A quasi-experimental study of a bundled diagnostic stewardship intervention for ventilator-associated pneumonia.

Objectives: Diagnostic error in the use of respiratory cultures for ventilator-associated pneumonia (VAP) fuels misdiagnosis and antibiotic overuse within intensive care units. In this prospective quasi-experimental study (NCT05176353), we aimed to evaluate the safety, feasibility, and efficacy of a novel VAP-specific bundled diagnostic stewardship intervention (VAP-DSI) to mitigate VAP over-diagnosis/overtreatment.

Methods: We developed and implemented a VAP-DSI using an interruptive clinical decision support tool and modifications to clinical laboratory workflows. Interventions included gatekeeping access to respiratory culture ordering, preferential use of non-bronchoscopic bronchoalveolar lavage for culture collection, and suppression of culture results for samples with minimal alveolar neutrophilia. Rates of adverse safety outcomes, positive respiratory cultures, and antimicrobial utilization were compared between mechanically ventilated patients (MVPs) in the 1-year post-intervention study cohort (2022-2023) and 5-year pre-intervention MVP controls (2017-2022).

Results: VAP-DSI implementation did not associate with increases in adverse safety outcomes but did associate with a 20% rate reduction in positive respiratory cultures per 1000 MVP days (pre-intervention rate 127 [95% CI: 122-131], post-intervention rate 102 [95% CI: 92-112], p < 0.01). Significant reductions in broad-spectrum antibiotic days of therapy per 1000 MVP days were noted after VAP-DSI implementation (pre-intervention rate 1199 [95% CI: 1177-1205], post-intervention rate 1149 [95% CI: 1116-1184], p 0.03).

Discussion: Implementation of a VAP-DSI was safe and associated with significant reductions in rates of positive respiratory cultures and broad-spectrum antimicrobial use. This innovative trial of a VAP-DSI represents a novel avenue for intensive care unit antimicrobial stewardship. Multicentre trials of VAP-DSIs are warranted.