ABSTRACT
TOPIC: Chest Infections TYPE: Original Investigations PURPOSE: Body temperature is an important clinical marker used to screen for infections such as COVID-19. Previous studies have demonstrated individual variation in core body temperature with factors such as age, gender, circadian rhythm, menstruation, and energy expenditure;however, it is unknown whether ambient temperature affects the host ability to mount a fever. The possibility of a systematic change in body temperature during different seasons of the year has implications throughout healthcare. Using 100.4°F as the cut-off for fever regardless of ambient temperature may result in poor sensitivity in screening for infections. METHODS: We performed a retrospective chart review of patients admitted to four different hospitals for COVID-19 from 03/01/2020-02/28/2021. The 24-hour mean ambient temperature as well as the 72-hour mean ambient temperature was correlated with the percentage of patients who presented with fever. Fever was defined as maximum oral temperature greater than or equal to 100.4°F within the first 24 hours of hospitalization. Ambient temperature was stratified into deciles. Logistic regression was used to evaluate the association of ambient temperature with fever, controlling for demographics and comorbidities (congestive heart failure, pulmonary disease, hypertension, diabetes mellitus, renal disease, and liver disease). RESULTS: 5,275 patients admitted to the hospital with COVID-19 were included in the study. The mean age of patients was 61 years, 49.7% (2622) were female, and the mortality rate was 8.7%. There was a linear relationship between the ambient temperature and the sensitivity of the 100.4°F fever cut-off (i.e., the sensitivity to detect COVID-19 increased with increasing ambient temperature). In the coldest decile of ambient temperatures (<42.6°F), only 13% of COVID-19 patients presented with a fever compared to 25% in the highest decile of ambient temperature (>79.8°F). When controlling for demographics and comorbidities, the odds ratio of presenting with fever increased by 13% for every 10°F increase in ambient temperature (OR 1.13, p<0.001). CONCLUSIONS: Ambient temperature affects the sensitivity of fever in detecting COVID-19, with increased sensitivity at higher ambient temperature. The one-size-fits-all fever cut-off may not adequately detect viral infections in different locations and climates. CLINICAL IMPLICATIONS: This study shows that ambient temperature exposure should be taken into consideration when screening for infection. Lower cut-offs for fever may be required in screening patients during the winter season or in colder climates. DISCLOSURES: No relevant relationships by Sivasubramanium Bhavani, source=Admin input No relevant relationships by Neethu Edathara, source=Web Response no disclosure on file for Chad Robichaux;no disclosure on file for Philip Verhoef;