Validation of the Feverkidstool and procalcitonin for detecting serious bacterial infections in febrile children

Background: To validate the Feverkidstool, a prediction model consisting of clinical signs and symptoms and C-reactive protein (CRP) to identify serious bacterial infections (SBIs) in febrile children, and to determine the incremental diagnostic value of procalcitonin.
Methods: This prospective observational study that was carried out at two Dutch emergency departments included children with fever, aged 1 month to 16 years. The prediction models were developed with polytomous logistic regression differentiating "pneumonia" and "other SBIs" from "non-SBIs" using standardized, routinely collected data on clinical signs and symptoms, CRP, and procalcitonin.
Results: A total of 1,085 children were included with a median age of 1.6 years (interquartile range 0.8-3.4); 73 children (7%) had pneumonia and 98 children (9%) had other SBIs. The Feverkidstool showed good discriminative ability in this new population. After adding procalcitonin to the Feverkidstool, c-statistic for "pneumonia" increased from 0.85 (95% confidence interval (CI) 0.76-0.94) to 0.86 (0.77-0.94) and for "other SBI" from 0.81 (0.73-0.90) to 0.83 (0.75- 0.91). A model with clinical features and procalcitonin performed similar to the Feverkidstool.
Conclusion: This study confirms the external validity of the Feverkidstool, with CRP and procalcitonin being equally valuable for predicting SBI in our population of febrile children. Our findings do not support routine dual use of CRP and procalcitonin.