Effect of Combination Therapy on Adherence Among US Patients Initiating Therapy for Hypertension: a Cohort Study

New trial evidence suggests that many patients may require more aggressive pharmacologic management to achieve lower blood pressure goals. Especially when first initiating anti-hypertensive treatment, it is unknown whether starting patients on multiple medications may be better for long-term adherence and persistence compared with starting one medication. To examine contemporary patterns of anti-hypertensive therapy initiation and compare long-term adherence and persistence among patients initiating fixed-dose combinations and single anti-hypertensive therapies. Retrospective cohort study. Using claims from a large nationwide insurer, we identified all patients initiating oral hypertension treatment from 2009 to 2013. We categorized patients into three categories based on the number and type of anti-hypertensive medications they initiated: a fixed-dose combination, a multi-pill combination or a single therapy. The primary outcome was persistence to any anti-hypertensive medication, either the initiated medication or other anti-hypertensive, 12 months after initiation in administrative claims. We also measured adherence to at least one anti-hypertensive in the 12 months after initiation and refilling at least one anti-hypertensive medication as outcomes. Full adherence was defined as having 80% of potential days covered with medication. Multivariable modified Poisson regression models were used to examine the association between initiating a fixed-dose combination anti-hypertensive and medication outcomes. Of the 484,493 patients who initiated oral anti-hypertensives, 78,958 patients initiated fixed-dose combinations, 383,269 initiated a single therapy, and 22,266 initiated multi-pill combinations. Patients initiating fixed-dose combinations were 9% more likely to be persistent (relative risk [RR]: 1.09, 95% CI: 1.08-1.10) and 13% more likely to be adherent (RR: 1.13 95% CI: 1.11-1.14) than those who started on a single anti-hypertensive therapy. Refill rates were also slightly higher among fixed-dose combination initiators. Fixed-dose combination pills appear to enhance adherence and persistence to anti-hypertensive medications among commercially insured patients starting treatment compared with single therapy.