Preoperative risk assessment in horses: agreement and predictive value of CHARIOT (Combined Horse Anaesthetic Risk Identification and Optimisation Tool).

OBJECTIVE

To assess interobserver agreement and predictive value of the Combined Horse Anaesthetic Risk Identification and Optimisation Tool (CHARIOT) compared with the American Society of Anesthesiologists Physical Status (ASA-PS) classification system among five groups of evaluators with different levels of expertise, and to explore the association between risk scores and 7-day postoperative mortality.

STUDY

DESIGN

Prospective, observational, single-centre pilot study.

ANIMALS: A group of 50 client-owned horses.

METHODS

Each horse was assessed (ASA-PS and CHARIOT) before general anaesthesia by one evaluator from each of five groups: equine rotating intern, resident of the European College of Veterinary Anaesthesia and Analgesia (ECVAA), anaesthetist expert (ECVAA Diplomate/residency-trained), equine resident [European College of Veterinary Surgeons (ECVS) or European College of Equine Internal Medicine (ECEIM)] and European Board of Veterinary Specialisation (EBVS) Specialist (ECVS or ECEIM Diplomate). Mixed-effects Poisson regression analysed adjusted mean scores by evaluator type and scoring system, with pairwise comparisons to identify significant differences. Logistic regression and receiver operating characteristic curve analysis assessed associations between scores and 7-day postoperative mortality.

RESULTS

Adjusted mean scores (95% confidence interval) for ASA-PS and CHARIOT: anaesthesia experts 2 (1.8-2.2), 13.9 (13.4-14.3); anaesthesia residents 1.9 (1.7-2.2), 13.6 (13.1-14.1); interns 1.9 (1.7-2.1), 13.2 (12.8-13.7); equine residents 1.9 (1.7-2.1), 13.2 (12.8-13.6) and EBVS Specialists 1.8 (1.6-2), 12.7 (12.3-13.1). Pairwise differences existed between ECVAA evaluators (resident and experts) and every other group (p < 0.05). Higher scores for CHARIOT and ASA-PS were associated with increased odds of 7-day postoperative mortality (p < 0.001).

CONCLUSIONS AND CLINICAL RELEVANCE: Anaesthesia experts assigned higher risk scores with both scales. Higher scores on both scales were associated with increased mortality risk. Multicentre studies are warranted to confirm CHARIOT's predictive performance and to refine its clinical application.