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

Abstract

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