Treatment selection and medication adherence for stable angina: The role of area-based health literacy

Rationale, aims, and objectives: Clinical studies show equivalent health outcomes from interventional procedures and treatment with medication only for stable angina patients. However, patients may be subject to overuse or access barriers for interventional procedures and may exhibit suboptimal adherence to medications. Our objective is to evaluate whether community-level health literacy is associated with treatment selection and medication adherence patterns. Method: The sample included Medicare fee-for-service beneficiaries (20% random sample) with stable angina in 2007-2013. We used an area-level health literacy variable because of the lack of an individual measure in claims. We measured the association between (a) area-based health literacy with treatment selection (medication only, percutaneous coronary intervention [PCI], or coronary artery bypass grafting (CABG) surgery) and (b) area-based health literacy with medication adherence. We controlled for other factors including demographics, co-morbidity burden, dual eligibility, and area deprivation index. Results: We identified 8300 patients of whom 8.7% lived in a low health literacy area. Overall, 56% of patients received medication only, 28% received PCI, and 15% received CABG. Patients in low health literacy areas were less likely to receive CABG (−3.5 percentage points; 95% CI, −6.8 to −0.3) than were patients in high health literacy areas, but the significance was sensitive to specification. Overall, 81.5% and 71.5% of patients were adherent to antianginals and statins, respectively. Living in low health literacy areas was associated with lower adherence to antianginals (−3.3 percentage points; 95% CI, −6.1 to −0.6) but not statins. Conclusions: Low area-based health literacy was associated with being less likely to receive CABG and lower adherence, but the differences between low and high health literacy areas were small and sensitive to model specification. Individual factors such as dual eligibility status and race/ethnicity had stronger associations with outcomes than had area-based health literacy, suggesting that this area-based measure was inadequate to account for social determinants in this study.