Point-of-care testing for procalcitonin in identifying bacterial infections in young infants: a diagnostic accuracy study

BACKGROUND: The primary objective of this study was to report on the diagnostic accuracy of point-of-care testing (POCT) for procalcitonin (PCT) in identifying invasive bacterial infections in young infants. Invasive bacterial infection was defined as the isolation of a bacterial pathogen in blood or cerebrospinal fluid culture. METHODS: This was a prospective observational diagnostic accuracy study. Young infants less than 90 days of age presenting to the Royal Belfast Hospital for Sick Children with signs of possible bacterial infection were eligible for inclusion. Eligible infants underwent point-of-care testing for procalcitonin in the emergency department. Testing was performed by clinical staff using 0.5 ml of whole blood. Results were available within 20 min. RESULTS: 126 children were included over a 5-month period between September 2017 and January 2018. There were 14 children diagnosed with bacterial infections (11.1%). Of these 4 children were diagnosed with invasive bacterial infections (3.2%). POCT procalcitonin demonstrated an excellent diagnostic accuracy for identifying children with invasive bacterial infection area under the curve (AUC) of 0.97(95% CI, 0.94 to 1.0). At a cut-off value of 1.0 ng/ml is highly accurate at identifying infants at risk of invasive bacterial infection with a sensitivity and specificity of 1.00 and 0.92 respectively. CONCLUSIONS: Point-of-care procalcitonin can be performed quickly in the emergency department and demonstrates an excellent diagnostic accuracy for the identification of young infants with invasive bacterial infections. TRIAL REGISTRATION: NCT03509727 Retrospectively registered on 26th April 2018.