Impact of an Antimicrobial Stewardship Program on the Use of Carbapenems in a Tertiary Women's and Children's Hospital, Singapore

OBJECTIVES Antimicrobial stewardship programs (ASPs) promote the judicious use of antimicrobials by limiting inappropriate use. This article evaluates the impact of a prospective-audit-and-feedback ASP implementation on the appropriate utilization of carbapenems in a tertiary pediatrics and obstetrics/gynecology hospital in Singapore (KKH) after the establishment of an ASP in July 2011. METHODS This was a prospective, single-center, pre-post intervention study designed to analyze the appropriate prescribing of carbapenems pre-ASP (October 2009 to June 2011) and post-ASP (July 2011 to December 2013). Utilization of carbapenems was evaluated by daily defined doses (DDDs), days of therapy (DOTs), prescriptions, as well as cost per 100 patient-days pre-ASP and post-ASP using a segmented regression of interrupted time series analysis. RESULTS Of 404 prescriptions for carbapenems reviewed post-ASP, 70.3% were appropriate compared with those prescribed pre-ASP (55.9%; p=0.027). Reasons for inappropriate prescribing included inappropriate choice (36.1%) and duration (31.3%). A total of 61.2% of the interventions (213 of 348) were accepted. For pediatrics, there was a significant decrease in DDDs per 100 patient-days by 55.6% from a baseline of 0.9-0.4 (p=0.013) post-ASP and a reduction in DOTs per 100 patient-days by 46.7% from a baseline of 1.5-0.8 (p=0.06) post-ASP without significant changes in prescription rates. Pediatrics utilization cost increased from a pre-ASP mean of $175 per 100 patient-days to a peak of $238 (p<0.001) and decreased significantly post-ASP to a mean of $149 (p=0.01). For obstetrics/gynecology, there were no significant changes in DDDs (0.3 vs 0.3, p=0.99), DOTs (0.2 vs 0.3, p=0.36), prescriptions (0.03 vs 0.04, p=0.38), or cost ($45 vs $52, p=0.63) per 100 patient-days pre-versus post-ASP. CONCLUSIONS ASPs improved the appropriateness of carbapenems prescribing overall and reduced utilization in pediatrics. Identification of areas of inappropriate prescribing will be valuable in guiding future ASP efforts.