THE IMPACT OF MULTIPLE CADIOVASCULAR MEDICATIONS USE ON MEDICATION ADHERENCE IN A CALIFORNIA MEDICAID POPULATION WITH CARDIOVASCULAR DISEASE

Purpose: To determine the impact of comorbid cardiovascular disease (CVD) and multiple cardiovascular medications on medication adherence in a California Medicaid population.  

Method: Eligibility and claims data (2002-2004) were used to identify adult patients (≥18 years of age) with a diagnosis of hypertension (HYPT), coronary artery disease (CAD), and/or heart failure(HF) and at least one prescription fill for a cardiovascular medication. Medication adherence was assessed based on proportion of days covered ≥0.8 using 2004 data.  Chi-square test was conducted to evaluate the univariate association of CVD condition (single and comorbid conditions) with number of CVD medications (1 vs. ≥2 medications). Multiple logistic regressions were used to determine predictors of medication adherence. 

Result: A total of 67,023 patients were identified (49% with HYPT, 10% with HF, 8% with CAD, 19% with HYPT+CAD, and 14% with HF+CAD).  Mean age was 66.2 (SD=13.3) years.  Patients with comorbid CVD were more likely to use multiple CVD medications [HF & CAD (88%), HYPT & CAD (78%)] than those with a single CVD diagnosis [HYPT (62%), CAD (73%), and HF (74%), respectively, p<0.0001]. Overall, the cardiovascular medication adherence rate was only 33%.  The significant predictors of medication adherence included a greater number of outpatient visits (OR=1.02, 95% CI: 1.02,1.03), greater number of cardiovascular medications (OR=1.39, CI: 1.37,1.41), no hospitalization (OR=1.55, CI: 1.47, 1.63), White race (OR=1.08, CI: 1.04,1.12), type of CVD (vs. HF) (CAD: OR=1.50, CI: 1.38, 1.63, HYPT+CAD: OR=1.39, CI:1.30,1.49, HYPT: OR=1.24, CI:1.17,1.33, HF+CAD: OR=1.164, CI:1.08,1.25), dual eligibility (OR=1.15, CI:1.11,1.20), no emergency department visit (OR=1.21, CI:1.14,1.28), and two or more comorbidities (OR=1.12, CI:1.07,1.18). 

Conclusion: California Medicaid patients with comorbid CVD were more likely to be using multiple cardiovascular medications than those with single CVD, especially those with hypertension. Overall, medication adherence was low. The patients with comorbid CVD as well as using multiple cardiovascular medications were more likely to be adherent. This may imply that these patients may have more severe CVD, which may increase adherence behavior in efforts to control patients’ symptoms.  Adherence interventions should focus not only on severe patients, but also on those with less severe disease and simpler regimens who may be at risk for developing multiple organ complications.