Validity and Responsiveness of the Generic Health-Related Quality of Life Instrument (VetMetrica™) in Cats With Osteoarthritis. Comparison of Vet and Owner Impressions of Quality of Life Impact.

E Marian Scott,M Lesley Wiseman-Orr,Andrea M Nolan,Nathalie J Dowgray,Alexander J German,Vinny Davies,Jacqueline Reid,Cory E Noble

doi:10.3389/fvets.2021.733812

Abstract

Validity is not an inherent property of a measurement scale and so evidence for validity relating to its use for particular purposes, with defined populations and in specified contexts must be accumulated. We have published the development of a web-based, generic health-related quality of life instrument (VetMetrica™) to measure the affective impact of chronic disease in cats and provided evidence for its validity in a mixed population of cats, some of which, according to veterinary judgement, were healthy and others of which were suffering from chronic conditions likely to affect their quality of life, often with multiple co-morbidities present. The first aim of the current study was to demonstrate the construct validity of the VetMetrica™ generic instrument when used with cats suffering from osteoarthritis, by testing the hypothesis that the health-related quality of life profile of cats with different severities of osteoarthritis would differ and by demonstrating convergent validity between the health-related quality of life profile scores and independently quantified vet-assessed pain and quality of life impact scores. The latter involved simple correlation analysis and investigation of the relationship between health-related quality of life domain scores and vet-assessed scores, when adjusted for other potential explanatory variables including number of comorbidities and age. Responsiveness—the ability to detect clinically relevant change—is an essential quality for an evaluative instrument and it also provides evidence for “longitudinal validity”. Therefore, a second aim of this study was to demonstrate that changes in health-related quality of life domain scores concurred with the clinician's impression of change over time in the health status of cats with osteoarthritis, thus providing evidence for the instrument's responsiveness. Previously, we have reported disagreement between owner and vet impression as to health status in cats in general, but not in relation to any specific disease. Accordingly, the third study aim was to investigate the extent of agreement or disagreement between owner impression of the impact of osteoarthritis on their cats' quality of life and vet impression of such impact. Fifty one percentage of cat owners believed their cats to be perfectly healthy despite a clinician diagnosis of osteoarthritis

Highlights

Osteoarthritis (OA) is a common painful chronic disease in cats with a greater prevalence than was previously recognised [1]
Data were collected from owners of 56 cats with a diagnosis of OA attending first opinion practises, feline specialist practises, and the University of Glasgow Small Animal Hospital (UGSAH) for previously conducted field studies relating to the feline VetMetricaTM healthrelated quality of life (HRQL) instrument [15]
The mean HRQL domain score was less for cats in the moderate-severe OA group compared with the mild OA group (Table 2; p < 0.001 for all), providing evidence for construct validity

Summary

Introduction

Osteoarthritis (OA) is a common painful chronic disease in cats with a greater prevalence than was previously recognised [1]. Its effective management is underpinned by the ability to measure pain reliably, and suitable measures of clinical impact are required Such instruments should monitor pain effectively in an individual, enabling the selection of treatment with known efficacy. Several owner-report clinical metrology instruments have been developed [2, 3], which measure the functional limitations caused by OA, whilst there has been interest in developing activity monitors for cats [4]. For veterinary orthopaedic studies, guidelines have been published that recognise the important contribution of the latter, given the recommendation that at least one owner-reported QOL instrument should be included, alongside at least one validated functional outcome (such as activity monitors and clinical metrology instruments) [9]

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