Risk assessment in equine anesthesia: a first evaluation of the usability, utility and predictivity of the two-part CHARIOT.

Introduction: An accurate risk score that can predict peri-anesthetic morbidity and mortality in equine patients could improve peri-operative management, outcome and client communication. Materials and methods: Three hunded horses underwent pre-anesthetic risk assessment using the American Society of Anesthesiologists-Physical Status augmented with equine-specific diseases (ASA-PS-Equine), a multifactorial 10-part rubric risk scale (10-RS), and a combination of both, the Combined horse anesthetic risk identification and optimization tool (CHARIOT). Intra-and post-anesthetic complications, the recovery phase and mortality were recorded over a period of 7 days following general anesthesia. To compare the utility and predictive power of the 3 scores, data were analyzed using binominal logistic regression ( Results: All scores showed statistically significant associations with various intra-anesthetic complications and parameters of the recovery phase. The discriminant ability of the scores related to the occurrence of intra-anesthetic (AUC = 0.6093-0.6701) and post-anesthetic (AUC = 0.5373-0.6194) complications was only low. The highest diagnostic accuracy for all scores was observed for overall mortality (AUC = 0.7526-0.7970), with the ASA-PS-Equine differentiating most precisely (AUC = 0.7970; 95% CI 0.7199-0.8741). Inter-observer reliability was fair for the 10-RS (κ = 0.39) and moderate for the ASA-PS-Equine (κ = 0.52). Patient assignment to the CHARIOT was predominantly rated as rather easy and quick or very quick. Limitations and conclusion: The main limitations of the study are the monocentric study design and failure to obtain the full range of points. In conclusion, all 3 scores provide useful information for predicting the mortality risk of equine patients undergoing general anesthesia, whereas intra-and postoperative complications cannot be predicted with these scores.