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

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 I-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 greater than or equal to2 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 followup, 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 or their regimen (except discontinuation of therapy). Among these patients, those taking metformin or sulfonylurea alone had similar to 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.