Validating the Use of TBI-CareQOL Measures in Caregivers of People Living With Dementia

Abstract

Understanding the clinical utility of patient-reported outcome measures is critical for using these measures in research and clinical practice. Therefore, the purpose of this analysis was to establish the psychometric properties of three TBI-CareQOL measures in caregivers of people living with Alzheimer’s disease or Alzheimer’s disease-related dementias (ADRD): Caregiver Strain, Caregiver-Specific Anxiety, and Feeling Trapped. One-hundred-and-ninety-seven caregivers of individuals living with ADRD (n=197) completed three TBI-CareQOL measures, three additional measures to establish convergent and discriminant validity (NIH Toolbox Perceived Stress, Dementia Management Strategies Scale, PROMIS Pain Intensity), and the Dementia Severity Rating Scale to establish known groups validity. Internal consistency and test-retest reliability of the TBI-CareQOL measures were supported (alphas >.70). The TBI-CareQOL measures were also free of floor and ceiling effects. Convergent, discriminant, and known groups validity were also supported. Taken together, findings support the clinical utility of the TBI-CareQOL measures for caregivers of people living with ADRD.

Keywords

HRQOL informal caregivers caregiver burden patient-reported outcome psychometrics Alzheimer’s disease

Understanding the clinical utility of patient-reported outcome measures (PROs) is critical for using them with confidence in research and clinical practice. Unfortunately, many researchers use PROs in new clinical populations without having information about score reliability and validity in a given population, which can be problematic for interpretation of findings.¹ For example, when findings do not align with a proposed hypothesis, it is unclear whether there are no significant effects, or if the measure itself performs differently in this new population (i.e., the psychometric properties are invalid for this new population). To this end, establishing the psychometric reliability and validity prior to using a new measure in a clinical population is important.

Recently, the TBI-CareQOL measurement system was developed to capture the impact that the caregiver role has on health-related quality of life (HRQOL).^2,3 Creating TBI-CareQOL involved the development of several new PROs that are specific to caregivers, as well as validating existing measures of general HRQOL concepts in the caregiver population. The new caregiver measures were initially developed for use in caregivers of people with traumatic brain injury, but have since been validated in several other caregiver populations including caregivers of people with cancer, caregivers of people with Huntington disease, and caregivers of people with spinal cord injury.⁴ Unfortunately, none of this validation work has focused on one of the most well-studied and common caregiver populations, caregivers of people with Alzheimer’s disease or Alzheimer’s disease-related dementias (ADRD).

It is estimated that over 16 million family members and friends provide care to persons living with AD/ADRD, with estimated hours of care exceeding 18.5 billion, annually.⁵ Decades of research suggest that caregiver strain (aka caregiver burden) has a profound negative effect on both the care partner as well as the person living with ADRD. Specifically, strain associated with the caregiver role is both common and linked with decreased well-being, depressed mood, increased anxiety, anger, guilt, and vulnerability to disease for the care partner,^6-8 as well as decreased well-being, depressed mood, poor treatment adherence, and increased health services utilization in the person living with ADRD.^9-15 Most informal care partners have had little training and do not have time to adequately prepare themselves for their caregiving role.^5,16 Thus, there is a critical need to better understand and support individuals that assume this important role.

Prior research on caregivers commonly assesses a single domain of HRQOL, specifically caregiver burden or stress. For example, both the Zarit Burden Interview¹⁷ and the Perceived Stress Scale¹⁸ have been used in caregivers of dementia, as well as more broadly, but these measures are limited by the fact that they focus on only a single domain of HRQOL, namely stress/burden. While such tools are valuable for understanding caregiver outcomes, they do not provide a comprehensive assessment of HRQOL. Thus, there is a pressing need for a measurement system that can capture a holistic view of issues specific to the HRQOL of caregivers for individuals living with ADRD.

