Background: Statin adherence is a serious problem in patients with hyperlipidemia. However, it is not clear whether statin adherence is associated with medical utilization or health-care costs.
Objective: To study statin adherence and assess associated medical utilization and health-care costs in patients with type 2 diabetes, based on a national Medicaid database.
Methods: A retrospective claims-based study was conducted using the records of patients with type 2 diabetes with comorbid hyperlipidemia who were continuously enrolled in Medicaid from January 2004 to December 2006. All data were drawn from MarketScan Medicaid Database, including inpatient, outpatient, and drug claims. The eligible patients starting statins in 2005 were followed for 1 year to measure medication use, hospitalization, outpatient visits, emergency department (ED) visits, and health-care costs based on Medicaid medical and drug claims. Adherence was measured by medication possession ratio (MPR). Multiple regression analyses were implemented to assess statin adherence-associated outcomes, including medical utilization (risks for hospitalization and ED visits), all-cause costs, and hyperlipidemia-related medical costs.
Results: A total of 1705 eligible patients with type 2 diabetes and hyperlipidemia were identified. The average adherence rate to statins (MPR) at 1 year was 0.61, and 37% of the patients (n=624) were adherent to statins (MPR≥0.8). Regression analyses indicated that diabetic patients who were adherent to statins showed lower risks for hospitalization (OR 0.80; 95% CI 0.636 to 0.966) and ED visits (OR 0.71; 95% CI 0.519 to 0.812) and decreased all-cause medical costs by 15% (p<0.05) and hyperlipidemia-related medical costs by 12% (p<0.05).
Conclusions: Our study found high prevalence of nonadherence to statins in Medicaid patients with type 2 diabetes. Adherence to statins (MPR≥0.8) was associated with reduced medical utilization and lower medical costs.