Adherence with statins over 8 years in a usual care setting

Objective: To describe adherence with statin treatment in a usual practice setting and to investigate potential determinants of better adherence. Study Design: Retrospective cohort study using administrative claims data. Methods: Study patients were 47,680 individuals enrolled in the Central District of Clalit Health Services HMO in Israel who filled at least 1 prescription for statins between January 1, 1999, and December 31, 2006. Data were retrieved on patients' sex, year of birth and immigration, socioeconomic status, and whether they had diabetes mellitus, hypertension, and other cardiovascular diseases. Results: Mean age at the beginning of treatment was 61.3 ± 11.8 years; 53.3% of the study patients were women. The proportion with at least 1 chronic disease before starting statins was 40.1%; and 38.9%, 21.8%, and 9.6% of the patients were continuously adherent after 1, 3, and 6 years, respectively. Risk of discontinuation was highest among new immigrants (hazard ratio [HR] = 1.20; 95% confidence interval [CI] = 1.14, 1.27). Adherence was higher in patients having a chronic disease before starting statins (HR = 0.88; 95% CI = 0.84, 0.94) or after starting statins (HR = 0.90; 95% CI = 0.86, 0.95). Patients age <50 or >79 years had lower adherence rates. Low socioeconomic state did not affect adherence. Conclusions: Adherence with statin therapy was poor, though adherence rates were better in patients with accompanying chronic diseases. Of particular concern was the low level of adherence in new immigrants. Intervention programs are needed and should target all patient groups.