Multivariable Analysis

Outcome and Clinical GroupEstimated Ratio of Mean Outcomea95% Confidence Interval
Duration parenteral antibiotics
 Age ≤28 d1.651.40–1.95
 Fever ≥24 h1.120.91–1.37
 Age ≤28 d1.601.38–1.86
 Fever ≥24 h1.120.94–1.35
  • The model included all variables with a univariate association with duration of parenteral antibiotics or LOS with P <.10. Variables with P > .10 in univariate analysis (and therefore not included in the model) were: prematurity, other signs of ill appearance on initial examination (poor capillary refill or poor tone), and abnormal imaging (including renal ultrasound and/or voiding cystourethrogram).

  • a The estimated ratio of means for outcome is the exponential of the estimated difference in logs of the expected outcome variable from the generalized linear model. The estimated ratio of mean outcome in shown clinical groups is relative to the reference group (eg, ratio of mean LOS in infants ≤28 d relative to mean LOS in infants 29–60 d), similar to an odds ratio.