Outcome of Inappropriate Empirical Antibiotic Therapy in Patients With Staphylococcus Aureus Bacteraemia: Analytical Strategy Using Propensity Scores

Clin Microbiol Infect. 2006 Jan;12(1):13-21. doi: 10.1111/j.1469-0691.2005.01294.x.

Abstract

Patients with Staphylococcus aureus bacteraemia (SAB) who received either inappropriate or appropriate empirical therapy were compared by using two risk stratification models: (1) a cohort study using a propensity score to adjust for confounding by empirical treatment assignment; and (2) a propensity-matched case-control study. Inappropriate empirical therapy was modelled on the basis of patient characteristics, and included in the multivariate model to adjust for confounding. For case-matching analysis, patients with inappropriate empirical therapy (cases) were matched to those with appropriate empirical therapy (controls) on the basis of the propensity score (within 0.03 on a scale of 0-1). In total, 238 patients with SAB were enrolled in the cohort study. Characteristics associated with inappropriate empirical therapy were methicillin resistance, underlying haematological malignancy, no history of colonisation with methicillin-resistant S. aureus, and a long hospital stay before SAB. These variables were included in the propensity score, which had an area under the receiver operating characteristics curve of 85%. In the cohort study, SAB-related mortality was 39% (45/117) for inappropriate empirical therapy vs. 28% (34/121) for appropriate empirical therapy (odds ratio (OR) 1.60; 95% CI 0.93-2.76). After adjustment for independent predictors for mortality and the propensity score, inappropriate empirical therapy was not associated with mortality (adjusted OR 1.39; 95% CI 0.62-3.15). In the matched case-control study (50 pairs), SAB-related mortality was 32% (16/50) for inappropriate empirical therapy and 28% (14/50) for appropriate empirical therapy (McNemar's test; p 0.85; OR 1.15; 95% CI 0.51-2.64). In conclusion, inappropriate empirical therapy resulted in only a slight tendency towards increased mortality in patients with SAB.

Publication types

  • Comparative Study

MeSH terms

  • Aged
  • Anti-Bacterial Agents / pharmacology
  • Anti-Bacterial Agents / therapeutic use*
  • Bacteremia / drug therapy*
  • Bacteremia / microbiology
  • Bacteremia / mortality*
  • Bias
  • Case-Control Studies
  • Cohort Studies
  • Female
  • Humans
  • Logistic Models
  • Male
  • Medication Errors*
  • Middle Aged
  • Multivariate Analysis
  • Staphylococcal Infections / drug therapy
  • Staphylococcal Infections / microbiology
  • Staphylococcal Infections / mortality
  • Staphylococcus aureus / drug effects*
  • Treatment Outcome

Substances

  • Anti-Bacterial Agents