Field testing the utility of procalcitonin and the acute infantile observation score in febrile infants 6 to 36 months old presenting to the pediatric emergency department with no obvious focus of infection

Clin Pediatr (Phila). 2013 Jun;52(6):503-6. doi: 10.1177/0009922813483873. Epub 2013 Apr 22.


Background: Serious bacterial illness (SBI) presents a diagnostic challenge in febrile infants. History, clinical signs, and laboratory information combined with experiential knowledge affects decisions to admit and treat.

Aim: To assess the utility of serum procalcitonin and the Acute Infantile Observation Score (AIOS) performed at emergency department presentation in predicting (a) confirmed serious bacterial illness and (b) illness severity.

Methods: Sensitivity, specificity, and likelihood ratios were calculated for C-reactive protein, white cell count, serum procalcitonin, and AIOS.

Results: Forty-six infants were recruited. Seven had a diagnosis of SBI, 28 were moderately ill with length of stay >24 hours, and 12 were severely ill with length of stay >96 hours. The positive likelihood ratios for confirmed SBI were C-reactive protein = 5.3, procalcitonin = 0.43, white cell count = 1.9, and AIOS = 1.5.

Conclusion: Procalcitonin and the AIOS do not modify the diagnostic uncertainty of the ED physician assessing the febrile infant with respect to admission or antibiotic treatment above standard laboratory investigations.

Keywords: AIOS; emergency department; procalcitonin; serious bacterial Iilness.

MeSH terms

  • Acute Disease
  • C-Reactive Protein / metabolism
  • Calcitonin / blood*
  • Calcitonin Gene-Related Peptide
  • Child, Preschool
  • Female
  • Fever of Unknown Origin / blood*
  • Humans
  • Infant
  • Infections / blood*
  • Lymphocyte Count
  • Male
  • Predictive Value of Tests
  • Protein Precursors / blood*
  • Sensitivity and Specificity
  • Severity of Illness Index*


  • CALCA protein, human
  • Protein Precursors
  • Calcitonin
  • C-Reactive Protein
  • Calcitonin Gene-Related Peptide