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Refined Lab-score, a Risk Score Predicting Serious Bacterial Infection in Febrile Children Less Than 3 Years of Age

Leroy, Sandrine, MD, PhD*,†,‡; Bressan, Silvia, MD, PhD§; Lacroix, Laurence, MD; Andreola, Barbara, MD§; Zamora, Samuel, MD; Bailey, Benoit, MD; Da Dalt, Liviana, MD§; Manzano, Sergio, MD; Gervaix, Alain, MD; Galetto-Lacour, Annick, MD

The Pediatric Infectious Disease Journal: May 2018 - Volume 37 - Issue 5 - p 387–393
doi: 10.1097/INF.0000000000001915
Original Studies

Background: The identification of serious bacterial infection (SBI) in children with fever without source remains a challenge. A risk score called Lab-score, based on C-reactive protein, procalcitonin and urinary dipstick results was derived to predict SBI. However, all biomarkers were initially dichotomized, leading to weak statistical reliability and lack of transportability across diverse settings. We aimed to refine and validate this risk-score algorithm.

Methods: The Lab-score was refined using a secondary analysis of a multicenter cohort study of children with fever without source via multilevel regression modeling. The external validation was conducted on data from a Canadian cohort study.

Results: Eight hundred seventy-seven children (24% SBI) were included for the derivation study, and 347 (16% SBI) for validation. Only C-reactive protein, procalcitonin, age and urinary dipstick remained independently associated with SBI. The model achieved an area under the receiver operating characteristic (ROC) curve of 0.94 (95% confidence interval [CI]: 0.93–0.96), which was significantly higher than any other isolated biomarker (P < 0.0001), and the original Lab-score (P < 0.0001). According to a decision curve analysis, the model yielded a better strategy than those based on independently considered biomarkers, or on the original Lab-score. The threshold analysis led to a cutoff that yielded 96% (95% CI: 92–98) sensitivity and 73% (95% CI: 70–77) specificity. The external validation found similar predictive abilities: 0.96 area under the ROC curve (95% CI: 0.93–0.99), 95% sensitivity (95% CI: 85–99) and 87% specificity (95% CI: 83–91).

Conclusion: The refined Lab-score demonstrated higher prediction ability for SBI than the original Lab-score, with promising wider applicability across settings. These results require validation in additional populations.

From the *Department of Mobile Pediatric Intensive Care Unit, Avicenne Hospital, APHP, Paris, France

EpiScience, London, United Kingdom

Unité Mixte Internationale 233, Institut de Recherche pour le Développement, INSERM U1175, and University of Montpellier, Montpellier, France

§Department of Pediatrics, University of Padova, Italy

Division of Pediatric Emergency Medicine, Geneva University Hospitals, Geneva, Switzerland

Division of Emergency Medicine, Department of Pediatrics, CHU Sainte-Justine, Université de Montréal, Montréal, Quebec, Canada.

Accepted for publication December 11, 2017.

The authors have no funding or conflicts of interest to disclose.

Drs. Gervaix and Galetto-Lacour contributed equally.

Address for correspondence: Sandrine Leroy, MD, PhD, Institut de Recherche pour le Développement, Unité Mixte Internationale 233, INSERM U1175, Université de Montpellier, 911 Avenue Agropolis, BP 64501, F-34394 Montpellier CEDEX 5, France. E-mail:

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