Adherence to a Fixed-Dose Combination of Rosiglitazone/Glimepiride in Subjects Switching from Monotherapy or Dual Therapy with a Thiazolidinedione and/or a Sulfonylurea

Abstract

In 2005, a fixed-dose combination therapy (FDCT) of rosiglitazone maleate and glimepiride became available for treatment of type 2 diabetes mellitus. It is hypothesized that FDCTs increase adherence by decreasing the number of required tablets. To assess changes in medication adherence and hemoglobin A(1c) (A1C) values in subjects switching from monotherapy with either a sulfonylurea or rosiglitazone or dual therapy with both to rosiglitazone/glimepiride FDCT. This retrospective database analysis included subjects with 1 or more prescription fills for rosiglitazone, a sulfonylurea, or rosiglitazone/glimepiride FDCT during the identification period of January 1, 2006, to September 30, 2006. Subjects were grouped according to baseline and follow-up period treatment regimens: sulfonylurea or rosiglitazone monotherapy switched to sulfonylurea and rosiglitazone dual therapy (Mono/Dual), monotherapy to rosiglitazone/glimepiride FDCT (Mono/FDCT), sulfonylurea and rosiglitazone dual therapy in both periods (Dual/Dual), and dual therapy to rosiglitazone/glimepiride FDCT (Dual/FDCT). The medication possession ratio (MPR) was calculated as a measure of adherence. The change in A1C from the baseline period to the follow-up period was assessed for each cohort. The study included 16,490 subjects. From baseline to follow-up, MPR decreased for both the Mono/FDCT cohort and the Mono/Dual cohort, but the magnitude of this decrease was less for the Mono/FDCT cohort (-0.02 vs -0.10; p < 0.001). Mean MPR significantly improved for the Dual/FDCT cohort compared with the Dual/Dual cohort (+0.10 vs +0.05; p < 0.001). The mean absolute A1C reduction did not differ significantly between the Mono/FDCT cohort (-1.08%) and the Mono/Dual cohort (-0.77%). Compared with the Dual/Dual cohort, the Dual/FDCT cohort experienced a greater absolute reduction in A1C (-0.06% vs -0.51%; p = 0.004). The results remained statistically significant in the multivariate model. Switching to rosiglitazone/glimepiride FDCT, in comparison with switching to dual therapy, was associated with improvements in medication adherence and glycemic control.