Impact of the Saskatchewan seniors’ drug plan (SDP) to medication utilization and adherence among Saskatchewan residents

Abstract

Background: In 2007, Saskatchewan’s Ministry of Health launched the Seniors’ Drug Plan (SDP), whereby provincial beneficiaries at or above the age of 65 receive medications at a maximum self-payment of $15. The purpose of this study was to document the impact of the SDP using provincial health-administrative databases. Methods: Aggregate medication utilization and costs were described using the prescription drug database starting two years before the implementation of the SDP and continuing for two years after. Interrupted time series analysis using segmented regression models were developed to test the impact of the SDP. Also, the probability of achieving optimal medication adherence was examined among cohorts receiving medications after SDP implementation versus similar patients receiving medications before the SDP and also a group of patients <65 years who were not eligible for the SDP at all. The impact of the SDP on the outcome of optimal adherence was estimated using logistic regression models with generalized estimating equations (GEE). Results: Monthly government spending on medications increased by 47.5% following implementation of the SDP, while total medication dispensations only increased by 5.8%. The SDP was associated with more dispensations per month among prevalent users (+5.4%, 95% CI: 1.3% to 9.5%) but not incident users who did not receive the study medication in the previous 365 days (+1.3%, 95% CI: -8.0% to 10.7%). Similarly, the SDP did not appear to impact the use of blood-glucose-lowering agents, (-0.5%, 95% CI: -6.2% to 5.2%). A small but significant increase in the odds of optimal medication adherence was observed after the SDP compared with before (OR=1.08, 95% CI 1.04 to 1.11). However, the impact was only observed in prevalent users (OR=1.08, 95% CI 1.04 to 1.12), but not incident users (OR=1.05, 95% CI 0.98 to 1.13). Also, the impact of the SDP on medication adherence was not consistent for all medication classes examined. Discussion: In summary, the SDP resulted in substantially higher government investment into drug costs without a major effect on medication utilization and adherence. However, cost reduction for seniors must have provided substantial relief independent of the impact on adherence and utilization.