Health literacy, numeracy, and interpretation of graphical breast cancer risk estimates

Abstract

Objective: Health literacy and numeracy are necessary to understand health information and to make informed medical decisions. This study explored the relationships among health literacy, numeracy, and ability to accurately interpret graphical representations of breast cancer risk.

Methods: Participants (N=120) were recruited from the Facing Our Risk of Cancer Empowered (FORCE) membership. Health literacy and numeracy were assessed. Participants interpreted graphs depicting breast cancer risk, made hypothetical treatment decisions, and rated preference of graphs.

Results: Most participants were Caucasian (98%) and had completed at least one year of college (93%). Fifty-two percent had breast cancer, 86% had a family history of breast cancer, and 57% had a deleterious BRCA gene mutation. Mean health literacy score was 65/66; mean numeracy score was 4/6; and mean graphicacy score was 9/12. Education and numeracy were significantly associated with accurate graph interpretation (r=0.42, p<0.001 and r=0.65, p<0.001, respectively). However, after adjusting for numeracy in multivariate linear regression, education added little to the prediction of graphicacy (r(2)=0.41 versus 0.42, respectively).

Conclusion: In our highly health-literate population, numeracy was predictive of graphicacy.

Practice implications: Effective risk communication strategies should consider the impact of numeracy on graphicacy and patient understanding.

Fig. 1

Numeracy assessment: percent correct responses to numeracy questions (N = 120).

Fig. 2

Survey instrument: graph formats showing breast cancer risk for hypothetical cases.

Fig. 3

Graphicacy assessment: percent correct responses to survey instrument (N = 120).

Fig. 4

Relationship of numeracy to graphicacy (N = 120).