title: Stratification of the impact of inappropriate empirical antimicrobial therapy for Gram-negative bloodstream infections by predicted prognosis.
abstract: The bloodstream infection mortality risk score (BSIMRS) predicts the outcome of patients with Gram-negative bloodstream infections (BSI) with high discrimination. This retrospective cohort study examined the impact of inappropriate antimicrobial therapy on mortality in adult patients with Gram-negative BSI admitted to Palmetto Health Hospitals in Columbia, SC, USA, from 1 January 2011 to 31 December 2012 after stratification by predicted prognosis at initial presentation using BSIMRS. A multivariate Cox regression model was used to identify independent risk factors for 28-day mortality overall and within each predefined BSIMRS category (<5, 5 to 9, and ≥ 10). Relative risk reduction (RRR), absolute risk reduction (ARR), and number needed to treat (NNT) were calculated from a predictive logistic regression model of mortality. Overall, 390 unique patients with first episodes of Gram-negative BSI were identified. The median age was 66 years, and 229 (59%) were women. There was significant association between inappropriate antimicrobial therapy and mortality in patients with BSIMRS of 5 to 9 (adjusted hazard ratio [aHR], 3.55; 95% confidence intervals [CI], 1.22 to 8.31; P = 0.02) and BSIMRS of ≥ 10 (aHR, 4.99; 95% CI, 1.09 to 22.87; P = 0.04) but not in those with BSIMRS of <5 (aHR, 3.34; 95% CI, 0.17 to 22.77; P = 0.34). RRR, ARR, and NNT were 0.25, 0.02, and 63 for BSIMRS of <5; 0.56, 0.32, and 3 for BSIMRS of 5 to 9; and 0.39, 0.39, and 3 for BSIMRS of ≥ 10, respectively. There is a significant benefit from appropriate antimicrobial therapy in patients with Gram-negative BSI with guarded (BSIMRS of 5 to 9) and poor (BSIMRS of ≥ 10) predicted prognosis. Survival difference remains unclear among those with good predicted prognosis (BSIMRS of <5) at initial presentation.
authors.affiliation: University of South Carolina School of Medicine, Columbia, South Carolina, USA.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Cain
authors.affiliation: Department of Clinical Pharmacy, Palmetto Health Richland, Columbia, South Carolina, USA.
authors.forename: Joseph
authors.initials: J
authors.lastname: Kohn
authors.affiliation: Department of Clinical Pharmacy and Outcomes Science, South Carolina College of Pharmacy, University of South Carolina, Columbia, South Carolina, USA.
authors.forename: P Brandon
authors.initials: PB
authors.lastname: Bookstaver
authors.affiliation: Department of Medicine, Division of Infectious Diseases, University of South Carolina School of Medicine, Columbia, South Carolina, USA.
authors.forename: Helmut
authors.initials: H
authors.lastname: Albrecht
authors.affiliation: Department of Medicine, Division of Infectious Diseases, University of South Carolina School of Medicine, Columbia, South Carolina, USA majdi.alhasan@uscmed.sc.edu.
authors.forename: Majdi N
authors.initials: MN
authors.lastname: Al-Hasan
mesh_terms: D000368:Aged; D000900:Anti-Bacterial Agents / Q000627:therapeutic use*; D016470:Bacteremia / Q000188:drug therapy* / Q000401:mortality; D015331:Cohort Studies; D005260:Female; D016905:Gram-Negative Bacterial Infections / Q000097:blood / Q000188:drug therapy* / Q000401:mortality*; D006801:Humans; D057970:Inappropriate Prescribing / Q000706:statistics & numerical data*; D053208:Kaplan-Meier Estimate; D008297:Male; D008875:Middle Aged; D011379:Prognosis; D016016:Proportional Hazards Models; D012189:Retrospective Studies; D013022:South Carolina / Q000453:epidemiology; D016896:Treatment Outcome
chemical_list: D000900:Anti-Bacterial Agents