POS0248 PSYCHOMETRIC PROPERTIES OF OUTCOME MEASUREMENT INSTRUMENTS FOR ANCA-ASSOCIATED VASCULITIS: A SYSTEMATIC LITERATURE REVIEW

Background: The OMERACT Vasculitis Working Group has defined a Core Domain Set of outcome measures for ANCA-associated vasculitis (AAV). However, the psychometric properties of available outcome measurement instruments in AAV, an essential consideration when choosing among instruments, have not been summarized. Objectives: To systematically review and summarize the psychometric properties of outcome measurement instruments used in AAV. Methods: A comprehensive search of several databases (Medline, EMBASE, Cochrane, Scopus, among others) from inception to July 14, 2020 and without language limitations was conducted. Articles were included if they covered psychometric properties of instruments used in AAV (granulomatosis with polyangiitis, GPA; microscopic polyangiitis, MPA; eosinophilic granulomatosis with polyangiitis, EGPA); articles encompassing other systemic vasculitides and not presenting the data for AAV separately were excluded. 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 AAV were assessed. Risk of bias was assessed according to the COSMIN checklist. Results: From 2505 articles identified, 20 met the predefined criteria. Three were identified as development studies, 14 were validation studies, and 3 pursued both objectives. These studies provided information on 16 instruments: 8 assessing disease activity, 1 assessing disease damage, 3 assessing patient-reported outcome, 4 assessing function (Figure 1). Overall, a few psychometric properties have been considered in each study, ranging from one to five. Most of the instruments were tested in GPA only (n=7), followed by AAV as a group (GPA, MPA and EGPA; n=5), MPA and GPA (n=3), and EGPA only (n=1). Sample sizes of the studies ranged between 27 and 626 patients. The studies with a higher risk of bias, according to COSMIN definitions, were those assessing RAPID3, MVIA, ENT/GPA DAS, and ODSS. There was a wide heterogeneity of the psychometric proprieties assessed for each instrument. Validity was the most frequently assessed domain in 88% of the instruments, and few properties other than construct validity were reported (Figure 1). Within each domain, BVAS/WG for activity, VDI for damage, AAV-PRO for patient-reported outcomes, and ODSS for function were the instruments with more psychometric features assessed. For the disease activity domain, BVAS/WG showed a good validity having the highest correlation with physician global assessment (r=0.90), a good reliability (intra-observer ICC=0.62; inter-observer ICC=0.97), and good feasibility and responsiveness. For disease damage, VDI showed moderate validity (correlations with BVAS/WG at 5-year with r=0.20 and BVAS/WG at 1-year with r=0.40) and good feasibility. Among patient-reported outcomes, AAV-PRO had the best performance in terms of validity (construct validity: correlations of the 6 disease domains and EQ-5D-5L, with r ranging between -0.78 and -0.55; discriminating validity between active disease versus remission of the 6 disease domains, p Conclusion: Sixteen instruments covering the OMERACT domains of disease activity, damage, patient-reported outcome, and function had their psychometric properties assessed in the study of AAV. The majority were developed or validated for GPA only or AAV as a group. Overall, validity was the domain most frequently assessed. BVAS/WG, VDI, AAV-PRO, and ODSS were the instruments with more psychometric features assessed. More rigorous studies aimed at estimating a wider range of psychometric properties in larger numbers of patients with AAV are warranted. References: [1]Castrejon I, et al. Clin Exp Rheumatol. 2015 [2]Merkel PA, Journal of Rheumatology, July 2011 Disclosure of Interests: None declared