4CPS-196 Analysis of antibiotic consumption due to the implementation of front-end and back-end strategies of antimicrobial stewardship: an interrupted time series analysis

<h3>Background and Importance</h3> The inappropriate use of antibiotics significantly contributes to antimicrobial resistance (AMR), leading to side effects and high healthcare costs. In hospital settings, the best strategy to deal with AMR is the implementation of Antimicrobial Stewardship (AMS) programmes, which include various strategies, mainly categorised as front-end (FE) and back-end (BE), respectively restrictive and persuasive measures. A combination of these two strategies has proven effective in reducing the inappropriate use of antibiotics in this context. <h3>Aim and Objectives</h3> Assessment of changes in the quali-quantitative trends of antibiotic consumption (DDD/100 hospital days) before and after the implementation of front-end (FE) and back-end (BE) Antimicrobial Stewardship (AMS) strategies in a Teaching Hospital. <h3>Material and Methods</h3> In October 2023, were implemented both front-end (FE) and back-end (BE) strategies. The FE involves formulary restrictions on prescriptions and pre-authorisation revision of prescriptions in all the hospital departments. The BE consists of post-prescription monitoring of antibiotic therapies within a multidisciplinary team, in dedicated settings (e.g. two Medical Departments). The antibiotic consumption was analysed through the Interrupted Time Series Analysis, from January 2019 to September 2024, focusing on the variation before and after October 2023, both quantitatively (DDD/100 hospital days) and qualitatively (percentage of consumption based on the AWaRe classification) trends were reported. <h3>Results</h3> The total consumption of antibiotics has shown a slight increase from January 2019 to October 2023 (pre-intervention trend = +0.01 DDD/100 days per month) and a statistically significant decrease with the introduction of FE and BE (post-intervention trend = −1.26 DDD/100 days per month; p&lt;0.05). Moreover, post-intervention, there was a statistically significant decrease in Reserve antibiotics (−0.34% per month; p&lt;0.05) and a non-significant decrease in Watch antibiotics (−0.21% per month), alongside a significant increase in Access antibiotics (+0.55% per month; p&lt;0.05). <h3>Conclusion and Relevance</h3> As revealed by the literature and by our experience, the introduction of FE and BE interventions is effective in improving prescribing appropriateness and in the qualitative and quantitative use of antibiotics. In fact, the collaboration in a multidisciplinary team, including clinicians, pharmacists, microbiologists, and nurses, has been essential for the success of AMS initiatives, as it allows for an integrated and shared assessment of therapeutic choices. <h3>References and/or Acknowledgements</h3> <h3>Conflict of Interest</h3> No conflict of interest