Abstract
BACKGROUND: Medication adherence varies across socioeconomic and demographic groups. Prior work has examined these relationships in selected populations and with zip code-level socioeconomic measures, but less is known about adherence patterns across all medications when using more granular community measures and location proxies. OBJECTIVE: To quantify associations between socioeconomic, demographic, and medication class factors and outpatient medication adherence. METHODS: We conducted a retrospective cohort study of 1,252,986 outpatient medication orders for 189,832 adults placed at a large health system in the Mountain West (University of Utah Health) from January 1, 2022, to January 1, 2024. Pharmacy, electronic health record, and Surescripts data were used. Medication adherence (proportion of days covered) was modeled with multivariate β regression with covariates including insurance, race, sex, marital and employment status, medication class, and Social Vulnerability Index socioeconomic quartile. RESULTS: Medicaid (adjusted odds ratio [aOR] = 0.87, P < 0.001) or no insurance (aOR = 0.80, P < 0.001) were associated with lower adherence than commercial coverage, whereas Medicare was associated with improved adherence (aOR = 1.06, P < 0.001, when compared with commercial insurance). Black, Native Hawaiian/Pacific Islander, and American Indian/Alaska Native patients had lower adherence compared with White patients (aOR = 0.93, P < 0.001 and aOR = 0.96, P < 0.001, respectively). The most vulnerable Social Vulnerability Index quartile (Q4) modestly reduced adherence (aOR = 0.98, P < 0.001) compared with Q1. Antihypertensive, cholesterol-lowering, antidepressant, and heart failure drugs had markedly higher adherence (aORs 1.35-1.60, P < .01, when compared with other medication classes). CONCLUSIONS: Several individual-level factors had strong associations with adherence. Community-level socioeconomic vulnerability had a modest association.