In contrast, the TBI-CareQOL measures capture multiple domains of functioning and were developed using both classical test theory and item-response theory (IRT). This development approach offers advantages including: 1) each individual item on the measure can be used to estimate a score (i.e., missing data does not impact the ability to generate a score¹⁹); 2) data from item response theory can be used to program a computer adaptive test administration (where only the most informative items for each participant are administered^20,21), which has the advantages of brevity without the loss of precision²²; and 3) this approach permits standardized scoring, i.e., a T metric (M=50, SD=10), that allows for easy interpretation. Given these advantages, as well as the more comprehensive nature of the TBI-CareQOL measurement system, we aimed to establish the psychometric properties of the Caregiver Strain, Caregiver-Specific Anxiety, and Feeling Trapped CareQOL measures in a sample of caregivers of people with ADRD. Specifically, we examined internal consistency reliability, test-retest reliability, as well as convergent, discriminant and known groups validity in this population. We also report the effect sizes for scores to help inform the utility of these measures in clinical research.

Methods

Participants

This secondary data analysis included 197 caregivers of people living with ADRD. Caregivers had to be at least 18 years of age and providing unpaid physical, emotional, or financial assistance to someone with dementia. Caregivers and/or care-recipients could not be bedbound, living in a long-term care facility, nor have a life expectancy of 6 months or less. Recruitment sources included medical record databases, caregiver or dementia research registries, social media, and community events. A detailed description of the broader study is provided elsewhere.²³

Measures

Survey measures were part of a larger assessment battery that is described elsewhere.²³ The measures that were considered in this paper are described below.

CareQOL Caregiver-Specific Measures

Three different TBI-CareQOL measures were administered including: 1) the TBI-CareQOL Caregiver Strain short form (SF^3,24), which assesses caregiver burden; 2) the TBI-CareQOL Caregiver-Specific Anxiety SF,^3,25 which assesses anxiety that is specific to the caregiver role; and 3) the TBI-CareQOL Feeling Trapped SF,^3,26 which assesses feelings of being unable to leave the care-recipient alone or with another caregiver. All measures were adapted such that reference to “person with the injury” was modified to read “person with the illness.” Scores on these measures were converted to a T metric (M = 50; SD = 10) such that higher scores indicate worse caregiver-specific HRQOL.

Convergent and Discriminant Validity Measures

The NIH Toolbox Perceived Stress SF²⁷ is a 10-item short form designed to capture feelings of being stressed or overwhelmed. Scores on this measure are on a T metric (M = 50; SD = 10) such that higher scores indicate worse stress. This measure was used to examine the convergent validity of Caregiver Strain and Caregiver-Specific Anxiety. In addition, CG-Specific Anxiety (described above) was used to examine the convergent validity of Feeling Trapped. The Dementia Management Strategies Scale²⁸ is a 28-item scale that is designed to capture how frequently caregivers have engaged in different management strategies during the past month. This scale includes three subscale scores on criticism, active management and encouragement. We used scores on active management and encouragement to establish discriminant validity of the CareQOL measures. The PROMIS Pain Intensity SF was used to assess self-reported perceptions of pain. Scores are on a T metric (M=50; SD=10), with higher scores indicating more pain intensity. This measure was also used to establish the discriminant validity of the CareQOL measures in caregivers of people with ADRD.

Known Groups Validity Measures

Known groups validity was established by comparing CareQOL measures by symptom severity of the care recipient. The Dementia Severity Rating Scale (DSRS²⁹) is a 12-item proxy report measure of dementia severity. Scores range from 0-54; scores of 0-18 are considered mild, 19-36 indicate moderate, and 37-54 indicate severe dementia.

Statistical Analysis

SAS v9.4 was used to analyze the data.

Internal Consistency and Measurement Characteristics

Cronbach’s alpha was used to examine internal consistency reliability (criterion≥ 0.70^30,31). Floor and ceiling rates were examined by calculating the number of people with the highest (responding “always” to all SF items) and lowest (responding “never” to all SF items) possible scores for each measure (criterion ≤20%^32,33).

Convergent and Discriminant Validity

We examined Pearson correlations between the CareQOL measures and the specified comparators. We expected moderate (0.36 ≤ r ≤ 0.67) to strong (0.68 ≤ r ≤ 0.89) correlations between the CareQOL measures and Perceived Stress,³⁴ and weak correlations (r’s ≤ 0.35) between the CareQOL measures and Pain Intensity, Active Management and Encouragement measures.³⁴

Known Groups Validity

T-tests were used to compare CareQOL scores between caregivers caring for someone that is low versus high functioning (i.e., those with DSRS scores of 0-18 versus 19-54). We expected those caring for someone with more severe dementia to indicate worse caregiver-specific HRQOL than those caring for someone with less severe dementia.

