Patient compliance and persistence with antihyperglycemic drug regimens: evaluation of a medicaid patient population with type 2 diabetes mellitus

Abstract

Background: Drug use patterns among patients with type 2 diabetes mellitus have been studied in the general population but not specifically in the Medicaid population. Objective: The purpose of this study was to examine antihyperglycemic drug use patterns among Medicaid recipients with type 2 diabetes and assess patients' persistence and compliance with different antihyperglycemic drug regimens. Methods: Pharmaceutical claims data from Medi-Cal for January 1996 through September 1998 were analyzed to investigate antihyperglycemic drug use patterns over a 1-year and 2-year period. Prescription refill data were examined to assess patient compliance and persistence. Results: Of the 37,431 patients in the 1-year follow-up cohort, 79.6% started antihyperglycemic treatment with monotherapy (ie, drug therapy with a single class of antihyperglycemic medication), 14.5% with insulin alone, 3.9% with polytherapy (ie, drug therapy with ≥2 classes of medication other than insulin), and 2.1% with insulin plus another therapy. Of the patients receiving monotherapy, 85.3% were taking a sulfonylurea, 14.0% were taking metformin, and 0.7% were taking another agent. In the 1-year follow-up, 55.5% of patients taking metformin alone, 67.2% of those taking sulfonylurea alone, and 83.9% of those taking metformin plus sulfonylurea (M + S) did not undergo any modification of their regimen (except discontinuation of therapy). Among these patients, those taking metformin or sulfonylurea alone had ∼65% more days of continuous (or persistent) treatment (129 and 128 days, respectively) per patient per year than did patients taking polytherapy (78 days). In addition, sulfonylurea or metformin monotherapy was associated with a 36% higher compliance rate than M + S polytherapy (177 days vs 130 days). Conclusion: Simple 1-drug antihyperglycemic regimens were associated with better compliance and persistence (as measured by prescription refill data) than more complex multiple-drug regimens among patients with type 2 diabetes in the Medi-Cal population.