Supply Chain Events and Risk of Drug Shortage in Canada

Importance: Drug shortages are an ongoing challenge in health care delivery. Research has focused on factors associated with manufacturer-level shortage reports; however, these reports do not reflect population-level drug availability. It is essential to determine the impact of supply chain events on trends in drug utilization and identify factors associated with decreases in use to ascertain shortage risk and inform future policy prioritization. Objective: To quantify incident shortages following Canadian supply chain events and determine drug characteristics associated with increased shortage risk. Design, Setting, and Participants: This matched cohort study analyzed monthly trends in drug purchasing of Canadian pharmaceutical products from the IQVIA MIDAS database from January 2017 to December 2021 with a 6-month follow-up. Data were analyzed from September 2023 to September 2024. Exposure: Reporting of a supply chain issue in Drug Shortages Canada. Main Outcomes and Measures: The main outcome was an incident shortage, defined as a decrease of 33% or more in purchase volume within 6 months following the supply chain issue. A logistic regression with random effects compared the odds of experiencing an incident shortage for cases and controls. A secondary outcome, shortage intensity, defined as the decrease in purchases multiplied by the duration, was analyzed using a zero-inflated beta regression with random effects. Results: Of 1591 drugs, 972 unique drugs (61%) were exposed to 1919 supply chain events. Incident shortages were observed in 11% of cases (216 drugs), compared with 7% of controls (1271 comparators). Drugs with baseline sales less than 100 000 (odds ratio OR, 4. 01; 95% CI, 3. 03-5. 30), anti-infective drugs (OR, 3. 07; 95% CI, 2. 33-4. 04), and over-the-counter drugs (OR, 3. 05; 95% CI, 2. 38-3. 90) had greater odds of experiencing an incident shortage. Schedule G drugs, which include controlled drugs (OR, 3. 61; 95% CI, 1. 66-7. 77), drugs with more than 25 unique products available (OR, 2. 86; 95% CI, 1. 89-4. 44), and those with equal dominance in both retail and hospital sectors (OR, 2. 43; 95% CI, 1. 93-3. 01) had the largest magnitudes of association with higher shortage intensity. Conclusions and Relevance: In this study of shortage incidence following Canadian supply chain events, 9 in 10 reported supply chain events did not experience true shortages. These findings highlight a need for a unified shortage definition focusing on real disruptions in supply and can be used to guide policies to manage drug shortages, improve patient outcomes, and enhance health care delivery.