Background: Diabetes patients are usually at increased risk of developing cardiovascular diseases (CVDs). The treatment with statins is known to reduce cardiovascular risk in the secondary prevention of CVDs. Several observational studies have shown that the patients on statin therapy have low adherence. Low adherence is an important issue which has serious health implications like increased morbidity and mortality.
Objectives: The main objectives of this study were to determine the adherence with statins among the University of Toledo (UT) employees and their dependents with diabetes and to study the effects of independent variables [age, co-payment, gender, location (main vs. health science campus), and adherence with the diabetes medications] on adherence with statins.
Methods: This study was a retrospective, longitudinal observational study. UT employees and their dependents pharmacy claims data was used for the study. Adherence with statins was determined in 180 day and one year observation periods for those patients who filled prescriptions for statins in addition to prescriptions for oral hypoglycemic drugs (OHDs) during the study period. Medication possession ratio (MPR) for statins was calculated and used as the dependent variable (MPR < 80% - non-adherent, MPR >= 80% - adherent). Descriptive statistics were used to describe the study population. Logistic regression was used to study the effects of independent variables on adherence with statins.
Results: One hundred and ninety-three patients were included in the 180 day analysis, while 150 patients were included in the one year analysis. The mean adherence with statins was 0.80 and 0.78 over the 180 day and one year observation periods, respectively. About 64% of patients were adherent to statin medications with MPR ≥ 80% during the 180 day observation period. This adherence rate decreased to 60% of patients at the end of one year. In the regression model, adherence with diabetes medications was significantly positively related with adherence with statin medications.
Conclusion: Adherence with statins was found to be suboptimal among the study population. This presents an increased risk of developing cardiovascular complications among this population, which can lead to increases in the healthcare costs for the university. The university should further investigate the reasons for non-adherence in this population and interventions should be designed to improve adherence. Improved adherence can help in reducing overall healthcare cost for this self-insured organization.