The Impact of Numeracy on Verbatim Knowledge of the Longitudinal Risk for Prostate Cancer Recurrence following Radiation Therapy

Abstract

Objective. Given the long natural history of prostate cancer, we assessed differing graphical formats for imparting knowledge about the longitudinal risks of prostate cancer recurrence with or without ‘hormone’ or ‘androgen deprivation’ therapy. Methods. Male volunteers without a history of prostate cancer were randomized to 1 of 8 risk communication instruments that depicted the likelihood of prostate cancer returning or spreading over 1, 2, and 3 years. The tools differed in format (line, pie, bar, or pictograph) and whether the graph also included no numbers, 1 number (indicating the number of affected individuals), or 2 numbers (indicting both the number affected and the number unaffected). The main outcome variables evaluated were graphical preference and knowledge. Results. A total of 420 men were recruited; respondents were least familiar and experienced with pictographs (P < 0.0001), and only 10% preferred this particular format. Overall accuracy ranged from 79% to 92%, and when assessed across all graphical subtypes, the addition of numerical information did not improve verbatim knowledge (P = 0.1). Self-reported numeracy was a strong predictor of accuracy of responses (odds ratio [OR] = 2.6, P = 0.008), and the impact of high numeracy varied across graphical type, having a greater impact on line (OR = 5.1; 95% confidence interval [CI] = 1.6–16; P = 0.04) and pie charts (OR = 7.1; 95% CI = 2.6–19; P =0.01), without an impact on pictographs (OR = 0.4; 95% CI = 0.1–1.7; P = 0.17) or bar charts (OR = 0.5; 95% CI = 0.1–1.8; P = 0.24). Conclusion. For longitudinal presentation of risk, baseline numeracy was strongly prognostic for outcome. However, the addition of numbers to risk graphs improved only the delivery of verbatim knowledge for subjects with lower numeracy. Although subjects reported the least familiarity with pictographs, they were one of the most effective means of transferring information regardless of numeracy.

Keywords

decision aids patient decision making risk communication risk perception

Get full access to this article

View all access options for this article.

References

Souhami

Bae

Pilepich

Sandler

. Timing of salvage hormonal therapy in prostate cancer patients with unfavorable prognosis treated with radiotherapy: a secondary analysis of Radiation Therapy Oncology Group 85-31. Int J Radiat Oncol Biol Phys. 2010;78(5):1301–6.

Saylor

Keating

Smith

. Prostate cancer survivorship: prevention and treatment of the adverse effects of androgen deprivation therapy. J Gen Intern Med. 2009;24(Suppl 2):S389–94.

Taylor

Sandler

. Individualized predictions of disease progression following radiation therapy for prostate cancer. J Clin Oncol. 2005;23(4):816–25.

Feldman-Stewart

Brundage

Zotov

. Further insight into the perception of quantitative information: judgments of gist in treatment decisions. Med Decis Making. 2007;27(1):34–43.

Hawley

Zikmund-Fisher

Ubel

Jancovic

Lucas

Fagerlin

. The impact of the format of graphical presentation on health-related knowledge and treatment choices. Patient Educ Couns. 2008;73(3):448–55.

Lipkus

Samsa

Rimer

. General performance on a numeracy scale among highly educated samples. Med Decis Making. 2001;21(1):37–44.

Peters

Hibbard

Slovic

Dieckmann

. Numeracy skill and the communication, comprehension, and use of risk-benefit information. Health Aff (Millwood). 2007;26(3):741–8.

Dale

Hemmerich

Bylow

Mohile

Mullaney

Stadler

. Patient anxiety about prostate cancer independently predicts early initiation of androgen deprivation therapy for biochemical cancer recurrence in older men: a prospective cohort study. J Clin Oncol. 2009;27(10):1557–63.

Fagerlin

Ubel

Smith

Zikmund-Fisher

. Making numbers matter: present and future research in risk communication. Am J Health Behav. 2007;31(Suppl 1):S47–56.

10.