Results

A total of 197 caregivers of people living with dementia participated in this study. Descriptive data for the sample is provided in Table 1. CareQOL internal consistency, reliability, and test-retest reliability were supported and ranged from very good to excellent (αs ≥ .84; Table 2). The measures were also devoid of both floor and ceiling effects (Table 2).

Table 1.

Sample Characteristics (n=197)

Variable	n (%)/M (SD)
Sex
Female	165 (84)
Male	32 (16)
Not reported
Race
Native American or Alaska Native	4 (2)
Native Hawaiian or other Pacific Islander	1 (1)
Asian	9 (5)
Black or African American	29 (15)
White or Caucasian	150 (76)
Other	3 (2)
Do not wish to report	1 (1)
Ethnicity (%)
Non-Hispanic	185 (94)
Hispanic	9 (5)
Do not wish to report	3 (2)
Marital Status (%)
Married or Cohabitating	131 (66)
Separated	3 (2)
Single & divorced	21 (11)
Single & never married	34 (17)
Single & widowed	8 (4)
Work Status (%)
Full-time (at least 35 hours per week)	61 (31)
Part-time (<35 hours per week)	40 (20)
Homemaker	11 (6)
Student	1 (1)
Retired	73 (37)
Disabled	3 (2)
Unemployed	7 (4)
Other	1 (1)
Age (years)	59.1 (14.3)
Time in caregiver role (years)
Less than 1 year	16 (8)
1-2 years	41 (21)
3-4 years	68 (35)
5-6 years	27 (14)
7 or more years	44 (22)
Do not wish to report	1 (1)
Relationship to patient (%)
Partner/Spouse	69 (35)
Child	83 (42)
Sibling	5 (3)
Other family	21 (11)
In-law	11 (6)
Friend	8 (4)
Missing	0
Time caregiving (%)
1-2 hrs/day or less	39 (20)
3-4 hrs/day (half a working day)	53 (27)
5-8 hrs/day (full working day)	39 (20)
9-12 hrs/day	22 (11)
>12 hrs/day or round-the-clock care	44 (22)
Age of care-recipient (years)	78.8 (9.5)
Sex of care-recipient
Female	112 (57)
Male	85 (43)

^*There were no other significant differences among these four groups for these demographic variables.

Table 2.

Descriptive Information and Reliability Data for CareQOL Measures

TBI-CareQOL measure	M (SD)	Internal consistency	Test-retestreliability	Floor %	Ceiling %
Caregiver Strain	53.9 (7.7)	0.90	0.84	1.6	1.6
Caregiver-Specific Anxiety	51.9 (7.3)	0.87	0.85	0.5	2.6
Feeling Trapped	55.4 (7.0)	0.89	0.84	1.6	3.1

Note. TBI-CareQOL: Traumatic Brain Injury Caregiver Quality of Life.

A priori hypotheses for convergent validity and discriminant validity were supported (Table 3). With regard to convergent validity, Pearson correlations between each of the CareQOL measures and their closest comparator measures were moderate to high. With regard to discriminant validity, Pearson correlations between each CareQOL measure and each of the comparators were all low (r’s ≤0.26). In addition, all a priori hypotheses for known groups validity were supported for each of the CareQOL measures with the exception of the difference between high- and low-confidence caregivers on Feeling Trapped, which approached significance (Table 4).

Table 3.

Convergent and Discriminant Validity

TBI-CareQOL measure	Convergent validity	Discriminant validity
TBI-CareQOL measure	Convergent validity	Pain intensity	DMS active management	DMS encouragement
Caregiver Strain	Perceived Stress	0.26	−0.15	−0.25
Caregiver Strain	0.76*	0.26	−0.15	−0.25
Caregiver-Specific Anxiety	Perceived Stress	0.23	−0.05	0.26
Caregiver-Specific Anxiety	0.68*	0.23	−0.05	0.26
Feeling Trapped	CG-Specific Anxiety	0.10	−0.15	−0.19
Feeling Trapped	0.46*	0.10	−0.15	−0.19

Note. TBI-CareQOL: Traumatic Brain Injury Caregiver Quality of Life; DMS: Dementia Management Strategy; CG-specific: Caregiver-specific.

*p<.05.

