OBJECTIVES: To analyse the differences between patients with granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA) entered into randomised clinical trials (RCTs) and those followed in large observational cohorts. METHODS: The main characteristics and outcomes of patients with generalised and/or severe GPA or MPA with a five-factor score ≥ 1 enrolled in the French Vasculitis Study Group (FVSG) or the US-Canadian-based Vasculitis Clinical Research Consortium cohorts were compared to those enrolled in one of 2 FVSG clinical RCTs (WEG91, WEGENT) or 3 European Vasculitis Society clinical trials (CYCLOPS, CYCAZAREM, IMPROVE). RESULTS: 657 patients (65.3% with GPA) in RCTs were compared to 437 in cohorts (90.6% with GPA). RCT patients were older at diagnosis than the cohort patients (56.6 ± 13.9 vs. 46.8 ± 17.3 years), had higher Birmingham vasculitis activity score (19.5 ± 9.1 vs. 16.9 ± 7.4), and more frequent kidney disease (84.0% vs. 54.9%) but fewer ear, nose, and throat symptoms (56.8% vs. 72.2%). At 56 months post-diagnosis, mortality and relapse rates, adjusted for age and renal function, were higher for patients with GPA in RCTs vs. cohorts (10.7% vs. 2.5% [p=0.001] and 22.5% vs. 15.6% [p=0.03], respectively) but similar for patients with MPA (6.2% vs. 6.6% [p=0.92] and 16.6% vs. 10.1% [p=0.39], respectively). CONCLUSIONS: Patients with GPA or MPA in RCTs and those in observational cohorts show important differences that should be remembered when interpreting results based on these study populations.

Boston University Vasculitis Center Boston USA

Center for Vasculitis Care and Research Cleveland USA

Competence Centre for Clinical Research Skane University Lund Sweden

Department of Biostatistics University of South Florida Tampa USA

Department of Ear Nose and Throat Rigshospitalet Copenhagen Denmark

Department of Internal Medicine National Referral Center for Necrotising Vasculitides and Systemic Sclerosis Department of Internal Medicine Hôpital Cochin University Paris Descartes Paris France

Department of Nephrology and Transplantation Lund University Skane University Hospital Malmö Sweden

Department of Nephrology Charles University and General University Hospital 1st Faculty of Medicine Prague Czech Republic

Department of Nephrology Nuffield Orthopaedic Centre University of Oxford Oxford UK

Department of Nephrology Royal Berkshire Hospital Reading Berkshire UK

Division of Nephrology and Department of Clinical Epidemiology and Biostatistics McMaster University Hamilton Canada

Division of Rheumatology Mayo Clinic Rochester USA

Division of Rheumatology McMaster University Hamilton Canada

Division of Rheumatology University of Toronto Canada

Division of Rheumatology University of Toronto Canada and Department of Internal Medicine National Referral Center for Necrotising Vasculitides and Systemic Sclerosis Department of Internal Medicine Hôpital Cochin University of Paris France

Division of Rheumatology University of Utah Salt Lake City USA

Klinikum Offenbach Offenbach Germany

Pulmonary and Critical Care Medicine Mayo Clinic Rochester USA

School of Immunity and Infection University of Birmingham Birmingham UK

University of Cambridge and Lupus and Vasculitis Unit Addenbrookes Hospital Cambridge UK

Vasculitis Center Division of Rheumatology University of Pennsylvania Philadelphia USA

Vasculitis Center University of Pittsburgh Medical Center Pittsburgh USA

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