Impact of a program combining pre-authorization requirement and post-prescription review of carbapenems: an interrupted time-series analysis

The objective of this study was to assess the impact on carbapenems use of a program combining pre-authorization requirement and systematic post-prescription review of carbapenems prescriptions. The program was implemented in a 1,230-bed teaching tertiary hospital. Monthly carbapenems consumption was analyzed using a controlled interrupted time-series method and compared to that of vancomycin before and after implementation of the intervention. Compared to the pre-intervention period (14 monthly points), a significant and sustained decrease of carbapenems consumption [1.66 defined daily doses (DDD)/1,000 patient-days; p = 0.048] was observed during the intervention period (12 monthly points), despite an increasing trend in incidence of extended-spectrum beta-lactamase-producing Enterobacteriaceae (ESBL-PE) isolates (0.02/1,000 patient-days per month; p = 0.093). As expected, vancomycin consumption was unaffected by the intervention. A total of 337 prescriptions were reviewed in the intervention period; most were microbiologically documented (81.3 %; ESBL-PE: 39.2 %). Three of four (76.6 %) carbapenems prescriptions were modified within a median [interquartile range] of 2 [1; 4] days, either after infectious disease physician (IDP) advice (48.4 %) or by ward physicians (28.2 %). Most changes included de-escalating (52.2 %) or reducing the planned duration (22.2 %), which resulted in a median duration of treatment of only 3 [2; 7] days. The median length of stay and mortality rate were not influenced by the intervention. This reasonably practicable antimicrobial stewardship program including controlled delivery and systematic reevaluation of carbapenems prescriptions was able to reduce their use in our hospital, despite a rising ESBL-PE incidence.