Table 4.

Known Groups Validity

Care recipient functioning
	Less severe dementia (n = 60)		More severe dementia (n = 127)		t	p	d
	Mean (SD)	% Impaired (>60)	Mean (SD)	% Impaired (>60)	t	p	d
Caregiver Strain	51.4 (7.9)	13	54.8 (7.5)	22	2.82	.005	0.43
Caregiver-Specific Anxiety	49.5 (7.2)	7	52.8 (7.2)	12	2.88	.005	0.44
Feeling Trapped	51.9 (6.1)	8	57.0 (6.9)	35	4.86	<.001	0.72

Note. CAT: computer adaptive test; SF: short form.

Discussion

Caregiver strain experienced by caregivers for individuals living with ADRD has been shown to be associated with numerous negative consequences for both the caregiver and care recipient. Thus, having psychometrically valid tools to assess HRQOL in this population is critical to identifying needs and providing support for this underserved population. While the TBI-CareQOL measurement system was developed specifically for use in caregivers of individuals with TBI, prior research suggests that these measures may also be valid for other caregiver cohorts.

In an independent sample of caregivers of individuals living with ADRD, we showed that CareQOL measures of Caregiver Strain, Caregiver-Specific Anxiety, and Feeling Trapped were both reliable and valid for this population. We found evidence for internal consistency and test-retest reliability for each of the three measures, and these values were in line with what has been found in other caregiver populations.^4,35 Specifically, in our sample of ADRD caregivers: 1) internal consistency for Caregiver Strain was excellent (0.90) compared to internal consistency values that ranged from very good to excellent in other caregiver populations (0.84 to 0.92); 2) internal consistency for Caregiver-Specific Anxiety was very good (0.87) compared to other caregiver populations which ranged from acceptable to excellent (0.78 – 0.93); and 3) internal consistency of Feeling Trapped was very good (0.89) relative to caregivers of individuals with TBI which was excellent (0.92^4,35). Furthermore, test reliability in this sample of ADRD caregivers was very good (0.84 for Caregiver Strain and Feeling Trapped and 0.85 for Caregiver-Specific Anxiety), compared to the excellent test-retest reliability reported in caregivers of individuals with TBI (0.93 for Caregiver Strain and Caregiver-Specific Anxiety and 0.94 for Feeling Trapped³⁵).

We also found evidence for convergent validity with Perceived Stress, and discriminant validity with measures of Pain Intensity, Active Management, and Encouragement. Known groups validity was established by demonstrating that caregiver HRQOL was significantly worse for caregivers caring for individuals who are low functioning (high symptom severity). These findings are aligned with the other reported findings in caregivers of people with traumatic brain injury, cancer, Huntington disease, and spinal cord injury.^4,35

All three CareQOL measures were free of ceiling and floor effects. Floor and ceiling effects were also comparable, or lower than what has been reported in other caregiver populations: 1) the ceiling effect for Caregiver Strain was 1.6% in this sample relative to other samples which range from 0 to 5%, and the floor effect in this sample was 1.6% relative to 1 to 2% in other caregiver samples; 2) the ceiling effect for Caregiver-Specific Anxiety was 0.5% in this sample relative to other samples which range from 0 to 7%, and the floor effect in this sample was 2.6% relative to 0% in other caregiver samples; and 3) the ceiling effect for Feeling Trapped was 1.6% in this sample relative to 14% for caregivers of individuals with TBI, and the floor effect in this sample was 3.1% relative to 0% caregivers of individuals with TBI.^4,35

While legacy measures exist that capture caregiver-specific outcomes, including caregiver strain, emotional distress, and role captivity, they typically fail to isolate the care-related dimensions of anxiety and treat feelings of entrapment as secondary or subordinate constructs.³⁶ Likewise, more recent caregiver-specific (e.g., the Zarit Burden Inventory³⁷) are not cross-cutting nor do they provide scores across multiple caregiving domains, whereas more recent generic measures, such as those from the Patient-Reported Outcome Measurement Information System (PROMIS)^20,21 do not capture caregiver-specific constructs.³⁸ The CareQOL measurement system directly addresses these gaps by providing caregiver-specific instruments tailored to the lived realities of caregiving. Through robust validation across multiple chronic conditions—including ADRD—we demonstrate that the TBI-CareQOL fills the need for unified, care-context sensitive outcomes assessment, aligning with current research imperatives and enhancing the clinical utility of caregiver evaluations.

