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.