Copayment level, treatment persistence, and healthcare utilization in hypertension patients treated with single-pill combination therapy

Abstract

Objectives:To evaluate the relationship between drug copayment level and persistence and the implications of non-persistence on healthcare utilization and costs among adult hypertension patients receiving single-pill combination (SPC) therapy.Methods:Patients initiated on SPC with angiotensin receptor blocker (ARB) + calcium channel blocker, ARB + hydrochlorothiazide, or angiotensin-converting enzyme inhibitors + hydrochlorothiazide were identified in the MarketScan Database (2006–2008). Multivariate models were used to assess copayment level as a predictor of 3-month and 6-month persistence. Three levels of copayment were considered (low: ≤$5, medium: $5–30, high: >$30 for <90-day supply; low: ≤$10, medium: $10–60, high: >$60 for ≥90-day supply). Separate models examined the implications of persistence during the first 3 months on outcomes during the subsequent 3-month period, including utilization and changes in healthcare costs from baseline. National- and state-level outcomes were analyzed.Results:Analyses of 381,661 patients found significantly lower 3-month and 6-month persistence to therapies with high copayments. Relative to high-copayment drugs, risk-adjusted odds ratios at 3 months were 1.29 (95% confidence interval [CI]: 1.26, 1.32) and 1.27 (95% CI: 1.24, 1.30) for low- and medium-copayment medications, respectively. The strength of the association between copayment and persistence varied across states. Non-persistent patients had significantly more cardiovascular-related hospitalizations (incidence rate ratio [IRR] = 1.36; 95% CI: 1.30, 1.43) and emergency room (ER) visits (IRR = 1.51; 95% CI: 1.43, 1.59) than persistent patients. Non-persistence was associated with significantly larger increases in all-cause medical services cost by $277 (95% CI: $225, $329), but lesser increases in prescription costs by –$81 (95% CI: –$85, –$76).Limitations:Limitations include the possibility of confounding from unobserved factors (e.g., patient income), and the lack of blood pressure data.Conclusions:High copayment for SPC therapy was associated with significantly worse persistence among hypertensive patients. Persistence was associated with substantially lower frequencies of hospitalizations and ER visits and net healthcare cost savings.