Does Height of Fever Influence the Probability of Serious Bacterial Infections in Febrile Children?

Objective

Fever represents 10% to 25% of pediatric emergency department (ED) visits in young children. Most children presenting to ED with febrile illness are self-limited viral infections. On the other hand, Serious Bacterial Infection (SBI) rates are low. They are estimated to occur between 6% of infants younger than 3 months and 5% to 7% of children between 3 and 36 months of age. Although it is challenging to differentiate between viral and bacterial infections based on the degree of fever, historically, high fever has been associated with increased incidence of SBI. Fever may be the only presenting finding, as symptoms may be subtle, and early infections may not be clinically apparent. Therefore, there is considerable variability in evaluation, treatment, and overall resource utilization in managing febrile children presenting to ED. This study aims to determine whether the height or duration of fever can predict the likelihood of SBI in children.

Methods

We performed a retrospective review of febrile children (3-36 months old) who presented to the Pediatric ED between January 2017 and December 2021. Children 3-36 months of age presenting to ED with a documented temperature of 102.2 0F (39 0C) or more were included. Older age groups and/or critically ill children requiring resuscitation were excluded. Clinical characteristics, such as temperature at admission, fever duration, admission diagnosis, and associated symptoms, were analyzed. Serious Bacterial Infection (SBI) was defined as Pneumonia, Urinary Tract Infection (UTI), Meningitis, or Sepsis/Bacteremia. Data was tabulated as number, frequency, median, and range.

Result

We reviewed 444 febrile children, including 36 (8%) with SBI and 408 (92%) without SBI. The mean temperature at admission of children with an SBI was significantly higher than those without SBI (mean Temp 103.0°F±1.6 vs. 102.1°F±1.3, p<0.001) and 64% did have an admitting temperature ≥102.20F (p=0.022). There was a significant difference in SBI versus non-SBI group in fever duration (2.5±1.6 vs. 1.6±1.1 days, p<0.001), WBC count (14.2±7.7 vs. 10.4±3.9, p<0.001), Procalcitonin level (2.2±3.1 vs 0.8±1.7, p=0.020) and immunization status (58.3% vs 70.3%, p<0.018). The SBI was 64% pneumonia and 36% UTI. Both groups had associated symptoms (cough, rhinorrhea, vomiting/diarrhea) at presentation to the ED (SBI, 86.1% vs. non-SBI, 85.8%, p=0.95).

Conclusion

The rate of SBI was 8% in our patient population, and it was associated with a longer fever duration. Although the mean temperature was slightly higher in the SBI group than in the non-SBI group, it was not strongly associated with an SBI. Thus, a single parameter, such as the degree of fever alone, cannot be used to stratify the risk of febrile children. Height and duration of fever, along with increased WBC count, could indicate the severity of illness and call for further investigation.