Slight Variation in Body Temperature Linked to Mortality Risk

Individuals body temperature measures show meaningful variation, and only a slight increase in temperature was associated with an increased risk for mortality within 1 year, according to the findings of a recent study.

The observational study included 35,488 patients who presented at a large academic clinic with a normal temperature and who had not received a diagnosis for an infection (mean age 52.9 years, 64% women, 41% non-white race). The mean temperature was 36.6°C (97.9°F; 95% range 35.7-37.3°C).
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Overall, the researchers found that several demographic factors, including body mass index, were associated with individual temperatures. Lower temperatures were associated with older age and various comorbidities, including hyperthyroidism. Additionally, African American women had higher temperatures compared with white men. Higher temperatures were also associated with comorbidities, including cancer.

While measured factors collectively explained only 8.2% of individual temperature variation, the unexplained variation was a significant predictor of subsequent mortality after the researchers controlled for all measured factors. For instances, an increase of 0.149°C was associated with an 8.4% higher risk for 1-year mortality.

“Individuals’ baseline temperatures showed meaningful variation that was not due solely to measurement error or environmental factors,” the researchers concluded. “Baseline temperatures correlated with demographics, comorbid conditions, and physiology, but these factors explained only a small part of individual temperature variation. Unexplained variation in baseline temperature, however, strongly predicted mortality.”

—Melissa Weiss

Reference:

Obermeyer Z, Samra JK, Mullainathan S. Individual differences in normal body temperature: longitudinal big data analysis of patient records [published online December 13, 2017. BMJ. https://doi.org/10.1136/bmj.j5468.