Evaluation of videoendoscopic examinations of arytenoid function in the 2-year-old Thoroughbred: Can we all agree?

This study evaluates how variously experienced veterinarians agree when assessing the arytenoid function (part of the horse’s larynx) in two-year-old Thoroughbreds, and highlights discrepancies in these assessments. The study utilized videoendoscopy, a routine procedure in prepurchase horse examinations. It suggests that the grading scale for the arytenoid function and the statistical methods used for analysis could have influenced disagreements among the veterinarians in their final assessments.

Study Design and Methods

• The study was an observational cohort design, focusing on the reliability and agreement in assessing the arytenoid function in horses.
• A total of 114 Upper Respiratory Tract (URT) videoendoscopic examinations of two-year-old Thoroughbreds were evaluated by 10 veterinarians, grouped based on their professional experience.
• The arytenoid function was graded using the widely known Havemeyer ordinal scale, and later these grades were classified dichotomously into two categories: ‘meets conditions of sale’ (MCS) or ‘does not meet conditions of sale'(DNMCS).
• The purpose of the study was to identify the interobserver and intraobserver agreement in these evaluations by measuring them using Fleiss’ kappa (for the interobserver agreement across all 10 veterinarians) and Cohen’s unweighted (k) and Cohen’s linear weighted kappa (Ck) for the intraobserver and interobserver agreement within the five experience-based subgroups.

Results and Findings

• The overall interobserver agreement, when using ordinal scales, ranged from fair to average depending on the methodology used to gauge it.
• However, the agreement improved notably when the results were classified into the two categories (MCS and DNMCS), indicating that the dichotomous classification resulted in a high level of agreement among vets.
• Meanwhile, the intraobserver agreement (agreement within individual vets looking at the same case multiple times) was also within the fair to good range on both criteria- ordinal and dichotomous scales.
• The study did identify that a veterinarian’s experience level appears to impact their assessments, hinting at a need for standardized training to achieve more uniform evaluations.

Conclusions

• The study observes that despite having a well-defined arytenoid function grading scale, there’s a degree of subjectivity in assessments among veterinarians. This subjectivity creates a possibility for inconsistencies especially critical during pre-purchase equine inspections.
• These variations in the agreement might depend more on the grading scales used and the statistical methods employed for analysis rather than individual interpreters.
• The researchers recommend conducting future studies pre- and post-veterinarian training to verify if the level of agreement in evaluations can be improved through standardized training.