Algorithm accurately identifies babies at low risk of IBI

The so-called “Step-by-Step” algorithm, a sequential approach to identifying young febrile infants at low risk for invasive bacterial infection (IBI) on the basis of clinical and laboratory parameters, is more accurate than the classic Rochester criteria or the more recently developed “Lab-score,” a new study shows.

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Investigators collected data for 2185 infants aged 90 days or younger with fever without a source brought to 11 European pediatric emergency departments. They then applied the Step-by-Step algorithm to the study sample to analyze its accuracy. This approach evaluates sequentially the general appearance of the infant, his or her age, results of the urinalysis, and results of tests for blood biomarkers, including procalcitonin, C-reactive protein (CRP), and absolute neutrophil count. Investigators also applied the Rochester criteria and the Lab-score to study participants’ data and compared the diagnostic performances of the 3 guidelines.                               

Of total participants, 87 (4%) were diagnosed with an IBI (meningitis, bacteremia or septic arthritis), 80 of whom were identified as at high or intermediate risk using the Step-by-Step protocol. Sensitivity and negative predictive value for ruling out an IBI were 92.0% and 99.3%, respectively, for Step-by-Step; 81.6% and 98.3% for the Rochester criteria; and 59.8% and 98.1% for the Lab-score. Step-by-Step misclassified 7 infants with an IBI compared with 16 by Rochester criteria and 35 by the Lab-score. Six of 7 missed patients had fever duration of less than 2 hours at presentation (Gomez B, et al. Pediatrics. 2016;138[2]:e20154381).

Commentary

This age-old pediatric struggle continues: deciding which young babies with fever have serious bacterial infections while being judicious in use of invasive diagnostic studies, hospitalization, and treatment. The updated approach described here incorporates newer laboratory technology, but no screening protocol, even this improvement on past versions, is perfect. The youngest babies (in the Step-by-Step protocol, those aged 21 days or younger) and those who appear ill are still at high risk no matter what their screening labs show. Procalcitonin offers new information, but even this rapidly responsive measure offers little help in the first hours of a febrile illness. Nonetheless, if procalcitonin and CRP are quickly available where you work, adoption of the Step-by-Step protocol may offer an improved approach to the young infant with fever without a source. -Michael G Burke, MD

Ms Freedman is a freelance medical editor and writer in New Jersey. Dr Burke, section editor for Journal Club, is chairman of the Department of Pediatrics at Saint Agnes Hospital, Baltimore, Maryland. The editors have nothing to disclose in regard to affiliations with or financial interests in any organizations that may have an interest in any part of this article.