Abstract
BACKGROUND: Ageing affects immunity, potentially altering fever response to infection. We assess effects of biological variables on basal temperature, and during COVID-19 infection, proposing an updated temperature threshold for older adults ≥65 years.
METHODS: Participants were from four cohorts: 1089 unaffected adult TwinsUK volunteers; 520 adults with emergency admission to a London hospital with RT-PCR confirmed SARS-CoV-2 infection; 757 adults with emergency admission to a Birmingham hospital with RT-PCR confirmed SARS-CoV-2 infection and 3972 adult community-based COVID Symptom Study participants self-reporting a positive RT-PCR test. Heritability was assessed using saturated and univariate ACE models; mixed-effect and multivariable linear regression examined associations between temperature, age, sex and BMI; multivariable logistic regression examined associations between fever (≥37.8°C) and age; receiver operating characteristic (ROC) analysis was used to identify temperature threshold for adults ≥ 65 years.
RESULTS: Among unaffected volunteers, lower BMI (p=0.001), and increasing age (p<0.001) associated with lower basal temperature. Basal temperature showed a heritability of 47% 95% Confidence Interval 18-57%). In COVID-19+ participants, increasing age was associated with lower temperatures in Birmingham and community-based cohorts (p<0.001). For each additional year of age, participants were 1% less likely to demonstrate a fever ≥37.8°C (OR 0.99; p<0.001). Combining healthy and COVID-19+ participants, a temperature of 37.4°C in adults ≥65 years had similar sensitivity and specificity to 37.8°C in adults <65 years for discriminating infection.
CONCLUSIONS: Ageing affects temperature in health and acute infection, with significant heritability, indicating genetic factors contribute to temperature regulation. Our observations suggest a lower threshold (37.4°C/97.3°F) for identifying fever in older adults ≥65 years.
Original language | English |
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Article number | glab295 |
Journal | The journals of gerontology. Series A, Biological sciences and medical sciences |
Early online date | 5 Oct 2021 |
DOIs | |
Publication status | E-pub ahead of print - 5 Oct 2021 |
Bibliographical note
© The Author(s) 2021. Published by Oxford University Press on behalf of The Gerontological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.Keywords
- COVID-19
- Fever
- Immunesenescence
- Infection
- Thermoregulation