Treatment Persistence and Variations in Prescribing Oral, Injectable, and Inhaled Corticosteroids: A Population-Based Drug Utilisation Study.

PURPOSE: To examine variation in oral, injectable, and inhaled corticosteroid (CS) prescribing in primary care, exploring treatment persistence and coverage. METHODS: We examined patient-level electronic health records from English general practices in the Clinical Practice Research Datalink Aurum database. We delineated a cohort of new users of oral, injectable, or inhaled CS with prescriptions issued between January 1, 2000, and June 30, 2021. Lorenz curves assessed potential prescribing skewness, and Kaplan-Meier (KM) plots estimated treatment persistence. The Proportion of Patients Covered (PPC) method estimated the proportion of patients still covered by treatment 1 year after initiation. RESULTS: We observed 1 942 571 CS users across 1471 general practices, with 20% of oral and inhaled CS users accounting for almost 80% of total CS use. Older patients with comorbidities including respiratory diseases (13.5%), skin conditions (5.8%), or inflammatory bowel diseases (1.6%) were more likely to be prescribed higher doses. The KM plots showed that 20% of oral and 50% of inhaled CS users were persistent after one and 2 months, respectively. The PPC method indicated that 30% of oral and 60% of inhaled CS users were covered by treatment 6 months post-initiation. Some variation was observed when different grace periods were applied. Combined use of oral and inhaled CS was observed for 6.9% of patients. CONCLUSION: A fifth of patients receiving CS accounted for over 80% of oral and inhaled CS prescribing in primary care. Identifying these patients is crucial for targeting future interventions to promote patient safety and cost-effective CS use.