Fagerlin

Rovner

Stableford

. Patient education materials about the treatment of early-stage prostate cancer: a critical review. Ann Intern Med. 2004;140(9):721–8.

11.

Elwyn

O’Connor

Stacey

. Developing a quality criteria framework for patient decision aids: online international Delphi consensus process. BMJ. 2006;333(7565):417.

12.

Edwards

Thomas

Williams

Ellner

Brown

Elwyn

. Presenting risk information to people with diabetes: evaluating effects and preferences for different formats by a web-based randomised controlled trial. Patient Educ Couns. 2006;63(3):336–49.

13.

Schapira

Nattinger

McAuliffe

. The influence of graphic format on breast cancer risk communication. J Health Commun. 2006;11(6):569–82.

14.

Timmermans

Ockhuysen-Vermey

Henneman

. Presenting health risk information in different formats: the effect on participants’ cognitive and emotional evaluation and decisions. Patient Educ Couns. 2008;73(3):443–7.

15.

Price

Cameron

Butow

. Communicating risk information: the influence of graphical display format on quantitative information perception: accuracy, comprehension and preferences. Patient Educ Couns. 2007;69(1–3):121–8.

16.

Burkell

. What are the chances? Evaluating risk and benefit information in consumer health materials. J Med Libr Assoc. 2004;92(2):200–8.

17.

Fagerlin

Wang

Ubel

. Reducing the influence of anecdotal reasoning on people’s health care decisions: is a picture worth a thousand statistics? Med Decis Making. 2005;25(4):398–405.

18.

Tait

Voepel-Lewis

Zikmund-Fisher

Fagerlin

. The effect of format on parents’ understanding of the risks and benefits of clinical research: a comparison between text, tables, and graphics. J Health Commun. 2010;15(5):487–501.

19.

Brundage

Feldman-Stewart

Leis

. Communicating quality of life information to cancer patients: a study of six presentation formats. J Clin Oncol. 2005;23(28):6949–56.

20.

Zikmund-Fisher

Fagerlin

Ubel

. What’s time got to do with it? Inattention to duration in interpretation of survival graphs. Risk Anal. 2005;25(3):589–95.

21.

Zikmund-Fisher

Fagerlin

Ubel

. Mortality versus survival graphs: improving temporal consistency in perceptions of treatment effectiveness. Patient Educ Couns. 2007;66(1):100–7.

22.

Fagerlin

Zikmund-Fisher

Ubel

. Helping patients decide: ten steps to better risk communication. J Natl Cancer Inst. 2011;103(19):1436–43.

23.

Reyna

. A theory of medical decision making and health: fuzzy trace theory. Med Decis Making. 2008;28(6):850–65.

24.

Zikmund-Fisher

Smith

Ubel

Fagerlin

. Validation of the Subjective Numeracy Scale: effects of low numeracy on comprehension of risk communications and utility elicitations. Med Decis Making. 2007;27(5):663–71.

25.

Fagerlin

Zikmund-Fisher

Ubel

Jankovic

Derry

Smith

. Measuring numeracy without a math test: development of the Subjective Numeracy Scale. Med Decis Making. 2007;27(5):672–80.

26.

Kazer

Bailey

Chipman

. Uncertainty and perception of danger among patients undergoing treatment for prostate cancer. BJU Int. 2013;111(3, Pt B):E84–91.

27.

Garcia-Retamero

Galesic

. Communicating treatment risk reduction to people with low numeracy skills: a cross-cultural comparison. Am J Public Health. 2009;99(12):2196–202.

28.

Stenmark

Blas

Halverson

Sandler

Feng

Hamstra

. Continued benefit to androgen deprivation therapy for prostate cancer patients treated with dose-escalated radiation therapy across multiple definitions of high-risk disease. Int J Radiat Oncol Biol Phys. 2011;81(4):e335–44.

Supplementary Material

Please find the following supplemental material available below.

For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.

For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.

0.00 MB

0.78 MB

0.79 MB

0.41 MB

0.86 MB

0.12 MB