Study on the value and optimal cut-off value of infrared forehead therm ometer for fever screening in the fever clinic

Objective To evaluate the value and the optimal cut-off value of infrared forehead thermometer for fever screening. Methods Body temperatures of 1 176 patients who visited the fever clinic from June 1 st to August 30 th 2018 were measured using both infrared forehead thermometer and mercury thermometer. Results Among 1 176 patients, 529(45%) were males and 647(55%) were females, with the mean age of 36.91±16.46 years old. Bland-Altman results showed that the consistency of frontal temperature and axillary temperature was relatively good. The average temperature measured by the mercury thermometer was(38.31±0.67)℃, while the average temperature measured by the infrared forehead thermometer was(37.30±0.77)℃. The mean difference was(1.01±0.64)℃. Paired t-test showed that t value was 53.774, P<0.001. The mean difference between the two types of temperatures for the normal temperature group, low fever group, moderate fever group and high fever group were(0.25±0.55),(0.83±0.50),(1.08±0.66) and(1.33±0.70)℃, respectively. The t values were 2.180, 35.721, 36.760 and 25.710, respectively, P<0.05. The sensitivity and specificity of using the infrared forehead thermometer to measure the body temperature were 0.482 and 0.913, respectively. The area under the ROC curve was 0.73, P<0.001, the 95% confidence interval was 0.650~0.811. The maximum value for the Youden index was 0.477, and the corresponding temperature was 37.05℃. Conclusion There is statistically significant difference between the body temperatures measured by the infrared forehead thermometer and the mercury thermometer, with the former lower than the latter. The higher the body temperature is, the more difference is. Since the temperature reading of infrared frontal thermometer can only be read to one decimal place in clinical practice, 37.0℃ should be used as the basis for preliminary determination of whether the patient has fever.