New-user persistence with antihypertensives and prescription drug cost-sharing.

This study employed a new-user design to assess predictors of persistence with antihypertensive therapy, with emphasis on prescription drug cost-sharing. This retrospective longitudinal analysis used 2001-2002 claims data from 45 large health plans. The sample consisted of 23,047 individuals with hypertension, aged 41 to 65 years and receiving new antihypertensive treatment of angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, beta-blockers, calcium channel blockers, or diuretics. Prescription drug cost-sharing was measured as generosity ratio of actual to expected copayment. Other measures included demographics, Charlson comorbidity, type of health plan, and health care spending. Multivariate models showed that generous drug coverage was associated with an 11% to 19% increase in persistence (P<.05) in 4 of 5 antihypertensive drug classes compared with less generous drug coverage, controlling for the other measures. Less generous drug coverage is a risk factor for poor persistence among most new antihypertensive users.