Behavioral assessment scale of consciousness for nonhuman primates: A Delphi study

OBJECTIVE: Nonhuman primates (NHPs) are suitable for being model animals in the study of consciousness and loss of consciousness (LoC) with a similar brain structure and function to humans. However, there is no effective consciousness assessment scale for them. This study aimed to develop a behavioral assessment scale of consciousness for NHPs. METHODS: We constructed an initial indicator framework based on the clinical consciousness disorder assessment scales and the physiological characteristics, consciousness, and arousal behavior of NHPs. A two-round online Delphi method was conducted by a multidisciplinary expert panel to construct a behavioral assessment scale of consciousness for NHPs. The indicators and descriptions were revised according to the experts’ feedback and then sent out for repeated consultations along with a summary of the results of the previous round of consultations. The accepted competencies of indicators were established with mean scores in two scoring criteria (importance and feasibility) ≥4.0, agreement rate with a rating of importance or essential ≥70.0%, and a coefficient of variation ≤0.25, as well as discussions of the research group. RESULTS: Consensus was achieved after the second round of consultations, which was completed by 28 experts who specialized in rehabilitation, neuroscience, psychology, neurosurgery, and neurology. A new behavioral assessment scale of consciousness for NHPs, including 37 items organized hierarchically within seven dimensions including visual function, auditory function, motor function, orofacial movements, arousal, brainstem reflexes, and respiration, was developed in this study. CONCLUSIONS: This study has successfully developed a behavioral assessment scale for measuring the conscious state of NHPs or NHP models with LoC. This tool is expected to facilitate future research into the underlying mechanisms of consciousness by providing a detailed and comprehensive means of measurement.