Minimal clinically-important differences for the "Liverpool Osteoarthritis in Dogs" (LOAD) and the "Canine Orthopedic Index" (COI) in dogs with osteoarthritis.

OBJECTIVE: Osteoarthritis is the most common joint disease in companion animals. Several client-report outcome measures (CROMs) have been developed and validated to monitor patients and their response to treatment. However, estimates for minimal clinically-important differences for these CROMs in the context of osteoarthritis have not been published.

PATIENTS AND METHODS: Data from the Clínica Veterinária de Cães (Portuguese Gendarmerie Canine Clinic) clinical records were extracted. Baseline and 30-day post-treatment follow-up data from 296 dogs treated for hip osteoarthritis were categorized based on an anchor question, and estimates of minimal clinically-important differences (MCIDs) using distribution-based and anchor-based methods were performed.

RESULTS: For the LOAD, the anchor-based methods provided a MCID estimate range of -2.5 to -9.1 and the distribution-based methods from 1.6 to 4.2. For the COI, the anchor-based methods provided a MCID estimate range of -4.5 to -16.6 and the distribution-based methods from 2.3 to 2.4. For the dimensions of COI, values varied from -0.5 to -4.9 with the anchor-based methods and from 0.6 to 2.7 with the distribution-based methods. Receiver operator characteristic curves provided areas under the curve >0.7 for the COI, indicating an acceptable cut-off point, and >0.8 for the LOAD, indicating an excellent cut-off point.

CONCLUSION: Our estimates of MCIDs for dogs with OA were consistent with previously proposed values of -4 for the LOAD and -14 for the COI in a post-surgical intervention context. ROC curve data suggest that LOAD may more reliably differentiate between anchor groups. We also presented estimates from COI of -4 for Stiffness, Function, and Gait and -3 for quality of life. These estimates can be used for research and patient monitoring.