Health literacy and adherence to medical treatment in chronic and acute illness: A meta-analysis.

Objective: To use meta-analytic techniques to assess average effect sizes in studies of: (1) the correlation between patient health literacy and both medication and non-medication adherence, and (2) the efficacy of health literacy interventions on improving health literacy and treatment adherence.

Methods: PsychINFO and PubMed databases were searched (1948-2012). A total of 220 published articles met the criteria for inclusion; effect sizes were extracted and articles were coded for moderators.

Results: Health literacy was positively associated with adherence (r=0.14), and this association was significantly higher among non-medication regimens and in samples with cardiovascular disease. Health literacy interventions increased both health literacy (r=0.22) and adherence outcomes (r=0.16). Moderator analyses revealed greater intervention efficacy when health literacy and adherence were assessed using subjective measures compared to objective measures. Health literacy interventions had a greater effect on adherence in samples of lower income and of racial-ethnic minority patients than in non-minority and higher income samples.

Conclusion: This is the first study to synthesize both correlational and intervention studies examining the relationship between health literacy and adherence to both medication and non-medication regimens.

Implications: These findings demonstrate the importance of health literacy and the efficacy of health literacy interventions especially among more vulnerable patient groups.