Meta‐analysis evaluating resting laryngeal endoscopy as a diagnostic tool for recurrent laryngeal neuropathy in the equine athlete

Summary Background Resting endoscopy has commonly been used as a method to predict laryngeal function at exercise. Objectives To perform a meta‐analysis to determine the sensitivity and specificity of resting laryngeal endoscopy to predict clinical recurrent laryngeal neuropathy at exercise. Study design Meta‐analysis. Methods Manuscripts were included if data were available for both resting and exercising airway function on all or a subset of horses. Normal resting endoscopy was defined as laryngeal grades 1 or 2 on a 4‐/7‐point scale or 1, 2 or 3 on a 5‐point scale and normal dynamic endoscopy as a dynamic laryngeal grade A. Results Twelve studies including 1827 horses were evaluated. A small proportion of horses with grade 1 or grade 2 laryngeal function at rest, 3.5 and 11.9%, respectively, were identified as having abnormal laryngeal function at exercise. Within the horses with grade 3 laryngeal function at rest, 16% were classified as grade A, 26.4% as grade B and 57.6% as grade C at exercise. Worsening subgrades within resting grade 3 demonstrated an increasing proportion of complete or partial paralysis at exercise. The sensitivity and specificity of resting endoscopy was 74.4 and 95.1%, respectively, and the positive and negative predictive values were 85.6 and 90.5% respectively. Main limitations Use of two separate grading systems for evaluating resting laryngeal function. Other forms of dynamic airway collapse were not evaluated. Conclusions Resting endoscopy is sensitive and highly specific for predicting laryngeal function at exercise. Dynamic endoscopy is important to assess multiple causes of airway collapse.