Threshold for defining fever varies with age, especially in children: A multi-site diagnostic accuracy study.
Rajesh Kasbekar, Aftab Naz, Lorenzo Marcos and 4 others
PMID 33735515WHAT IT FOUND
Age-based fever thresholds on ear thermometers identified illness far more accurately than the standard fixed 38°C rectal threshold.
The ear device matched clinical diagnoses in 93.5% of neonates, compared to 72.8% for rectal thermometers using fixed cutoffs.
Key findings
01An ear thermometer using age-based thresholds achieved 93.5% accuracy in predicting illness in neonates, compared to 72.8% accuracy for a rectal thermometer using fixed thresholds.
02In the overall population, the age-based ear thermometer met acceptance criteria for sensitivity and specificity, while fixed-threshold rectal thermometers showed much lower sensitivity.
03Agreement between the ear thermometer and reference rectal/ear thermometers was strong, with an average bias of -0.02°C.
STILL TO COME
How it was doneWhat they foundWhat it means for RNs
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What it does not show
The study did not account for time of day or sex, which can influence normal body temperature. Clinical diagnosis of "ill" vs "well" was based on healthcare professional impressions, which can vary between sites and physicians. The study used specific commercial devices; results may not generalize to all infrared or rectal thermometers. The manufacturer of the test device (Kaz USA, Inc., a Helen of Troy Company) performed the analysis and manuscript preparation, introducing potential conflict of interest.
Declared interests
The study was implemented and data collected by third-party independent investigators with no financial interest. However, the analysis and manuscript preparation were conducted by Kaz USA, Inc., a Helen of Troy Company, which is the manufacturer of the test device (ThermoScan Braun IRT6520).
The easy way to misread this
Do not interpret the high accuracy of the age-based ear thermometer as evidence that it replaces a comprehensive clinical assessment. The authors emphasize that fever is only one marker of illness, and clinical impression based on history and physical examination remains the gold standard for diagnosis and management.