Generalized Linear Mixed-Effects Model to Predict Blood Culture Testing

PredictorAdjusted Odds Ratio (95% CI)P
  29–56 d0.37 (0.23–0.60)<.001b
  57–90 d0.06 (0.04–0.10)<.001b
 Gestational agec.01b
  <37 weeks' gestation1.60 (0.94–2.72).08
  Unknown0.59 (0.36–0.96).03b
History of presenting illness
 Ear discharge2.32 (1.62–3.34)<.001b
 Tactile warmth2.29 (1.53–3.43)<.001b
 Upper respiratory infection symptomsd0.88 (0.62–1.26).50
  • a Reference group: 0 to 28 d old.

  • b Statistical significance (P < .05). In this model, age, gestational age, history of ear discharge, and history of tactile fever were independently associated with obtaining a blood culture. In the subanalysis including only the 1459 infants meeting simplified AAP diagnostic criteria (data available on request), no meaningful changes were noted, except the predictor variable <37 wk gestational age was significant (P = .04).

  • c Reference group: ≥37 wk gestation.

  • d Include cough, new nasal congestion or sneezing, rhinorrhea, wheezing, noisy breathing, and difficulty breathing.