'He Had a Fever at Home': Evaluating Afebrile Infants With a History of Fever

William T. Basco, Jr, MD, MS


March 22, 2019

'He Had a Fever at Home'

The youngest babies with fever can be a downright scary situation. The mantra is that the etiology is serious until proven otherwise, as infants ≤ 60 days are a group at particularly high risk of experiencing serious bacterial infection (SBI). Physical exam is unreliable and so systematic approaches to evaluating these infants are widely used, particularly when the fever is documented upon arrival to the emergency department (ED). But what about those infants reportedly febrile at home but afebrile when they arrive in the ED? Should they be managed the same way?

A recent secondary analysis of a multicenter, prospective study of febrile infants in EDs sought to provide guidance.[1] Over 7000 infants seen at one of 26 EDs between 2008 and 2013 were screened for the initial study; data from just under 4000 of them were included in the current analysis.

Unfortunately, the original study did not collect data on whether parents had administered antipyretics before the infant was seen in the ED. Just under a third of the infants included in this analysis had a fever at home only. That left 2592 infants who had a documented fever in the ED. The mean age of the children was 35.2 days, and 56.9% were male.

Overall, the infants who were not febrile in the ED had a lower risk for SBI (8.8%) compared with infants with a documented fever (12.8%). This difference corresponded to a relative risk of 0.68 (95% confidence interval, 0.56-0.84). This finding of an overall lower risk was present in infants ≤ 28 days old as well as those > 28 days old.

The majority of the SBIs were urinary tract infections (UTIs). Compared with their febrile counterparts, the afebrile infants ≤ 28 days had a lower risk for UTI, while the afebrile infants 29-60 days old had lower risk for both UTI and bacteremia. There were eight cases of meningitis among the afebrile infants (0.6%) compared with 17 cases in the febrile infants (0.7%), a difference that was not statistically significant.

The authors concluded that, while the prevalence of SBI among infants ≤ 60 days old is lower among those who were afebrile in the ED, the difference in clinical risk was not enough to alter medical decision-making.


ED faculty during my own fellowship, now almost 25 years ago, debated this same question: What kind of workup is appropriate for an infant with only a report of fever? I find it remarkable that we have not made more progress in answering this question by now!

That said, we have certainly made significant progress in reducing the number of children who require evaluation for SBI based on vaccines, better risk data, and viral testing. And although this study shows that children with only a reported history of fever prior to ED arrival appear to be at lower risk, I fully agree with the authors that an SBI risk of 8.8% is difficult to dismiss. Even with such a large number of infants in this study population, determining differences in meningitis risk is exceedingly difficult, given that it is still a relatively rare occurrence.

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