Variability of resting endoscopic grading for assessment of recurrent laryngeal neuropathy in horses.

The study examined the reliability of endoscopic grading for diagnosing recurrent laryngeal neuropathy in horses. It found that while expert veterinarians were consistent in their grading, there was considerable daily variation within individual horses, suggesting single-day results should be interpreted with care.

Study Objectives and Methods

• The study sought to evaluate the variability that might impact the grading of arytenoid cartilage movement in horses during resting endoscopic examination. The research team utilized a 7-grade system for this task.
• 270 draught horses were used for endoscopic recordings of the upper respiratory tract. These recordings were examined separately by 2 veterinarians to measure interobserver variability when using the 7-grade system to score laryngeal function.
• To identify intraobserver variability, both veterinarians repeated the grading on 80 randomly selected recordings.
• In 120 horses, the endoscopy procedure was done again after 24-48 hours. Videos of these were reviewed by both veterinarians, who then graded them to measure intrahorse variability.

Key Findings

• The study reported that intraobserver reliability, or the consistency within the same observer, was high with an average agreement rate of 76.3% and a kappa statistic (a measure of agreement) of 0.867.
• Similarly, the interobserver reliability, or the agreement between two observers, was robust at 63.1% with a kappa statistic of 0.765, suggesting good consistency between the veterinary observers when they conducted the examinations at the same time.
• However, the case was different when looking at intrahorse variability, or changes within the same horse over time. The same grade was assigned to 57.1% of horses at the second examination after removal of interobserver variability effects. This yielded a kappa statistic of 0.588, indicating only moderate agreement and suggesting notable variability within individual horses from one day to the next.

Conclusion

• While two experienced veterinarians showed a high level of consistency in their grading of arytenoid cartilage movement, there was only a moderate level of consistency when comparing grades assigned to the same horse at two separate examinations.
• This highlights a significant day-to-day variability within individual horses, implying that results from a single day of examination should be interpreted with caution and ideally, multiple examinations should be done for accurate diagnosis.