The impact of tightened prescribing restrictions on proton pump inhibitor use in Australia: An evaluation using interrupted time series analysis

Aim: In May 2019, Australia's Pharmaceutical Benefits Scheme (PBS) tightened the prescribing restrictions for publicly subsidized high and standard strength proton-pump inhibitors (PPIs). We aimed to determine the impacts on PPI use in Australia. Methods: Population-based interrupted time series analysis of PBS dispensing claims for a 10% sample of PBS-eligible Australian residents from January 2017 to December 2020 and national prescription and over-the-counter sales to pharmacies from January 2017 to October 2020. We examined trends in monthly PPI dispensings, switches from higher to lower strength formulations, and volume (kg) dispensed and sold. Results: From May 2019, we observed a small, immediate decrease (−7830 [95%CI: −8818 to −6842]) in standard strength PPI dispensings/month, which rebounded to exceed pre-intervention levels by December 2020. High strength dispensings decreased until the end of the study period to less than half their pre-intervention average/month; low strength dispensings/month increased until the end of the study period to more than double their pre-intervention average/month. We observed transient increases in switches to lower strength formulations post-intervention. The kilograms of PPIs sold/month followed a similar pattern to PBS kilograms dispensed/month with the exception of standard strength formulations where PBS dispensings decreased by −74 (95%CI: −93 to −55) but total sales remained unchanged (comprising PBS and private prescriptions, and over-the-counter sales). Conclusions: Tightened prescribing restrictions had an immediate and sustained impact on PPI use in Australia, with decreased high strength use and increased low strength use. Some patients likely switched to private market prescriptions for standard strength PPI, given the observed patterns in total volume sold/dispensed.