Comparative analysis of calendar time-specific and conventional propensity score analysis for thiazolidinedione use in diabetes

Objectives To evaluate whether there are differences in propensity score (PS) and treatment effects estimated using conventional and calendar time-specific PS (CTS-PS) approaches. Methods A retrospective database analysis at a university-affiliated hospital in Thailand was used. Diabetic patients receiving glucose-lowering medications from July 2008 to June 2011 were included. Patients were categorized into those exposed and not exposed to thiazolidinediones (TZDs). PSs were estimated by using conventional PS and CTS-PS. In the CTS-PS, PS was separately estimated for three specific calendar time periods. Patients were matched 1:1 using caliper matching. The outcomes were cardiovascular and all-cause hospitalizations. The TZD and non-TZD groups were compared with Cox proportional hazard models.