While clinical trials demonstrate the benefits of blood pressure and cholesterol reduction, medication adherence in clinical practice is problematic. We hypothesized that a single-pill would be superior to a 2-pill regimen for achieving adherence. In this retrospective, cohort study based on pharmacy claims data, patients newly initiated on a calcium channel blocker (CCB) or statin simultaneously or within 30 days, regardless of sequence, were followed (N=4703). Adherence was measured over 6 months as proportion of days covered (PDC). At baseline, mean age was 63.0 years, 51.6% were female, and mean number of other medications was 7.8. Overall, 16.9% of patients were on single-pill amlodipine/atorvastatin, 15.6% amlodipine + atorvastatin, 24.7% amlodipine + other statin, 13.9% other CCB + atorvastatin, 28.9% other CCB + other statin. Percentages of patients achieving adherence (PDC >or= 80%) were: 67.7% amlodipine/atorvastatin; 49.9% amlodipine + atorvastatin; 40.4% amlodipine + other statin; 46.9% other CCB + atorvastatin; 37.4% other CCB +other statin. After adjusting for treatment selection and cohort differences, odds ratios for adherence with amlodipine/atorvastatin were 1.95 (95% confidence interval [CI], 1.80-2.13) vs amlodipine + atorvastatin, 3.10 (95% CI, 2.85-3.38) vs amlodipine + other statin, 2.06 (95% CI, 1.89-2.24) vs other CCB + atorvastatin, 2.85 (95% CI, 2.61-3.10) vs other CCB + other statin (all p<0.0001). Single-pill amlodipine/atorvastatin may provide clinical benefits through improving adherence, offering clinicians a practical solution for cardiovascular risk management.
Keywords: adherence; amlodipine besylate; atorvastatin calcium; persistence.