Non-contact infrared thermometry temperature measurement for screening fever in children

Background: During the SARS epidemic, mass fever screening at border control points and public hospitals was done by measuring forehead temperature by non- contact infrared thermometry. However, its accuracy is not well documented. Methods: We evaluated the agreement of non- contact infrared forehead temperature ( NIFT) measurement by comparing NIFT readings with tympanic temperatures taken in children ( 1 mth to 18 yrs) admitted to the general paediatric wards of Kwong Wah Hospital, Hong Kong. Results: A total of 567 patients were recruited and 1000 pairs of readings were obtained. The incidence of fever, defined as tympanic temperature ( in rectal model) > 38 degrees C ( 100.4 degrees F), was 12.3%. The mean difference between NIFT and tympanic temperature was 2.34 degrees C ( 4.21 degrees F) and the 95% limit of agreement between NIFT and tympanic temperature was 0.26 - 4.42 degrees C ( 0.47 - 7.96 degrees F). NIFT was significantly lower than tympanic temperature readings. The optimal cut- off point of NIFT derived from the receiver- operator characteristics curve for fever definition was 35.1 degrees C ( 95.2 degrees F). The sensitivity, specificity, positive predictive value and negative predictive value of this cut- off point for fever screening were 89.4%, 75.4%, 33.7% and 98.1%, respectively. Conclusions: NIFT measurement has a reasonable accuracy in detecting tympanic fever in children. However, one should be aware of the high false- positive rate of fever screening using NIFT.