Safety of a Carbapenem Restriction Policy in Patients with Gram-Negative Bacteremia

BACKGROUND: Antibiotic restriction policies may decrease antimicrobial use and reduce resistance rates. However, it is unknown whether they inadvertently harm patients. We evaluated whether the implementation of a carbapenem restriction policy led to adverse patient outcomes. METHODS: A carbapenem restriction policy was implemented at the University of Washington Medical Center on 11/1/15. This policy required Infectious Disease consultation for meropenem and imipenem use beyond 72 hours (except for cystic fibrosis and neonatal patients). We conducted retrospective chart review on all inpatients with Gram-negative bacteremia and compared outcomes between the pre- and post-restriction periods. Medical records were reviewed for culture, antibiotic, APACHE score, and patient outcome data. Primary outcomes were (1) time from blood culture to effective antibiotic therapy and (2) number of drug-bug mismatches (DBM). Secondary outcomes included (1) inpatient mortality, (2) length of stay (LOS), (3) whether sepsis resulted in transfer to the intensive care unit (ICU), and (4) ICU LOS. RESULTS: There were 153 patients in the pre-restriction group and 163 in the post-restriction group. The mean time to effective antibiotic was 11.1 and 14.9 hours in the pre- and post-restriction groups, respectively (P = 0.13), with median times of 2.8 and 3.3 hours. DBM occurred in 12% of cases before the restriction and 19% after (P = 0.11). Hospital mortality rate was 16% pre-restriction and 17% post-restriction (P = 0.7). ICU transfer due to sepsis occurred in 12% of cases pre-restriction and 17% post-restriction (P = 0.3). There was a significantly longer mean LOS post-restriction (adjusted difference 6.7 days, P = 0.01). Among patients with ICU days >0, mean ICU LOS was 1.2 (95% CI: -1.6 to 4.3) days shorter before the restriction (P = 0.2). CONCLUSION: When carbapenem use was restricted, there was no statistically significant or clinically meaningful difference in time to effective antibiotic therapy, percent of DBM, hospital mortality, or ICU transfers. There was a statistically significant increase in mean LOS post-restriction in the adjusted analysis, which may not be clinically important. We conclude that carbapenem restriction may be safe, and we plan to continue this policy at our institution. DISCLOSURES: All authors: No reported disclosures.