Impact of Regulatory Post‐Market Safety Advisories on Prescribing Practices: An Interrupted Time Series Analysis

Less frequent adverse drug reactions are usually discovered after a drug's release to the market, making effective and timely communication of regulatory post-market advisories essential for preventing emerging adverse effects. Time series analysis is a key study design for assessing the impact of post-market safety advisories. However, most previous studies have focused on narrow evaluations, limiting systematic assessment of how different safety advisories affect prescribing practices. This study aimed to investigate changes in prescribing practices following regulatory post-market safety advisories in Korea. Interrupted time series analyses were conducted using nationwide claims data from 2018 to 2021 and hospital datasets covering the period from 2 years before and 3 years after post-market safety advisories. We categorized the selected drugs into two groups: safety warning through letters and real-time safety alarms (contraindications or requiring attention). Twelve post-market safety advisories were analyzed, including four safety warnings and eight safety alarms, which showed an overall relative reduction (safety warning: relative change [95% confidence interval]: -8.06% [-10.23% to -5.84%], safety alarm on contraindication: -92.65% [-95.65% to -87.59%], and safety alarm on requiring attention: -8.04% [-9.98% to -6.05%]). All types of regulatory interventions reduced the prescribing of targeted drugs; however, the magnitude of these effects differed substantially depending on the type of intervention. By identifying and comparing the influence of regulatory post-market safety advisories, we can enhance these measures to better protect patient health. Continuous monitoring and systematic assessment of safety-related regulatory advisories, with ensured reproducibility, are warranted to optimize effectiveness and ensure safe medication practices.