(P-527) Evaluating the Impact of New Prescribing Restrictions for Publicy-subsidised Proton Pump Inhibitors in Australia: An Interrupted Time Series Analysis

Background: In May 2019 tightened prescribing restrictions were introduced for proton-pump inhibitors (PPIs) publicly-subsidised through the Pharmaceutical Benefits Scheme (PBS), requiring prescribers to obtain permission from the Australian government to prescribe high and standard strength PPIs. The impact of these restrictions on PPI use in Australia is not yet known.

Objectives: To evaluate the impact of tightened prescribing restrictions on use of PPIs in Australia.

Methods: We used dispensing records from national 10% sample of PBS beneficiaries and national pharmaceutical sales data to examine trends is PPI dispensings, PPI sales, treatment discontinuation per 10,000 treated, and switches from higher to lower strength formulations per 10,000 treated between January 2016 and December 2019. We used interrupted time series analysis to quantify changes in each outcome following implementation of the restrictions.

Results: Dispensings for all PPIs fell by a sustained 6% in May 2019, led largely by a 15% decrease in dispensings of high strength formulations. Standard strength dispensings decreased by 4%, while dispensings of low strength PPIs increased by 16% in May 2019 and 5% each month thereafter. Sales of PPIs to pharmacies followed a similar pattern for high and low strength formulations, while there was no change in sales of standard strength PPIs. PPI discontinuations per 10,000 increased for all strengths in May 2019 and declined for high strength PPIs by 83/10,000 each month thereafter. Switches to lower strength formulations increased during May and June 2019 by 142/10,000 and 39/10,000, respectively, decreasing each month thereafter by 24/10,000.

Conclusions: Tighter prescribing restrictions resulted in significant changes to PPI use in Australia. High strength PPI use declined as people switched to standard strength formulations or discontinued treatment, while use of low strength PPIs increased substantially. Some PBS beneficiaries and prescribers may have switched to private market prescriptions to avoid the new PBS restrictions, given the sales of standard strength PPIs did not change. Overall, our findings suggest the immediate impacts of the policy changes have enhanced the quality use of PPIs in Australia.