364. An International Delphi Exercise to Identify the of Importance for Measuring Response in ANCA-Associated Vasculitis

Background/Objectives: ANCA-associated vasculitis (AAV) is characterized by fluctuating levels of disease activity. Randomized controlled trials (RCTs) in AAV have used multiple instruments to define active disease or remission as a dichotomous outcome. However, no formal criteria exist to measure treatment response in AAV. This Delphi exercise aimed to reach consensus about which measures are considered by patients and physicians to be most important when assessing response to treatment in clinical trials in AAV. Methods: An international 3-round online Delphi exercise was conducted in English. Survey participants included experts in AAV and patients with AAV. Ite in the Delphi were based on a previous systematic literature review of outcome measures in RCTs in AAV, and suggestions from a Steering Committee comprised of vasculitis experts and patients with AAV. Survey participants were asked to rate (on a scale of 1-9) the importance of each item when assessing response to treatment in an RCT in AAV. Ite scored 7-9 by ≥70% participants were considered to be highly important, and ite scored 1-3 by ≥70% participants were considered to be of limited importance. Results: In total, 265 participants completed three rounds of the Delphi, including 176 physicians with expertise in AAV and 89 patients with AAV. Physicians were from six continents; the majority from Europe [n=81 (46%)] or North America [n=50 (28%)]. Most physicians specialized in rheumatology [n=105 (60%)] or nephrology [n=50 (28%)]. All physicians were in practice for at least 2 years (two-thirds >10 years) and responsible for managing ≥30 patients with AAV; over half of the physicians managed >75 patients with AAV. Patients with AAV were from four continents, with most located in North America [n=63 (71%)] or Europe [n=23 (26%)] with a diagnosis of GPA [n=72 (81%)] or MPA [n=17 (19%)]. The majority of patients with AAV were female [n=61 (69%)], ages 50-79 years [n=67 (75%)], were diagnosed in the past 10 years [n= 62 (69%)], and were currently on treatment [n=62 (70%)]. The most highly rated ite of response (Table 1) involved disease activity [extent of organ involvement, physician global assessment], mortality [survival], and patient-reported outcomes [patient global assessment and health-related quality of life measures]. Achievement of BVAS ≤1 and BVAS of 0 were highly rated only by physicians. Ite highly rated only by patients included laboratory measures [changes on urinalysis and acute phase reactants], pain, and fatigue. Additional ite related to organ damage and treatment-related adverse events were highly rated by both patients and physicians. There were no ite rated of limited importance by both groups. Conclusions: In this Delphi exercise, there was consensus between international experts in AAV and patients with AAV on many ite considered important to measure when assessing response to treatment in RCTs in AAV. There were also some ite rated as highly important by only physicians or only patients. These data provide insights into how to evaluate this complex form of vasculitis and will inform the next steps in the development of treatment response criteria in AAV. Disclosures: RC as an employee at the Parker Institute, Bispebjerg and Frederiksberg Hospital (RC) is supported by a core grant from the Oak Foundation (OCAY-18-774-OFIL). DJ has received research grants from Chemocentryx, GSK, Roche/Genentech and Sanofi-Genzyme. He has received consultancy fees from Astra-Zeneca, Boehringer-Ingelheim, Celgene, ChemoCentryx, Chugai, GSK, InflaRx, Insmed and Takeda. He is supported by the NIHR Cambridge Biomedical Research Centre (BRC-1215-20014). CL reports research support from AstraZeneca, Bristol Myers-Squibb, GlaxoSmithKline, Genentech. Non-paid consultant: AbbVie, AstraZeneca, Bristol Myers-Squibb. AM received consultant fees and speaker honoraria from Celgene and Roche Chugai. CP reports receiving funds for the following activities: Consulting: ChemoCentryx, Genentech/Roche, Genzyme/Sanofi, AstraZeneca, GlaxoSmithKline; Research support from Pfizer. PM reports receiving funds for the following activities: Consulting: AbbVie, Biogen, AstraZeneca, Boeringher-Ingelheim, Bristol-Myers Squibb, CSL Behring, ChemoCentryx, Forbius, Genentech/Roche, Genzyme/Sanofi, GlaxoSmithKline, InflaRx, Jannsen, Kiniksa, Kyverna, Magenta, Norvartis, Pfizer, Sparrow, Takeda, Talaris; Research Support: AstraZeneca, Boeringher-Ingelheim, Bristol-Myers Squibb, ChemoCentryx, Forbius, Genentech/Roche, GlaxoSmithKline, InflaRx, Sanofi; Royalties: UpToDat