Validity of the Use of Wrist and Forehead Temperatures in Screening the General Population for COVID-19: A Prospective Real-World Study

Background: we aimed to compare the accuracy of individuals’ wrist and forehead temperatures with their tympanic temperature under different circumstances. methods: we performed a prospective observational study in a real-life population in ningbo first hospital in china. we consecutively recorded individuals’ wrist and forehead temperatures in celsius (°c) using a non-contact infrared thermometer (ncit). we also measured individuals’ tympanic temperature using a tympanic thermometer (irtt) and defined fever as a tympanic temperature of ≥37.3 °c. results: we enrolled 528 participants, including 261 indoor and 267 outdoor participants. we grouped the outdoor participants into four groups according to their means of transportation to the hospital: by foot, by bicycle/electric vehicle, by car, or as a passenger in a car. under different circumstances, the mean difference in the forehead measurement ranged from -1.72 to -0.56 °c across groups, and that in the wrist measurement ranged from -0.96 to -0.61°c. both measurements had high fever screening abilities in indoor patients. (wrist: auc 0.790; 95% ci: 0.725-0.854, p<0.001; forehead: auc 0.816; 95% ci: 0.757-0.876, p <0.001). the cut-off value of the wrist measurement for detecting a tympanic temperature of ≥37.3 °c was 36.2 °c, with 86.4% sensitivity and 67.0% specificity, and the best threshold for the forehead measurement was 36.2 °c, with 93.2% sensitivity and 60.0% specificity. conclusion: wrist measurements are more stable than forehead measurements under different circumstances. both measurements have favorable fever screening abilities in indoor patients. the cut-off values were both 36.2 °c.