Out-of-Pocket Costs and Antihypertensive Medication Use Among Veterans: A Natural Experiment

Blood pressure (BP) control remains suboptimal in the United States despite available low-cost antihypertensive medications. Even small out-of-pocket medication costs may contribute to adherence. We determined whether $0 versus >$0 out-of-pocket costs for antihypertensive medications is associated with differences in adherence, discontinuation, BP control, and cardiovascular outcomes.

We included veterans with newly diagnosed hypertension who initiated antihypertensive medication in the Veterans Health Administration from 2004 to 2022. A fuzzy regression discontinuity design with 2-stage residual inclusion leveraged differences in medication copay policy at a 50% service-connected disability threshold (≥50% service-connected disability: $0 out-of-pocket cost versus <50%: $8 monthly cost). Outcomes included 1-year medication nonadherence (proportion of days covered <80%), 1-year medication discontinuation (no medication in the final 90 days of the study year), 1-year BP control (systolic BP/diastolic BP <140/90 mm Hg and <130/80 mm Hg) and cardiovascular disease events (myocardial infarction, coronary revascularization, peripheral artery disease, or stroke).

Among 417 705 veterans (mean±SD age, 56 [13] years; 92% male; 61% non-Hispanic White), 296 432 (71%) had $0 out-of-pocket costs. Accounting for changes in eligibility for $0 copays at the 50% service-related disability threshold, $0 out-of-pocket costs were associated with lower odds of nonadherence (odds ratio [OR], 0.87 [95% CI, 0.81-0.94]) and medication discontinuation (OR, 0.77 [95% CI, 0.71-0.84]). One-year BP control <140/90 mm Hg or <130/80 mm Hg and cardiovascular disease events events were similar between groups.

Among veterans with newly diagnosed hypertension, modest out-of-pocket medication costs were associated with lower adherence and discontinuation. These findings can inform ongoing discussions regarding policy levers for improving hypertension outcomes.