Toward Development and Evaluation of Pain Level-Rating Scale for Emergency Triage based on Vocal Characteristics and Facial Expressions

In order to allocate the healthcare resource, triage classification system plays an important role in assessing the severity of illness of the boarding patient at emergency department. The self-report pain intensity numerical-rating scale (NRS) is one of the major modifiers of the current triage system based on the Taiwan Triage and Acuity Scale (TTAS). The validity and reliability of self-report scheme for pain level assessment is a major concern. In this study, we model the observed expressive behaviors, i.e., facial expressions and vocal characteristics, directly from audio-video recordings in order to measure pain level for patients during triage. This work demonstrates a feasible model, which achieves an accuracy of 72.3% and 51.6% in a binary and ternary pain intensity classification. Moreover, the study result reveals a significant association of current model and analgesic prescription/patient disposition after adjusted for patient-report NRS and triage vital signs.