Effect of antihypertensive medication adherence among employees with hypertension.
To determine if antihypertensive medication adherence is associated with decreased medical and drug costs, medical service utilization, and work absence days. Retrospective database study using medical, pharmacy, sick leave, short-term and long-term disability, and workers' compensation claims data from multiple large US employers from 2001 to 2008. We used medical and pharmacy claims to identify employees with hypertension. The index date was the date of the first hypertension-related pharmacy claim. Eligible employees had health plan enrollment 6 months before the index date and at least 12 months after the index date. Employees younger than 45 years were excluded from the study. Regression models estimated the effect of the proportion of days covered (PDC) by hypertension medication on outcomes after the index date, including health benefit costs, medical service utilization, and work absence days, as well as some clinical outcomes calculated separately for high-prior-cost and low-prior-cost employees. High-prior-cost employees were those who accounted for the top 60.0% of total medical costs during the 6 months before the index date. The regression models controlled for demographics, job-related variables, and comorbidities. Among low-prior-cost employees, high PDC was associated with increased medical and drug costs and work absence days. Among high-prior-cost employees, high PDC was associated with decreased medical and drug costs, fewer work absence days and inpatient hospital days, and increased hypertension-specific medical costs. Antihypertensive medication adherence was associated with improvement in some short-term utilization measures among high-prior-cost employees, but significant short-term improvement was not seen among low-prior-cost employees.