Objective: To identify predictors of compliance with antihypertensive combination therapy in a Medicaid population.
Methods: 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.
Inclusion: 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.
Results: 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.
Conclusion: Age, race, comorbidities, and simplified antihypertensive regimens were significant predictors of compliance. Higher compliance rates may enhance cardiovascular disease management outcomes.