Associations of Renin‐Angiotensin System Antagonist Medication Adherence and Economic Outcomes Among Commercially Insured US Adults: A Retrospective Cohort Study

BACKGROUND: Medication non‐adherence can result in considerable morbidity, mortality, and costs. The Pharmacy Quality Alliance hypertension medication adherence measure is used by US healthcare payers and providers to assess renin‐angiotensin system antagonist medication adherence. However, associations between renin‐angiotensin system antagonist adherence as calculated in quality measures, and healthcare service use and expenditure in commercial populations over a 1‐year timeframe has not been assessed. METHODS AND RESULTS: This retrospective cohort study used eligible commercially insured individuals from the Truven Health MarketScan Commercial Claims and Encounters Research Databases (2009–2015). Generalized linear models with log link and gamma distribution (expenditure) or negative binomial distribution (usage) assessed relationships between hypertension adherence (≥80% proportion of days covered) and healthcare use and expenditures (in 2015 US dollars) while adjusting for covariates (age, sex, geographic region; health plan; Deyo‐Charlson Comorbidity Index, number of chronic medications, and treatment naivety). Beta coefficients were used to compute cost ratios and rate ratios. A total of 4 842 058 subjects were eligible; of those, 3 310 360 (68%) were adherent (adherent mean age 53.3±8.0 years, 55.9% men; non‐adherent mean age 50.3±9.1 years, 53.1% men). Adherence was associated with fewer inpatient (rate ratios, 0.612; 95% CI, 0.607–0.617) and outpatient visits (rate ratios, 0.995; 95% CI, 0.994–0.997); and lower total costs (cost ratios, 0.876; 95% CI, 0.874–0.878) compared with non‐adherence. Adherence was associated with lower average per member per month total costs ($97.98) compared with non‐adherence. CONCLUSIONS: Adherence to renin‐angiotensin system antagonists was associated with fewer outpatient and inpatient visits, and lower total costs compared with non‐adherence in a 1‐year time frame.