Switching from multiple daily injections to CSII pump therapy: insulin expenditures in type 2 diabetes.

Abstract

OBJECTIVES: To identify variations in expenditures and utilization of insulin and other antidiabetes medications by comparing patients with type 2 diabetes mellitus using continuous subcutaneous insulin infusion (CSII) pump therapy versus multiple daily injection (MDI) therapy. STUDY DESIGN: Truven Health Analytics MarketScan Commercial Claims and Encounters Database and Medicare Supplemental Database for 2006 to 2010 were used in a difference-in-differences approach that took advantage of variation in the timing of the switch from MDI therapy to CSII pump therapy. METHODS: Continuous users of MDI therapy throughout the study period were compared with those who switched to the CSII pump therapy during this period. Specifications included: coefficient estimates from cross-sectional ordinary least squares (OLS) regressions with: 1) no additional controls, 2) controls for patient demographics and comorbidities, and 3) patient fixed effects. Propensity score matching at baseline mitigated concerns regarding patient selection bias. RESULTS: While insulin expenditures rose during the study period, switching to CSII pump therapy led to sizable reductions in insulin expenditures. This reduction in insulin expenditures due to switching varied between $657 (standard error [SE] $126; P<.01) and $1011 (SE $250.60; P<.01) per year. CONCLUSIONS: This study demonstrated a significant reduction in insulin expenditures among MDI patients who switched to CSII pump therapy at various times throughout the study period.