Table 3

Multivariable Cox Proportional Hazards Models


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)

APS – modified acute physiology score

NS – not significant (p > 0.05)

-- Not included in final model

Time at risk is the time from hospital admission to index culture collection

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%.

Thom et al. BMC Infectious Diseases 2008 8:116   doi:10.1186/1471-2334-8-116