Predictors of Compliance with Antihypertensive Therapy in a High-Risk Medicaid Population

Abstract

To identify predictors of compliance with antihypertensive combination therapy in a Medicaid population. Retrospective medical and pharmacy claims data for Maryland Medicaid patients receiving angiotensin converting enzyme inhibitors (ACEls)/hydrochlorothiazides (HCTZs) or ACEl/calcium channel blockers as fixed-dose combinations or separate agents during the period of January 1, 2002 to December 31, 2004, were analyzed. Continuously enrolled patients 18 years and older and at least one year of follow-up. Exclusion: Use of fixed-dose combination antihypertensives between January 1, 2002 and June 30, 2002 (to identify incident cohort). Compliance was defined as medication possession ratio greater than or equal to 80%. Multivariate logistic regression was used to predict compliance as a function of age, gender, race, comorbidities (Charlson Comorbidity Index [CCI]), and use of either fixed-dose combination or separate agents. There were 568 patients, 63.73% female, 68.83% African American, median age 52 years, 35.56% on fixed-dose combinations, 72.89% started on ACEI/HCTZ, and 24.82% complied with therapy. Patients younger than 40 years (OR, 0.38; p = .01; 95% CI, 0.18-0.81) and African American (OR, 0.45; p = .0004; 95% CI, 0.29-0.70) were less likely to be compliant than patients older than 60 years and Caucasian, respectively, Patients with a CCI of 1 (OR, 2.11; p = .05; 95% CI, 1.01-4.40) and those on fixed-dose combinations (OR, 1.60; p = .02, 95% CI, 1.06-2.40) were more likely to be compliant than those with higher CCIs and on separate agents, respectively. Age, race, comorbidities, and simplified antihypertensive regimens were significant predictors of compliance. Higher compliance rates may enhance cardiovascular disease management outcomes.