Medication Nonadherence: The Role ofￂ Cost, Community, and Individual Factors

Objective To explain the association of out-of-pocket (OOP) cost, community-level factors, and individual characteristics on statin therapy nonadherence. Data Sources BlueCross BlueShield of Texas claims data for the period of 2008-2011. Study Design A retrospective cohort of 49,176 insured patients, aged 18-64 years, with at least one statin refill during 2008-2011 was analyzed. Using a weighted proportion of days covered ratio, differences between adherent and nonadherent groups are assessed using chi-squared tests, t-tests, and a clustered generalized linear model with logit link function. Principal Findings Statin therapy adherence, measured at 48 percent, is associated with neighborhood-level socioeconomic factors, including race/ethnicity, educational attainment, and poverty level. Individual characteristics influencing adherence include OOP medication cost, gender, age, comorbid conditions, and total health care utilization. Conclusions This study signifies the importance of OOP costs as a determinant of adherence to medications, but more interestingly, the results suggest that other socioeconomic factors, as measured by neighborhood-level variables, have a greater association on the likelihood of adherence. The results may be of interest to policy makers, benefit designers, self-insured employers, and provider organizations.