A novel screening method for influenza patients using a newly developed non-contact screening system

OBJECTIVES: In places of mass gathering, rapid infection screening prior to definite diagnosis is vital during the epidemic season of a novel influenza. In order to assess the possibility of clinical application of a newly developed non-contact infection screening system, we conducted screening for influenza patients. MATERIALS AND METHODS: The system is operated by a screening program via a linear discriminant analysis using non-contact derived variables, i.e., palmar pulse derived from a laser Doppler blood-flow meter, respiration rate determined by a 10-GHz microwave radar, and average facial temperature measured by thermography. The system was tested on 57 seasonal influenza (2008–2009) patients (35.7 °C ≤ body temperature ≤ 38.3 °C, 19–40 years) and 35 normal control subjects (35.5 °C ≤ body temperature ≤ 36.9 °C, 21–35 years) at the Japan Self-defense Forces Central Hospital. RESULTS: A significant linear discriminant function (p < 0.001) was determined to distinguish the influenza group from the control group (Mahalanobis D-square = 6.5, classification error rate > 10%). The system had a positive predictive value (PPV) of 93%, which is higher than the PPV value (PPV ≤ 65.4%) reported in the recent summary of studies using only thermography performed mainly in hospitals. CONCLUSIONS: The proposed system appears promising for application in accurate screening for influenza patients at places of mass gathering.