Risk of Serious Bacterial Infection in Infants Aged ≤60 Days Presenting to Emergency Departments with a History of Fever Only

Objective To compare the risk of serious bacterial infection between infants aged 60 days who are febrile in the emergency department (ED) and those who have only a history of fever and are afebrile on arrival to the ED. Study design In this secondary analysis of a multicenter prospective study using data collected between December 2008 and May 2013, we compared the rate of serious bacterial infection (urinary tract infection [UTI], bacteremia, and/or bacterial meningitis) between infants who have a history of fever but are afebrile on arrival to the ED and those with fever documented in the ED (rectal temperature >= 38.0 degrees C) using relative risk (RR) with 95% CI. Stratified analyses were performed for age (<= 28 and 29-60 days) and serious bacterial infection type. Infants born prematurely and those with a clinical focal infection or serious illness were excluded. Results A total of 3825 infants (mean age, 35.2 days; 56.9% male) were included. Of the 1233 (32.2%) who were afebrile in the ED, 108 (8.8%) had a serious bacterial infection (UTI, n = 94 [7.6%]; bacteremia, n = 19 [1.5%]; bacterial meningitis. n = 8 [0.6%]). Of the 2592 infants (67.8%) who were febrile in the ED, 331 (12.8%) had a serious bacterial infection (UTI, n = 285 [11.0%]; bacteremia, n = 61 [2.4%]; bacterial meningitis, n = 17 [0.7%)). The RR for serious bacterial infection for afebrile vs febrile infants was 0.68 (95% CI, 0.56-0.84). A lower risk of serious bacterial infection was also seen among afebrile vs febrile infants aged <= 28 days (RR, 0.69; 95% CI, 0.52-0.93) and age 29-60 days (RR, 0.67; 95% CI, 0.50-0.89). Conclusions The prevalence of serious bacterial infection is lower in infants aged days with a history of fever compared with those who are febrile on arrival to the ED. The small risk reduction in this group is unlikely to alter decision making.