Patterns of nonadherence to antihypertensive therapy in primary care.

Nonadherence to medications is an important cause of poor blood pressure control. Long-acting antihypertensive agents could theoretically be beneficial in partially adherent patients, who are commonly seen in contemporary practice. Little has been reported about the duration of drug holidays (DHs) in treated hypertensives outside of generally compliant patients in phase 4 clinical trials. The authors described patterns of nonadherence to single and multiple antihypertensives in a random sample of 120 primary care patients with uncontrolled hypertension. Adherence to up to 3 antihypertensives was measured by electronic monitoring. Frequencies of single-day omissions and DHs of 2 consecutive days (DH2), 3 days (DH3), or ≥4 days (DH≥4) for each drug were calculated. Overall, 89 (74%) of patients had at least a 1-day omission. A single day omission was found in 61.4% of the patients taking 1 drug, followed by DH≥4 (28.1%), DH2 (26.3%), and DH3 (8.8%). In patients using multiple drugs, single-day omissions were also most common, followed by DH≥4, DH2, and DH3. Omissions of ≤3 days comprise on average 74% of all omissions. Although encouraging full adherence remains important, it may be prudent to prescribe long-acting antihypertensive agents, which can compensate for the majority of dose omissions.