AB0373 PSYCHOMETRIC PROPERTIES OF OUTCOME MEASUREMENT INSTRUMENTS FOR LARGE VESSEL VASCULITIS: A SYSTEMATIC LITERATURE REVIEW

Abstract

Background:Giant cell arteritis (GCA) and Takayasu arteritis (TAK) are two forms of chronic progressive large-vessel vasculitis (LVV) of unknown etiology. In 2016, the OMERACT Vasculitis Working Group proposed the development of a Core Domain Set of outcome measures for LVV including organ and arterial function, fatigue, pain, biomarkers, and death (1). Understanding the psychometric properties of outcome measurement instruments is essential when selecting among instruments to use in research; a summary of such properties for measures of LVV has not been developed.Objectives:To systematically review and summarize the psychometric properties of outcome measurement instruments used to measure the domains of the OMERACT core domain set for LVV.Methods:A comprehensive search of several databases (Medline, EMBASE, Cochrane, among others) from inception to July 14, 2020 was conducted. Articles were included if they covered psychometric properties of instruments used in LVV. Following the COSMIN and OMERACT frameworks, different psychometric properties (validity, inter- and intra-observer reliability, sensitivity to change, and feasibility) of outcome measurement instruments used in LVV (GCA and TAK) were assessed. Risk of bias was assessed according to the COSMIN checklist.Results:Among the 3534 articles identified, 15 studies focusing on the development or validation of psychometric properties on LVV met the predefined criteria. Two were development studies and 13 were validation studies. These studies provided information on 13 instruments: 5 instruments specific to TAK, 2 specific to systemic vasculitides, and 6 general, non-disease-specific instruments. No instruments specific to GCA were identified.Of the main psychometric properties assessed in the included studies, 40% had a low, 47% had moderate, and 13% had high risk of bias. Construct validity was the property most frequently assessed (in 93% of the tools) (Figure 1).In TAK, the Indian Takayasu Clinical Activity Score 2010 (ITAS2010) showed good consistency (r=0.97), reliability (intra-observer, ICC=0.60; inter-observer, ICC=0.92) and validity (correlation with Physician Global Assessment (PGA) (r=0.73)) for disease activity. Regarding disease damage, the Disease Extent Index-Takayasu (DEI-Tak) showed good validity (correlation with NIH score 94%, k=0.85). Non-specific vasculitis instruments such as the Vasculitis Damage Index (VDI) and the Birmingham Vasculitis Activity Score (BVAS) showed moderate validity in the assessment of disease damage in GCA (cumulative glucocorticoid dose and disease duration, r=0.30 and r=0.29) and TAK (cumulative glucocorticoid dose and disease duration, r=0.29 and r=0.25) in the former and disease activity in GCA in the later (PGA, r=0.50).Six non-vasculitis-specific patient-reported outcomes (PROs) instruments were identified, all showing low to moderate validity in GCA/TAK.Conclusion:The psychometric properties of 13 outcome measures to study LVV covering the OMERACT domains of disease activity, damage, and patient-reported outcomes were assessed. ITAS2010, DEI-Tak, VDI, and BVAS were the instruments with better psychometric properties for disease activity and/or damage. Disease activity and/or damage instruments specific for GCA, and validated PROs for both GCA and TAK are needed.