BackgroundEvaluation of physical function is fundamental in the management of idiopathic inflammatory myopathies (IIMs). Patient-Reported Outcome Measurement Information System (PROMIS) is a National Institute of Health initiative established in 2004 to develop patient-reported outcome measures (PROMs) with improved validity and efficacy. PROMIS Physical Function (PF) short forms have been validated for use in IIMs [1].ObjectivesTo investigate the physical function status of IIM patients compared to those with non-IIM autoimmune diseases (AIDs) and healthy controls (HCs) utilizing PROMIS PF data obtained in the coronavirus disease-2019 (COVID-19) Vaccination in Autoimmune Diseases (COVAD) study, a large-scale, international self-reported e-survey assessing the safety of COVID-19 vaccines in AID patients [2].MethodsThe survey data regarding demographics, IIM and AID diagnosis, disease activity, and PROMIS PF short form-10a scores were extracted from the COVAD study database. The disease activity (active vs inactive) of each patient was assessed in 3 different ways: (1) physician’s assessment (active if there was an increased immunosuppression), (2) patient’s assessment (active vs inactive as per patient), and (3) current steroid use. These 3 definitions of disease activity were applied independently to each patient. PROMIS PF-10a scores were compared between each disease category (IIMs vs non-IIM AIDs vs HCs), stratified by disease activity based on the 3 definitions stated above, employing negative binominal regression model. Multivariable regression analysis adjusted for age, gender, and ethnicity was performed clustering countries, and the predicted PROMIS PF-10a score was calculated based on the regression result. Factors affecting PROMIS PF-10a scores other than disease activity were identified by another multivariable regression analysis in the patients with inactive disease (IIMs or non-IIM AIDs).Results1057 IIM patients, 3635 non-IIM AID patients, and 3981 HCs responded to the COVAD survey until August 2021. The median age of the respondents was 43 [IQR 30-56] years old, and 74.8% were female. Among IIM patients, dermatomyositis was the most prevalent diagnosis (34.8%), followed by inclusion body myositis (IBM) (23.6%), polymyositis (PM) (16.2%), anti-synthetase syndrome (11.8%), overlap myositis (7.9%), and immune-mediated necrotizing myopathy (IMNM) (4.6%). The predicted mean of PROMIS PF-10a scores was significantly lower in IIMs compared to non-IIM AIDs or HCs (36.3 [95% (CI) 35.5-37.1] vs 41.3 [95% CI 40.2-42.5] vs 46.2 [95% CI 45.8-46.6], P < 0.001), irrespective of disease activity or the definitions of disease activity used (physician’s assessment, patient’s assessment, or steroid use) (Figure 1). The largest difference between active IIMs and non-IIM AIDs was observed when the disease activity was defined by patient’s assessment (35.0 [95% CI 34.1-35.9] vs 40.1 [95% CI 38.7-41.5]). Considering the subgroups of IIMs, the scores were significantly lower in IBM in comparison with non-IBM IIMs (P < 0.001). The independent factors associated with low PROMIS PF-10a scores in the patients with inactive disease were older age, female gender, and the disease category being IBM, PM, or IMNM.ConclusionPhysical function is significantly impaired in IIMs compared to non-IIM AIDs or HCs, even in patients with inactive disease. The elderly, women, and IBM groups are the worst affected, suggesting that developing targeted strategies to minimize functional disability in certain groups may improve patient reported physical function and disease outcomes.References[1]Saygin D, Oddis CV, Dzanko S, et al. Utility of patient-reported outcomes measurement information system (PROMIS) physical function form in inflammatory myopathy. Semin Arthritis Rheum. 2021; 51: 539-46.[2]Sen P, Gupta L, Lilleker JB, et al. COVID-19 vaccination in autoimmune disease (COVAD) survey protocol. Rheumatol Int. 2022; 42: 23-9.AcknowledgementsThe authors thank all respondents for filling the questionnaire. The authors thank The Myositis Association, Myositis India, Myositis UK, the Myositis Global Network, Cure JM, Cure IBM, Sjögren’s India Foundation, EULAR PARE, and various other patient support groups and organizations for their invaluable contribution in the dissemination of this survey among patients which made the data collection possible. The authors also thank all members of the COVAD study group.Disclosure of InterestsNone declared