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Table 3 Multivariable Cox Proportional Hazards Models

From: Impact of Empiric Antimicrobial Therapy on Outcomes in Patients with Escherichia coli and Klebsiella pneumoniae Bacteremia: A Cohort Study

  Outcome = In-hospital Mortality Outcome = Length of Stay
Variable Hazard Ratio (95% CI) Hazard Ratio (95% CI)
All Bacteremias (N = 416)   
Appropriate Antibiotics -8 to 24 hours 1.03 (0.60 to 1.78) 1.11 (0.86 to 1.44)
Age (per year) 1.02 (1.01 to 1.04) NS
Male Sex -- NS
Central line at time of culture -- 0.67 (0.54 to 0.85)
Time at risk (per day) NS 0.66 (0.52 to 0.83)
APS 24 hours before culture 1.06 (1.05 to 1.08) 0.99 (0.97 to 0.99)
Polymicrobial bacteremia NS --
E. coli Bacteremia (N = 225)   
Appropriate Antibiotics -8 to 24 hours 1.11 (0.52 to 2.34) 1.04 (0.72 to 1.51)
Central line at time of culture NS NS
Time at risk NS 0.66 (0.47 to 0.91)
APS 24 hours before culture 1.06 (1.04 to 1.08) 0.98 (0.97 to 1.00)
Polymicrobial bacteremia NS --
Klebsiella Bacteremia (N = 203)   
Appropriate Antibiotics -8 to 24 hours 0.84 (0.42 to 1.70) 1.21 (0.84 to 1.73)
Age 1.03 (1.01 to 1.06) --
Time at risk -- 0.65 (0.47 to 0.90)
Central line at time of culture -- 0.62 (0.44 to 0.86)
APS 24 hours before culture 1.06 (1.03 to 1.09) 0.98 (0.97 to 1.00)
  1. APS – modified acute physiology score
  2. NS – not significant (p > 0.05)
  3. -- Not included in final model
  4. Time at risk is the time from hospital admission to index culture collection
  5. NB: Hazard Ratios are reported per one unit increase in the study variable; for example a HR of 1.06 for APS can be interpreted as a 6% increase in the hazard of death for each one unit increase in APS; therefore for an increase in APS of 5 points the hazard of death would increase by 30%.