Client-specific outcome measure for chronic osteoarthritis pain assessment in horses.

Abstract

INTRODUCTION: Osteoarthritis (OA) is a prevalent cause of chronic pain and lameness in horses. Whereas lameness can be quantified using objective measures, the assessment of OA-associated pain remains challenging. This study aimed to evaluate the applicability of the Client-Specific Outcome Measure (CSOM), a tool widely used in small animals, for the assessment of chronic OA pain in horses through caretaker evaluation. METHODS: Seventeen privately owned horses with confirmed OA were enrolled in a 20-week randomized, double-blind, placebo-controlled study. For each horse, three individual pain-related indicators (CSOM items) were identified through a veterinarian-caretaker consultation. The selected items were regularly scored (0-4), and the scores were summed to obtain a total CSOM score (CSOM-sum). The CSOM-sum was compared with other pain assessment measures, including a caretaker-assigned visual analogue scale (VAS-own), a veterinarian-assigned visual analogue scale (VAS-exp), subjective lameness scores, and a gait asymmetry index. RESULTS: The CSOM-sum showed moderate but significant correlations with all other pain and lameness measures (&#x202f;=&#x202f;0.49-0.60,&#x202f;<&#x202f;0.05). In particular, CSOM-sum correlated with gait asymmetry (r&#x209b;&#x202f;=&#x202f;0.434,&#x202f;<&#x202f;0.0001); subgroup analysis revealed a moderate correlation in treated horses (&#x202f;=&#x202f;0.4539,&#x202f;=&#x202f;0.0025) and a higher correlation in controls (&#x202f;=&#x202f;0.5536,&#x202f;=&#x202f;0.0006). The VAS-own and VAS-exp scores showed good overall agreement (bias&#x202f;=&#x202f;-4.76&#x202f;mm; ICC&#x202f;=&#x202f;0.727; ICC_T&#x202f;=&#x202f;0.625; ICC_C&#x202f;=&#x202f;0.838), although with relatively wide limits of agreement. The internal consistency of the CSOM items was high (Cronbach's&#x202f;=&#x202f;0.81 overall; &#x3b1;_T&#x202f;=&#x202f;0.787; &#x3b1;_C&#x202f;=&#x202f;0.890). DISCUSSION: These findings indicate that, provided relevant items are carefully identified, the CSOM may represent a valuable complementary tool for assessing and monitoring pain severity in horses under field conditions.