Using pharmacy claims data to evaluate adherence and persistence with prescribed medications in patients with diabetes mellitus

Background. Patients with diabetes mellitus often take prescription medications throughout their lives to maintain glycemic control and/or treat co-morbid conditions such as dyslipidemia. One important factor affecting the pharmacological management of glycemic control and dyslipidemia is adherence and persistence with treatment.; Objective. The objectives of this research were to (1) assess adherence with sulfonylureas using various measurements and evaluate the relationship between these measures; (2) evaluate adherence with lipid-lowering medications in patients; and (3) assess persistence with lipid-lowering medications. Patient- and medication-related characteristics that may influence medication adherence and discontinuation were examined.; Methods. Analyses were performed using pharmacy claims data. Adherence was measured by continuous and dichotomous measurements of medication availability, gaps in therapy, and surplus medication. Persistence was defined as continuation of therapy with sufficient medication to cover the observation period. Regression models were used to analyze the effect of patient- and medication-related characteristics on adherence and persistence.; Results. Sulfonylurea medication was available for an average of 89% of days during a 12-month period. This measure of medication availability correlated with measures of gaps in therapy and surplus medication. Rates of adherence were similar whether 9 or 12 months of prescription claims were examined, suggesting that an additional 3 months of data did not add any information to the assessment of medication adherence. No patient- or medication-related characteristics significantly influenced adherence with sulfonylureas (F5,987 = 0.59; p = 0.7065).; Adherence differed by the class of lipid-lowering medication prescribed at the index date. Adherent (≥80%) patients were less likely to be prescribed insulin therapy (OR = 0.304; 95% CI = 0.114, 0.815; p = 0.0180) and more likely to be prescribed statin medications (OR = 4.709; 95% CI = 0.996, 22.268; p = 0.0506) compared with non-adherent patients. No other study factors significantly influenced adherence with lipid-lowering therapy.; Overall, 58% of patients persisted with lipid-lowering medication. Compared with patients prescribed statins, patients prescribed non-statins were more than twice as likely to discontinue treatment (HR = 2.240; 95% CI = 1.260, 3.982; p = 0.0060).; Conclusions. These findings provide insight into adherence and persistence among patients with diabetes and highlight the need for health care providers to establish a partnership with patients to improve adherence and persistence with antidiabetic and lipid-lowering medications.