Economic impact of pharmacist-led initiatives to minimize medication wastage costs in the hospital setting: an interrupted time series analysis

Abstract Background Medication wastage poses significant economic challenges to hospital management worldwide. To address this issue, in October 2020, we implemented comprehensive pharmacist-led initiatives focusing specifically on expired drugs and high-cost medications. This study aimed to evaluate the long-term economic impact of these initiatives using an interrupted time series analysis. Methods The comprehensive pharmacist-led initiatives comprised five operational components: proactive deletion of dormant medications from the adoption list, standardization of return and exchange procedures, establishment of a “just-in-time” procurement category, targeted promotion of high-cost near-expiry drugs, and mandatory submission of “High-Cost Medication Waste Reports”. This study compared a 36-month pre-intervention period (October 2017 to September 2020) with a 48-month post-intervention period (October 2020 to September 2024). The primary outcome was the change in total monthly medication wastage costs, evaluated by level change and slope change. Cumulative cost savings over the 48-month post-intervention period were estimated by comparing observed costs with predicted counterfactual values. Secondary outcomes included wastage costs categorized by reason and changes in high-cost medication wastage (50,000 Japanese yen [JPY] or more per case). Results No significant level change was observed in total monthly medication wastage costs; however, the slope change was significant (β 3 = -21,766 JPY/month; 95% confidence interval [CI]: -37,999 to -5,532; p = 0.0092). The estimated cumulative cost savings over the 48-month period following the intervention were 38,455,782 JPY. In the analysis by reason, expired drugs showed a significant slope change (β 3 = -23,820 JPY/month; 95% CI, -34,530 to -13,111; p < 0.0001). For high-cost medications, we found significant reductions in wastage costs (β 3 = -20,001 JPY/month; 95% CI, -35,864 to -4,137; p = 0.0141) and the frequency of wastage (incidence rate ratio = 0.977; 95% CI, 0.955 to 0.998; p = 0.0355). Conclusions Pharmacist-led initiatives focusing on expired and high-cost medications are economically effective, leading to a substantial reduction in hospital medication wastage costs. Pharmacists can enhance hospital financial sustainability by effectively mitigating avoidable medication-related economic losses.