The Yale Observation Scale Score and the Risk of Serious Bacterial Infections in Febrile Infants.

OBJECTIVES

To assess the performance of the Yale Observation Scale (YOS) score and unstructured clinician suspicion to identify febrile infants ≤60 days of age with and without serious bacterial infections (SBIs).

METHODS

We performed a planned secondary analysis of a prospective cohort of non-critically ill, febrile, full-term infants ≤60 days of age presenting to 1 of 26 participating emergency departments in the Pediatric Emergency Care Applied Research Network. We defined SBIs as urinary tract infections, bacteremia, or bacterial meningitis, with the latter 2 considered invasive bacterial infections. Emergency department clinicians applied the YOS (range: 6-30; normal score: ≤10) and estimated the risk of SBI using unstructured clinician suspicion (<1%, 1%-5%, 6%-10%, 11%-50%, or >50%).

RESULTS

Of the 4591 eligible infants, 444 (9.7%) had SBIs and 97 (2.1%) had invasive bacterial infections. Of the 4058 infants with YOS scores of ≤10, 388 (9.6%) had SBIs (sensitivity: 51/439 [11.6%]; 95% confidence interval [CI]: 8.8%-15.0%; negative predictive value: 3670/4058 [90.4%]; 95% CI: 89.5%-91.3%) and 72 (1.8%) had invasive bacterial infections (sensitivity 23/95 [24.2%], 95% CI: 16.0%-34.1%; negative predictive value: 3983/4055 [98.2%], 95% CI: 97.8%-98.6%). Of the infants with clinician suspicion of <1%, 106 had SBIs (6.4%) and 16 (1.0%) had invasive bacterial infections.

CONCLUSIONS

In this large prospective cohort of febrile infants ≤60 days of age, neither the YOS score nor unstructured clinician suspicion reliably identified those with invasive bacterial infections. More accurate clinical and laboratory predictors are needed to risk stratify febrile infants.