, TOFHLA) or those that offer assessment of multiple domains (eg, HLQ) may offer a more nuanced understanding. Where HL is assessed as a covariate, simpler instruments (eg, BHLS family) may be sufficient. In clinical settings, quicker instruments may be more practical. Instruments such as the BRIEF family or NVS take 1 to 5 min to complete and may be more practical compared to the TOFHLA or HLQ, which require 20 to 30 min. Furthermore, some instruments (eg, DMCAT, NVS, REALM, SAHL, and TOFHLA) require trained personnel for administration, which can complicate workflow. Of note, many of these instruments were validated or used in outpatient clinical settings. Application of these instruments in other settings may affect validity and results.

In the transplant setting, subjective tools (eg, BHLS, SILS, and HLQ) are well-suited for initial screening during routine clinic visits because they are brief, self-administered, and impose minimal burden on patients and staff. In contrast, objective tools (eg, TOFHLA, NVS, and REALM) provide a more comprehensive assessment of functional literacy and numeracy and may be preferable during pretransplant evaluations, where understanding complex instructions and medication regimens is critical for eligibility and long-term success. For long-term follow-up, subjective tools may again be practical for monitoring changes in perceived confidence and identifying emerging challenges, while objective tools could be reserved for cases where adherence issues or complications suggest a need for deeper assessment. Ultimately, combining both approaches in high-risk patients may offer the most robust strategy for tailoring interventions. Among the transplant studies we identified, associations between HL and outcomes such as adherence were inconsistent. Some studies linked low HL to nonadherence, while others found no correlation. These discrepancies likely stem from methodological differences, population heterogeneity and instrument focus, underscoring potential limitations with HL measurement and the need for standardized measurement approaches in transplant research.

HL is deeply intertwined with cultural, linguistic, and socioeconomic factors, yet most instruments identified were developed and validated in English-speaking populations, primarily in the United States. While some tools, such as SAHL-S&E, provide validated versions in Spanish and English, few offer multilingual adaptations or account for cultural nuances. Similarly, most tools assume a baseline level of formal education and cognitive function, which may limit applicability for patients with low literacy, limited schooling, or cognitive impairment. These validation gaps can result in misclassification of HL in minority populations, leading to inequitable support, poorly tailored health interventions, and the reinforcement of existing health disparities. These gaps highlight the need for instruments that are culturally sensitive, linguistically adaptable, and inclusive of diverse patient populations to ensure equitable assessment and care.

This systematic review has several limitations. First, the search strategy specifically included the term “health literacy,” which means studies that failed to explicitly mention HL in the title or abstract may have been missed. Additionally, the review focused on instruments that directly measure HL; instruments that primarily evaluate health-related knowledge or disease-specific understanding were excluded. While the original validation studies for each HL instrument were analyzed, secondary validation studies that may have assessed the instruments in additional populations or settings were not included. Furthermore, several studies used the instruments primarily as descriptive covariates rather than as main outcomes, which may reduce interpretive depth regarding their impact on clinical endpoints. Generalizability may be limited since the review relies heavily on instruments developed in the United States, and cultural and linguistic differences can impact HL. Furthermore, all studies were in English. The studies also differed in quality and sample sizes, and many were focused on kidney transplant populations.

Identified instruments assess individual HL, whereas organizational HL, as emphasized by Healthy People 2030, ² is increasingly recognized as critical for equitable care. This distinction is important because organizational factors can significantly impact patient comprehension and engagement. Finally, although scoping reviews do not typically assess publication bias formally, it is possible that studies reporting significant associations between HL and outcomes were more likely to be published, introducing potential bias that should be acknowledged.

Conclusion

As HL becomes an increasingly important focus in health-based research, the number of instruments for measuring HL continues to grow. However, no single instrument offers a comprehensive measure of HL. This review highlights the HL instruments used in transplant populations, outlines their strengths and limitations, and guides healthcare providers and researchers seeking to integrate HL assessment into clinical practice or research. To enhance practical utility, we suggest recommendations for selecting instruments based on context:

For rapid clinical screening or research contexts where HL is a covariate, brief tools such as the BHLS, SILS, and NVS are ideal for quick administration.

For research-focused assessments, where HL is the primary outcome, comprehensive instruments like the TOFHLA, S-TOFHLA, and HLQ provide detailed insights into multiple domains.

In digital health contexts, the eHEALS was specifically designed to assess patients’ ability to navigate and use digital health resources.

In caregiver-centered or broader contexts, instruments such as the HLQ allow for multidimensional assessment and can be adapted for caregiver involvement or proxy reporting.

By integrating HL assessment into transplant care and research, healthcare teams can better identify patients at risk, tailor communication strategies, and ultimately improve outcomes across the transplant trajectory.

Supplemental Material

sj-docx-1-pit-10.1177_15269248261432238 - Supplemental material for A Scoping Review and Practical Approach to Measuring Health Literacy in Solid Organ Transplantation

Supplemental material, sj-docx-1-pit-10.1177_15269248261432238 for A Scoping Review and Practical Approach to Measuring Health Literacy in Solid Organ Transplantation by Vanessa Phommavong, Breanna Morrison, Nicola Rosaasen, Kathryn Haubrich, Irène Pandraud-Riguet and Holly Mansell in Progress in Transplantation