What works in ASP? Time to Step up Our Game

Reviewed by Cynthia T. Nguyen, PharmD, University of Chicago Medicine and James “Brad” Cutrell, MD, FIDSA, UT Southwestern Medical School

As the threat of antimicrobial resistance and the need for antimicrobial optimization increase, antimicrobial stewardship programs (ASPs) are challenged with the need to practice more efficiently and prioritize high-yield interventions. Unfortunately, high-quality evidence evaluating the effectiveness of many core ASP practices and interventions are limited. 

Suzuki and colleagues published a multicenter retrospective cohort study comparing 3 different ASP strategies on carbapenem use at 90 Veterans Health Administration facilities. The 3 ASP strategies included: no strategy (NS), prospective audit and feedback (PAF) or restrictive policies (RP). The primary outcome was overall carbapenem days of therapy (DOT) per 1000 days present. Additionally, 425 cases were randomly selected to evaluate for antibiotic appropriateness. Overall, 429,062 admissions across 90 sites (58 RP, 24 NS, 8 PAF) were included. Carbapenem use was lower at PAF sites compared to NS sites and similar between RP and NS sites. Hospitals with carbapenem stewardship strategies (PAF or RP) had significantly more ID consultations for patients on carbapenems, and ID consultation was associated with more appropriate carbapenem prescribing, suggesting a role for ASPs and ID to work together to optimize carbapenem use. The findings are limited by the variable hospital complexity between comparator groups (e.g., lack of access to ID expertise among NS sites), which likely influences carbapenem prescribing practices. Still, these results are similar to previously published data suggesting that PAF alone may be a more effective ASP strategy compared to RP alone although the best approach likely includes a combination of both approaches.

Schuts and colleagues conducted an updated systematic review and meta-analysis of the impact of restriction of antimicrobial classes on antimicrobial resistance patterns. Including studies published from 1985 to June 2020, the authors found 15 studies from 11 countries with overall low quality of evidence based on the Cochrane Risk of Bias or Newcastle-Ottawa tools; key exclusions included studies that did not report both antimicrobial use and resistance data, studies from outpatient settings, outbreaks, or in pediatric populations. The most commonly restricted antimicrobial classes included carbapenems (6 studies), fluoroquinolones (FQ; 8 studies), and third generation cephalosporins (9 studies). In the meta-analysis, only two antibiotic-pathogen combinations showed a modest benefit on resistance associated with class-specific restrictive policies: a 23% decrease in resistance to FQs for non-fermenting Gram negatives and a 19% decrease in resistance to piperacillin-tazobactam for non-fermenters. Overall, a high degree of heterogeneity across studies and the small sample size and limited duration of some studies limited the ability to draw firm conclusions and highlight the limitations of the current ASP literature in this area.

Both of these studies highlight the urgent need and importance of high-quality studies to provide a solid evidence base for what ASP interventions provide the greatest benefit in reducing antimicrobial resistance and improving patient-relevant outcomes.


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