Medication Refill Patterns and Mortality in U.S. Adults Aged 85+: A Retrospective Medicare Cohort Study

BACKGROUND AND OBJECTIVES: The oldest-old (aged 85 and older) with hypertension face unique challenges in maintaining consistent medication refill patterns, yet their impact on mortality remains unclear. This study examines refill patterns as a marker of health vulnerability and mortality risk in Medicare beneficiaries to inform clinical interventions. RESEARCH DESIGN AND METHODS: We conducted a retrospective cohort study of 1,205,032 U.S. Medicare beneficiaries aged 85 and older with hypertension, using claims data from 2006 to 2021. Refill patterns for antihypertensive medications, including dihydropyridine calcium channel blockers (dCCBs), were assessed using 30-day gaps in prescription claims, modeled as a time-varying exposure. Secondary analyses evaluated statins and proton pump inhibitors (PPIs). Cox proportional hazards models estimated adjusted hazard ratios (aHRs) for all-cause mortality, with sensitivity analyses using a 60-day gap threshold. RESULTS: Among 1,205,032 individuals (median age 86; 69.6% women), consistent refill patterns were associated with reduced all-cause mortality across medication classes. Adherence to dCCBs was associated with a 65% lower mortality risk (aHR 0.35, 95% CI 0.34-0.35) in fully adjusted models. Statins (aHR 0.40, 95% CI 0.38-0.41) and PPIs (aHR 0.45, 95% CI 0.42-0.47) showed comparable associations. Sensitivity and subgroup analyses (aged ≥95) confirmed these findings, though associations likely reflect underlying health status and end-of-life care decisions. DISCUSSION AND IMPLICATIONS: In Medicare beneficiaries aged 85 and older, consistent medication refill patterns were associated with lower mortality, likely reflecting health resilience. Refill data may identify at-risk individuals for timely clinical interventions.