Predictive factors for 30-day mortality after polymyxin B treatment of carbapenem-resistant Gram-negative bacilli infections

Abstract

Objectives

This study aimed to investigate the associated factors predicting 30-day mortality of carbapenem-resistant Gram-negative bacilli (CR-GNB) infections, with focus on polymyxin B AUC_{ss,24 h}/MIC.

Methods

This prospective cohort study included patients with CR-GNB infections from January 2022 to January 2024. The primary outcome was 30-day mortality. Classification and regression tree (CART) analysis was used to calculate the AUC_{ss,24 h}/MIC threshold for 30-day mortality. Multivariate analysis was conducted to assess risk factors affecting this outcome.

Results

We enrolled 107 patients, among which 30-day mortality occurred in 31 (29.0%) cases. The CART-derived AUC_{ss,24 h}/MIC breakpoint was 51.3, and patients in the below-breakpoint group had 3.4-fold higher 30-day mortality than those in the above-breakpoint group (58.1% vs 17.1%, P < 0.001). On multivariate analysis, polymyxin B AUC_{ss,24 h}/MIC of ≥51.3 (aOR 0.08, P = 0.001) predicted a lower risk for 30-day mortality. In subgroup analysis, the survival benefit of AUC_{ss,24 h}/MIC target attainment remained in patients with high risk of mortality or carbapenem-resistant Acinetobacter baumannii infections.

Conclusions

Polymyxin B AUC_{ss,24 h}/MIC of ≥51.3 independently predicted lower 30-day mortality in treating CR-GNB infections. Further studies should verify the AUC_{ss,24 h}/MIC target associated with survival outcomes in larger randomized controlled trials.