Myth #6: If the fever is high, the cause must be serious…
Does the height of the fever predict the severity of illness? Does a child with a fever of 102° Fwarrant more of a workup than a fever of 100.4° F? How about a fever of 106° F? This is part 6 of a 10-part series where I will be busting what I consider to be the top 10 myths involving pediatric fever.
De S, et al., 20151
This study from 2015 looked at infants ages 0-5 years who presented to the Emergency Department for evaluation of sepsis. Out of the nearly 16,000 children included in the study, there were 1,120 cases of serious bacterial infections identified. However, the set point for fever evaluation in this study was only 38°C, the minimum definition of a fever. What they found was, the height of the fever did not correlate with severity of illness. Overall Sensitivity and Specificity were quite poor at 67 and 45% respectively. They realized that the younger the age of the child and duration of illness was a better predictor of Serious Bacterial Infections.
Bonadio WA, et al., 19912
How about higher temps? Well, this 1991 study published in clinical pediatrics looked at 683 febrile infants ages 4-8 weeks receiving outpatient evaluation for sepsis and set to determine if the height of the fever predicted severity of the disease. The definition for hyperpyrexia in this study was a fever greater than 40°C. Out of the 683 infants in the study, only 34 cases of serious bacterial infections were identified. Only 4% of all infants had fevers > 40°C, and of those, only 25% had a serious bacterial infection. 75% had everyday viral syndromes. The Sensitivity was quite low at 21%, but fairly Specific at 97%.
Trautner BW, et al., 20063
But what about REALLLLY high fevers. Well, here is a prospective study from 2006 of 103 febrile children with a fever > 106°F(that’s 41.1°C). 20 kids were identified as having a serious bacterial infection and 22 kids had lab confirmed viral syndromes. Investigators concluded that children with fevers > 106 had equal risk of a serious bacterial infection vs a simple viral illness
Let’s summarize the evidence…
- If the fever is high, the cause may or may not be serious.
- If the child looks sick, the cause is more likely to be serious.
- How the child looks is what is important, not the exact level of fever.
So, for our sixth myth questioning if the height of fever correlates with the severity of illness…I would consider this BUSTED.
References
- De S, et al., (2015). Lack of Accuracy of Body Temperature for Detecting Serious Bacterial infection in Febrile Episodes. Pediatr Infect Dis J, 34(9):940-4. DOI: 10.1097/INF.0000000000000771
- Bonadio WA, et al., (1991). Relationship of fever magnitude to rate of serious bacterial infections in infants aged 4-8 weeks. Clin Pediatr (Phila). 30(8):478-80. PMID: 1914347
- Trautner BW, et al., (2006). Prospective evaluation of the risk of serious bacterial infection in children who present to the emergency department with hyperpyrexia (temperature of 106 degrees F or higher). Pediatrics, 118(1):34-40. DOI: 10.1542/peds.2005-28
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