Prescribing trends before and after implementation of an antimicrobial stewardship program

Objectives: Antimicrobial stewardship programs are recommended to reduce antimicrobial resistance by reducing inappropriate use of antimicrobials. We implemented an antimicrobial stewardship program and aimed to evaluate its effect on broad-spectrum antimicrobial use. Design, setting and participants: Observational study with historical control using interrupted time series analysis conducted in a tertiary referral hospital. Hospital inpatients prescribed restricted antimicrobials for non-standard indications, where approval had expired or without approval. Intervention: Baseline period of 30 months immediately followed by an 18-month intervention period commencing January 2011. Main outcome measures: Number and type of interventions made by antimicrobial stewardship team; monthly rate of use of broad-spectrum antimicrobial agents (in defined daily doses/1000 occupied-bed-days). Results: The antimicrobial stewardship team made 1104 recommendations in 779 patients during the 18-month intervention period. In 64% of cases, the recommendation was made to cease or de-escalate the antimicrobial therapy, or to change from intravenous to oral therapy. The introduction of the intervention resulted in an immediate 17% (95% Cl, 13%-20%) reduction in broad-spectrum antimicrobial use in the intensive care unit and a 10% (95% Cl, 4%-16%) reduction in broad-spectrum antimicrobial use outside the intensive care unit. Reductions were particularly seen in cephalosporin and glycopeptide use, although these were partially offset by increases in the use of beta-lactam-beta-lactamase inhibitors. Conclusions: The introduction of an antimicrobial stewardship program, including postprescription review, resulted in an immediate reduction in broad-spectrum antimicrobial use in a tertiary referral centre. However, the effect of this intervention reduced over time.