Characteristics of hospital medication waste according to ABC analysis: retrospective observational study

Objectives Medication waste in hospitals is an important issue. Previous studies have primarily focused on the frequency and reasons for medication disposal, whereas the application of purchasing-value-based prioritisation to discarded medications has received limited attention. This study aimed to classify discarded medications using ABC analysis and evaluate their associations with hospital wards and reasons for disposal. Methods A retrospective observational study was conducted using hospital medication disposal records between April 2024 and March 2025. Medications were classified into categories A, B and C using ABC analysis based on their annual purchasing values. Associations between ABC classification and hospital ward or reason for disposal were evaluated using the χ² test and adjusted residual analysis. The strength of the associations was assessed using Cramér’s V. Results A total of 1571 medication-level disposal records were identified, of which 1505 records could be assigned an ABC classification and were included in the analyses. Ward-based analysis showed that category A medications were significantly more frequent in surgical wards, category B medications in mixed-specialty wards and category C medications in the central pharmacy storage (χ²(16) = 155.48, p=6.47 × 10-25, Cramér’s V=0.227). Analysis by reason for disposal showed that category B medications were significantly associated with preparation errors and order changes, whereas category C medications were significantly associated with expiration (χ²(12) = 164.92, p=5.21 × 10-29, Cramér’s V=0.234). Heatmap analysis demonstrated distinct ward-specific disposal patterns, with expiration predominating in the central pharmacy storage and preparation errors, order changes and damage predominating in acute-care wards. Conclusions ABC analysis identified distinct patterns of medication waste according to hospital ward and reason for disposal while incorporating purchasing-value-based prioritisation. This approach may serve as a practical management tool for prioritising medication management, developing targeted waste-reduction strategies, and optimising healthcare resource allocation in hospital pharmacy practice.