Evaluation of compliance and health care utilization in patients treated with single pill vs. free combination antihypertensives

Objectives: To compare compliance/persistence, health care resource utilization, and costs associated with single-pill combination (SPC) vs. free-combination (FC) therapies among adult hypertension patients at the national and state level. Combination therapies with angiotensin receptor blocker (ARB) + calcium channel blocker, ARB + hydrochlorothiazide, and angiotensin-converting enzyme inhibitor + hydrochlorothiazide were evaluated. Methods: Patients initiated on SPC or FC were identified in the MarketScan Database (2006-2008). Multivariate regression models were used to compare the health care outcomes of SPC vs. FC use during the 6-month study period. National-and state-level outcomes were analyzed and reported. Compliance was measured by medication possession ratio (MPR), and persistence was assessed based on treatment discontinuation (i.e., a lapse in therapy exceeding 30 days). Utilization and cost outcomes included frequencies of inpatient and emergency room (ER) visits and changes in health care costs from baseline. Results: Adjusting for baseline characteristics, SPC patients (N - 382,476) demonstrated significantly higher MPR than FC patients (N - 197,375) (difference = 11.6%; 95% confidence interval [CI]: 11.4%, 11.7%). SPC patients had fewer all-cause hospitalizations (adjusted incidence rate ratio [IRR] 0.77; 95% CI: 0.75, 0.79) and ER visits (adjusted IRR 0.87; 95% CI: 0.86, 0.89) than FC patients. Results for cardiovascular-related utilization were similar to all-cause results. Compared to FC, SPC patients showed significantly greater reductions post-therapy initiation in all-cause medical costs by -$208 (95% CI: -$302, -$114), but larger increases in hypertension-related prescription costs by $53 (95% CI: $51, $55). State-level results were generally consistent in magnitude and direction for comparisons of compliance and utilization, with greater regional variation in costs. Limitations include the possibility of residual confounding from factors not observable in claims. Conclusion: SPC use was associated with significantly better compliance/persistence and fewer hospitalizations and ER visits than FC in hypertensive patients at the national level and in almost all states. Larger reductions in medical costs with SPC use more than offset higher drug costs within most states.