Quantifying the Importance of Active Antimicrobial Therapy among Patients with Gram-negative Bloodstream Infections: Cefepime as a Representative Agent.

The quantitative importance of active antibiotic treatment relative to other modifiable and non-modifiable risk factors for mortality has not been well defined in the literature. Here we quantify the impact of active antibiotic treatment on mortality relative to other disease modifiers in patients with Gram-negative bacteremia. Patients with at least one positive blood culture who were treated with ≥24 hours of cefepime for GNBSI were included for study. To examine in-hospital survival, a full primary model and a base model with the least significant covariate from the primary model were established. Relative importance of covariates was calculated using percentages of difference in log likelihood values when each covariate was iteratively added to the base model. A total of 154 unique patients with Gram-negative bloodstream infections (GNBSI) were included. The primary model included active cefepime therapy (p=0.004), normalized days to positive culture (p=0.091), ICU at time of treatment (p=0.001), modified APACHE II score on day zero (p=0.025), history of leukemia (p=0.008), and prior immunosuppressive therapy (p=0.088). Active antimicrobial therapy displayed a relative importance at 32.2%, which was second to ICU residence at the time of culture. Amongst all covariates in our model, active antimicrobial therapy was the only modifiable variable and contributed significantly to in-hospital survival in acutely ill patients with GNBSI.