Development and preliminary validity and reliability of the montreal instrument for cat arthritis testing, for use by caretaker/owner, MI-CAT(C), via a randomised clinical trial

Challenges in the clinical assessment of feline osteoarthritis (OA)-related pain and disability impede diagnosis and treatment of the disease. A pain scale was developed for use by cat owners and caretakers, the Montreal Instrument for Cat Arthritis Testing - Caretaker/Owner (MI-CAT(C)). Following content validation and a pilot assessment (n = 11 cats with and without OA) of MI-CAT(C)-v1 reliability and validity, a randomised, double-blinded, placebo-controlled, crossover clinical trial was conducted; meloxicam efficacy in 54 OA-affected cats was evaluated using the MI-CAT(C)-v2 and locomotor activity monitoring (AM). The intra-class correlation coefficient was 0.81 for total scale intra-rater reliability, and 0.64 for inter-rater reliability; secondary owners tended to have more trouble completing the scale than did primary owners. Internal consistency assessed by Cronbach's alpha was >0.70 for the total scale, but <0.70 for subscales and subcategories. Compared to reference level, MI-CAT(C)-v2 score decreased by 17.56% with meloxicam (P < 0.05) and increased with age (P < 0.01). Night-time AM (NAM) was lower than daytime AM (P < 0.0001). Actimetry increased by 23.83% with meloxicam treatment (P < 0.0001). MI-CAT(C)-v2 scores correlated negatively with log NAM (RhoP = −0.36, P = 0.0074) and positively with age (RhoP = 0.43, P = 0.0011). These preliminary findings support the reliability and validity of the MI-CAT(C)-v2 when completed by the primary owners of OA cats. However, questions remain regarding item comprehension and internal scale structure/internal consistency. Further refinement and testing should include a comprehension analysis and exploratory factor analysis in a larger sample of cats, as well as evaluation of sensitivity/specificity to OA status in a sample of cats with and without OA, testing of responsiveness to other OA therapies and ability to distinguish treatment from placebo, and finally, development of guidelines for clinical use, such as determination of the minimum clinically important difference in scale score and thresholds for determining OA vs. non-OA status.