METHODS: Using existing electronic health record data from fiscal year (FY) 2015, we described population adherence to prescribed antihypertensive medications for the Central Alabama Veterans Health Care System (CAVHCS). Adherence was defined for each Veteran as having ≥80% of days covered by an antihypertensive medication from the date of first prescription fill. BP control was defined as the last three recorded measurements averaging <140 systolic and <90 diastolic.
RESULTS: For FY 2015, there were 33 different antihypertensive medications dispensed through 79,178 outpatient medication fills to 17,889 patients at CAVHCS. The mean number of unique medications dispensed to a patient during the year was 1.8 (median 2, range 1–7). Nearly half of patients (45.2%) received only one class of antihypertensive, 35.4% received two classes, and 16.0% received three classes. Overall, 75.1% of patients were considered adherent to antihypertensive medication. Additionally, 66.1% were considered to have adequate BP control. Patients considered adherent to medication were 1.09 (95% confidence interval: 1.06–1.12) times more likely to have adequate BP control compared with patients considered to be nonadherent (67.4% vs. 62.0%, p<0.0001). Among patients who had uncontrolled BP, 73.6% were considered adherent to medication, compared with 78.0% among those with controlled BP (p<0.0001). With increasing number of antihypertensive classes prescribed per patient, adherence increased, but proportion controlled decreased. In a logistic regression model controlling for age, body mass index, number of antihypertensive medications, and number of antihypertensive drug classes, adjusted odds of BP control was 1.33 times higher (95% CI 1.22–1.44) for those adherent to BP medication compared with those who were nonadherent.
CONCLUSIONS: Adherence to antihypertensive medication was associated with improved BP control; however, a substantial proportion of patients with inadequate BP control were also considered adherent. Interventions to increase BP control could not only address improved medication adherence, but also closer monitoring of BP, targeted education regarding lifestyle modification, and more aggressive medication adjustment when needed to achieve blood pressure goals.