BACKGROUND: Given that Korea lacks measures to promote cost-effective prescribing, this study investigated the efficiency of prescribers' decision-making when faced with the choice of 398 products containing 15 proton pump inhibitors (PPI). OBJECTIVE: This study aimed to explore PPI prescribing patterns in ambulatory care over 10 years and elucidate prescribers' practices. Further analysis was conducted to estimate the achievable potential savings, assuming that the recommendation of first-choice drugs is based on the rational use of medicines. METHODS: Retrospective PPI prescribing data from the ambulatory sector pertaining to medical services provided to the entire South Korean population from 2013 to 2022 were extracted from the Korean National Health Information Database
the data were analyzed to identify annual trends in PPI spending and utilization volume according to defined daily doses (DDDs). Unit price per DDD was calculated, and a preferred cost-effective choice with identical efficacy and safety profile was selected among PPIs. The potential savings were then simulated using Dirichlet distribution. RESULTS: In ambulatory care, PPI drug costs increased by 13.0% per annum over 10 years. The preferred substances were esomeprazole (31.6%), rabeprazole (23.2%), and tegoprazan (16.5%), which are among the most expensive PPIs. However, the most cost-effective substance was dexlansoprazole (South Korean won [KRW] 522.7
standard deviation [SD] = 72.2
and median = 583). If dexlansoprazole is recommended as the first-choice PPI in the Korean context, the estimated cost savings would be 404.24 billion KRW, equivalent to 47.0% of the current PPI spending in ambulatory care. CONCLUSIONS: This study identified opportunities for substantial cost savings related to PPI prescribing. Guided decision-making toward cost-effective PPI prescribing would increase the efficiency of prescribing and the sustainability of the healthcare system.