Myth #5: If the fever doesn’t come down, the cause muse be serious…
What happens if the fever doesn’t come down to normal? Does that mean the cause is more serious than if it does? This is part 5 of a 10-part series where I will be busting what I consider to be the top 10 myths involving pediatric fever.
Bonadio WA, et al., 19931
This 1993 study published in clinical pediatrics involved 140 children age 2-24 months with different severities of illnesses including bacterial meningitis, bacteremia and viral syndromes. They set out to determine if changes in temperature after Tylenol administration at 60-90 minutes predicted disease severity. They found no difference in fever reduction between the different disease etiologies. More importantly, it was uncommon that any of the patients achieved complete resolution of their fever, regardless of severity of the disease. Interestingly though, they found that age is more predictive of determining the amount of fever decrease and postulated a formula to predict degree of expected fever reduction. Not really sure this formula has any real usefulness in clinical practice…but it’s still pretty cool.
Degree (C) of defervescence = 1.66 – (0.028 X age in months)
Weisse ME, et al., 19872
A similar study from 1987 published in pediatric infectious disease journal took 100 children age 9 days – 17 years with a fever>102° F. The children were split up into two groups. Either having a bacterial or viral cause of their fever. They were given Tylenol at 15 mg/kg and their fever was measured after 1 hour. Investigators found no difference in fever reduction between viral or bacterial infections. On a side note, they did find higher levels of serum white blood cells in the kids with bacterial infections. No surprise there.
Baker MD, et al., 19873
This 1987 study was the biggest of its kind. They looked at 1,559 children ages 8 weeks – 6 years of age that presented to a pediatric emergency and walk in facility. Children were diagnosed with a wide spectrum of bacterial and viral infections. They were all given Tylenol at 15 mg/kg with repeat check of their fever at 1 hour, 2 hours and by phone follow up at 5 days. Investigators found that children with cultures positive for bacterial disease or chest x-ray positive films for pneumonia had slightly GREATER one- and two-hour fever decrease compared to other diagnoses. This finding was considered statistically significant, but concluded that the fever response after Tylenol was not particularly clinically useful in identifying the cause of febrile illness in these children.
Let’s summarize the evidence…
- Fevers that don’t respond to fever medicine can be caused by viruses or bacteria.
- The rate of fever reduction just doesn’t correlate with the seriousness of the infection.
So, for our fifth myth questioning if the severity of the illness correlates with weather or not the fever comes down….I would consider this BUSTED.
References
1. Bonadio WA, et al., (1993). Correlating changes in body temperature with infectious outcome in febrile children who receive acetaminophen. Clin Pediatr (Phila),32(6):343-6. PMID 8344044.
2. Weisse ME, et al., (1987). Fever response to acetaminophen in viral vs bacterial infections. Pediatr Infect Dis J,6(12):1091-4. PMID: 3324040
3. Baker MD, et al., (1987). Childhood fever: correlation of diagnosis with temperature response to acetaminophen. Pediatrics, 80(3):315-8. PMID: 3627881
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