Reliability of a quantitative rating scale for assessment of horses with distal tarsal osteoarthritis.

The researchers in this study sought to develop and test a reliable radiographic rating scale for assessing distal tarsal osteoarthritis in horses.

Development of the Radiographic Rating Scale

• The study aimed at creating a radiographic rating scale to evaluate distal tarsal osteoarthritis, a common joint problem in horses.
• Via an expert consultation or Delphi process, seven particular radiographic features were identified as significant markers of this condition.
• These features were incorporated into a rating scale, which essentially consisted of a 100-mm-long visual analog scale.

Application and Testing of the Rating System

• Nine experienced equine veterinarians were asked to utilize this new rating system on two separate occasions.
• The veterinarians evaluated three different sets of tarsal radiographs, each of which contained four specific standard radiographic views.
• Additionally, these veterinarians were asked to use a verbal descriptive rating system for the same sets of radiographs.

Evaluation of Reliability

• The reliability of the rating scale was assessed using Bland-Altman plots and calculating the agreement limits of 95%, a standard statistical approach in rating and scale reliability testing.
• A further statistical analysis, known as Analysis of variance (ANOVA) was performed to identify any significant differences between the ratings provided by different evaluating veterinarians, from different views and at both assessment occasions.

Research Findings

• There was a noticeable difference in the distal tarsal osteoarthritis rating among the nine assessors.
• The accuracy of the second ratings varied quite significantly. They were observed to be as high as 16 mm more or as low as 18 mm less than the initial ratings.
• The study identified significant variables using two different types of ANOVA. The univariable analysis revealed “joint,” “assessor,” and “assessment,” while the multivariable analysis showed interactions between “joint and assessor” and “assessor and assessment.”
• In conclusion, the newly developed radiographic rating scale was found to be less reliable than the traditional verbal descriptive rating scale for interpreting distal tarsal osteoarthritis.