Assessing the impact of discontinuation of formulary prior authorization on antibiotic prescribing.

Objective: To compare prescribing patterns of restricted antimicrobials before and after the removal of prior authorization and to develop a prospective audit and feedback program to mitigate the potential inappropriate prescribing of these antimicrobials.

Methods: An interrupted time-series analysis assessing the trends in antibiotic use was conducted between May 2020 and February 2023 in large urban hospitals, where all ASP activities were discontinued in May 2022 and a pilot prospective audit and feedback (PAF) program was initiated in January 2023.

Results: The collective change in restricted antibiotic utilization after the removal of prior authorization was trending towards increased utilization but was not statistically significant. With the PAF program, 9.8% of patients were identified by the antimicrobial stewardship pharmacists as requiring intervention. Within these patients, 19 different recommendations were made, with the most common being to narrow the therapeutic spectrum (47.4%). Stewardship interventions suggestions were accepted (full and partial) 69.2% of the time.

Conclusions: Although there were some small statistically significant changes detected for a few antibiotics, there were no situations where those changes remained significant after appropriate controls were added to the analyses. As such, the intervention may not have had any statistically significant impact on DDDs of the studied antibiotics.