More sepcifically, the findings from this study also have several practical implications for research and practice in ADRD care. Reliable and valid measures of constructs such as Caregiver Strain, Caregiver-Specific Anxiety, and Feeling Trapped can be used by clinicians and care teams to systematically identify caregivers at risk for adverse outcomes, enabling early intervention and targeted support. For example, integrating these measures into routine caregiver assessments could inform the development of screening tools to detect unmet needs and to monitor changes in caregiver well-being over time. Such information is critical for tailoring interventions—including psychoeducation, respite, or mental health services—ultimately improving outcomes for both caregivers and individuals living with ADRD.

This work also extends the established literature by showing that tools developed for caregivers in the TBI context possess cross-diagnostic relevance for ADRD caregivers, reinforcing the concept that the core aspects of caregiver burden and well-being are shared across neurological and chronic illnesses. Compared to prior studies in TBI, Huntington disease, and cancer, and spinal cord injury,^4,35 our findings suggest that a common HRQOL framework may facilitate benchmarking and improve continuity in caregiver support programs. Future validation studies should further explore the responsiveness of these measures to intervention and their predictive utility for clinical decision-making, as well as assess their applicability across diverse demographic and care settings.

While this investigation provides promising evidence for the use of CareQOL measures with caregivers of individuals living with ADRD, it is important to note that these data are not sufficient by themselves to warrant clinical use of CareQOL measures with this population. Measurement validation for a population requires the accumulation of evidence from multiple studies of different samples. We hope that these data are the beginning of the development of a large body of evidence to support the clinical use of CareQOL measures with caregivers for individuals living with ADRD. These measurement tools will allow researchers and clinicians to capture a holistic view of caregiver QOL by assessing caregiver-specific issues and needs. Additionally, one limitation of the presented research is that the results rely on secondary data that were not collected to specifically establish the psychometric properties of CareQOL measures for caregivers of individuals living with ADRD.

Conclusion

In conclusion, this study provides new evidence supporting the clinical utility of the TBI-CareQOL measures in capturing salient aspects of HRQOL among caregivers of people living with ADRD providing a step towards potenrial data elements that can be used across different caregiving populations. Building on these results, future research should aim to validate additional CareQOL domains (e.g., Feelings of Loss, Emotional Suppression, Caregiver Vigilance) and investigate practical strategies for implementing these tools into routine clinical workflows. Moreover, larger and more diverse samples will be needed to confirm generalizability and to clarify optimal cutoff scores for identifying those at highest risk. By advancing measurement science in this area, these efforts could drive improvements in caregiver support, resource allocation, and ultimately, the quality of ADRD care.

Footnotes

ORCID iDs

Noelle E. Carlozzi

Madison Fansher

Jonathan P. Troost

Jennifer A. Miner

Sophia Tsuker

Amanda N. Leggett

Ethical Considerations

This study was approved by the Michigan Medicine IRB.

Consent to Participate

Informed consent was provided by all participants.

Author Contributions

NEC: Conceptualization, Methodology, Writing – Original Draft, Writing -Review and Editing, Supervision, Funding Acquisition. MF: Writing – Original Draft, Writing -Review and Editing. JPT: Methodology, Data Curation, Formal Analysis, Writing – Original Draft, Writing -Review and Editing. JAM: Conceptualization, Methodology, Data Curation, Writing -Review and Editing, Supervision, Project Administration, Funding Acquisition. ST: Data Collection, Data Curation, Writing -Review and Editing. ANL: Conceptualization, Methodology, Writing – Original Draft, Writing -Review and Editing, Supervision, Project Administration, Funding Acquisition.

Funding

The authors disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was funded by an Alzheimer’s Association & LINC-AD “Advancing Research on Care and Outcome Measurement (ARCOM) Program” award (ARCOM-22-876659; PI: Leggett) which was partially supported by the Dementia Care Provider Roundtable. Dr. Leggett is also funded by NIAP30AB072931. National Institute of Nursing Research (R01NR013658).

Declaration of Conflicting Interests

The authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Data Availability Statement

The data supporting the findings of this study are available upon reasonable request from the corresponding author.*

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