Objective: Influenza is a highly infectious viral disease, which occurs epidemically almost every winter in Japan. Rapid screening of patients with suspected influenza in places of mass gathering is important to delay or prevent transmission of the infection. The aim of this study was to assess the effectiveness of our newly developed infection screening system that employed vital signs and percutaneous oxygen saturation (SpO2) as parameters in a clinical setting. Methods: Since SpO2 accurately reflects respiratory status during influenza virus infection, we upgraded our previous system by adding SpO2 as a new parameter to improve the screening accuracy. This system instantly measures SpO2 and vital signs (i.e., heart rate, respiration rate, and facial temperature), which automatically detects infected individuals via a neural network-based nonlinear discriminant function using these derived parameters. We tested the system on 45 patients with seasonal influenza (35.8℃ < body temperature < 40.0℃, 18-35 years) and 64 normal control subjects (35.0℃ < body temperature < 37.5℃, 18-30 years) at Japan Self-Defense Central Hospital in 2012. Results: The system identified 40/45 patients with influenza and 60/64 normal control subjects, and provided sensitivity, specificity, and positive and negative predictive value (PPV, NPV) of 88.8%, 93.8%, 90.9%, and 92.3%, respectively. By including SpO2 as a screening parameter, we achieved superior sensitivity and NPV compared to that reported in our previous paper (sensitivity = 88%; NPV = 82%). Conclusions: Our results suggest that SpO2 is a good screening parameter that improves the accuracy of infection screening. The proposed system has the potential to efficiently identify infected individuals, thereby delaying or preventing the spread of infection during epidemic seasons.
 Chou, Gao, R., Cao, B., Hu, Y., Feng, Z., Wang, D., Hu, W. and Shu, Y. (2013) Human infection with a novel avianorigin influenza A (H7N9) virus. The New England Journal of Medicine, 368, 1888-1897. doi:10.1056/NEJMoa1304459
 Wentworth, D.E., Thompson, B.L., Xu, X., Regnery, H. L., Cooley, A.J., McGregor, M.W. and Hinshaw, V.S. (1994) An influenza A (H1N1) virus, closely related to swine influenza virus, responsible for a fatal case of human influenza. Journal of Virology, 68, 2051-2058.
 Chiang, M.F., Lin, P.W., Lin, L.F., Chiou, H.Y., Chien, C. W., Chu, S.F. and Chiu, W.T. (2008) Mass screening of suspected febrile patients with remote-sensing infrared thermography: Alarm temperature and optimal distance. Journal of the Formosan Medical Association, 107, 937-944. doi:10.1016/S0929-6646(09)60017-6
 Liu, C.C., Chang, R.E. and Chang, W.C. (2004) Limitations of forehead infrared body temperature detection for fever screening for severe acute respiratory syndrome. Infection Control and Hospital Epidemiology, 25, 1109-1111. doi:10.1086/502351
 Matsui, T., Hakozaki, Y., Suzuki, S., Usui, T., Kato, T., Hasegawa, K. and Abe, S. (2010) A novel screening method for influenza patients using a newly developed noncontact screening system. Journal of Infection, 60, 271-277. doi:10.1016/j.jinf.2010.01.005
 Matsui, T., Suzuki, S., Ujikawa, K., Usui, T., Gotoh, S., Sugamata, M. and Abe, S. (2009) The development of a non-contact screening system for rapid medical inspection at a quarantine depot using a laser Doppler bloodflow meter, microwave radar and infrared thermography. Journal of Medical Engineering & Technology, 33, 481-487. doi:10.1080/03091900902952675
 Bewick, Thomas, B., Greenwood, S. and Lim, W.S. (2010) What is the role of pulse oximetry in the assessment of patients with community-acquired pneumonia in primary care? Primary Care Respiratory Journal, 19, 378-382. doi:10.4104/pcrj.2010.00049
 Sun, G., Hakozaki, Y., Abe, S., Vinh, N. Q. and Matsui, T. (2012) A novel infection screening method using a neural network and k-means clustering algorithm which can be applied for screening of unknown or unexpected infectious diseases. Journal of Infection, 65, 591-592. doi:10.1016/j.jinf.2012.10.010
 Sun, G., Abe, S., Takei, O. and Matsui, T. (2011) A portable screening system for onboard entry screening at international airports using a microwave radar, reflective photo sensor and thermography. Proceedings of the 2nd International Conference of ICICI-BME, Bandung, 8-9 November 2011, 107-110. doi:10.1109/ICICI-BME.2011.6108604
 Sun, G., Vinh, N.Q., Abe, S., Takei, O., Sugamata, M. and Matsui, T. (2013) A portable infection screening system designed for onboard entry screening based on multi-parameter vital signs. International Journal of E-Health and Medical Communications, in press.
 Hurt, A.C., Baas, C., Deng, Y.M., Roberts, S., Kelso, A. and Barr, I.G. (2009) Performance of influenza rapid point-of-care tests in the detection of swine lineage A(H1N1) influenza viruses. Influenza Other Respi Viruses, 3, 171-176. doi:10.1111/j.1750-2659.2009.00086.x
 Macqueen, J. (1967) Some methods for classification and analysis of multivariate observations. Proceedings of the 5th Berkeley symposium on mathematical statistics and probability, Berkeley, 1, 281-297.
 Patricia, C., Priest, P.C., Jennings, L.C. Duncan, A.R., Brunton, C.R. and Baker, M.G. (2012) Effectiveness of Border Screening for Detecting Influenza in Arriving Airline Travelers. American Journal of Public Health, 103, 1412-1418. doi:10.2105/AJPH.2008.158071
 WHO Influenza A(H1N1) patient care checklist. http://www.who.int/csr/resources/publications/swineflu/ah1n1_checklist.pdf