Functional health literacy and medication adherence in atrial fibrillation patients

Background Atrial fibrillation (AF) treatment requires strict, long-term adherence to oral anticoagulants (OACs) to decrease associated morbidity risks. Despite its importance, adherence varies widely; nonadherence contributes to life-threatening adverse outcomes and elevated costs. Health literacy (HL)—the ability to acquire, comprehend, evaluate, and apply health information—is an important, yet underestimated factor. Given conflicting evidence on the HL-adherence association in chronic diseases, this study investigated this relationship and influencing demographic/contextual factors in AF patients across Iran. Methods This descriptive-analytical cross-sectional, multicenter study was conducted in 2025 across Tehran, Kurdistan, and Kermanshah provinces on 407 adult AF patients receiving OAC therapy. Functional HL was assessed using the HELIA questionnaire; medication adherence was evaluated via MMAS-8. Analysis involved Pearson correlation, independent-samples t -tests, and multiple linear regression. Results Mean total HL score was 108.65 ± 30.96 (moderate); mean MMAS-8 was 2.61 ± 1.54 (relatively high adherence). Total HL demonstrated a significant negative correlation with MMAS-8 scores (r = −0.099, p < 0.05), indicating higher HL associates with improved adherence, driven primarily by the “Information” subscale (r = −0.172, p < 0.01). While males had significantly higher HL scores (p < 0.001), females showed better adherence (p = 0.045). Notably, older age was paradoxically linked to worse adherence in Kurdistan (r = 0.327, p < 0.01). In multiple linear regression adjusting for age, gender, and study site (R 2 = 0.214, p < 0.001), total HL emerged as a strong independent predictor of better adherence (β = −0.500, p < 0.001), alongside older age, female gender, and residing in Kurdistan (all p < 0.001). Conclusions Health literacy is a statistically significant, independent and modifiable predictor of medication adherence in Iranian AF populations. Efficacy is specific to functional information application, highlighting the need for interventions focused on practical skills. The complex age-gender interaction demonstrates how regional socioeconomic and cultural contexts affect the HL-adherence relationship.