OBJECTIVE: Granulomatosis with polyangiitis (GPA) is an ANCA-associated vasculitis. The 2022 ACR/EULAR-endorsed classification criteria for GPA was derived using data only from adult patients. We aimed to assess the performance of the ACR/EULAR classification criteria for GPA in paediatric patients and compare it with the EULAR/Pediatric Rheumatology International Trials Organization (PRINTO)/Pediatric Rheumatology European Society (PReS)-endorsed Ankara 2008 criteria for GPA. METHODS: Retrospective data of paediatric patients with GPA in 20 centres from 9 countries were evaluated. The diagnosis of GPA was made according to the expert opinion. The sensitivity, specificity, positive predictive value, and negative predictive value of the criteria sets were evaluated. RESULTS: The study included 77 patients with GPA and 108 controls [IgA vasculitis (n = 44), Takayasu's arteritis (n = 20), microscopic polyangiitis (n = 16), polyarteritis nodosa (n = 14), Behçet's disease (n = 12), eosinophilic granulomatosis with polyangiitis (n = 1) and Cogan's syndrome (n = 1)] with a median age of 17.8 and 15.2 years, respectively. Among patients with GPA, constitutional symptoms (85.7%) and ENT involvement (79.2%) were the most common presentations. In the GPA group, 73 patients fulfilled the Ankara 2008 criteria and 69 the ACR/EULAR classification criteria. Sensitivities of the Ankara 2008 criteria and the ACR/EULAR classification criteria were 94.8% and 89.6%, while specificities were 95.3% and 96.3%, respectively. No significant difference was found between sensitivities and specificities of both classification criteria (P = 0.229 and P = 0.733, respectively). CONCLUSION: In children, both the ACR/EULAR and EULAR/PRINTO/PReS Ankara 2008 classification criteria for GPA perform well and similarly.

Centre for Paediatric Rheumatology and Autoinflammatory Diseases Department of Paediatrics and Inherited Metabolic Disorders General University Hospital and 1st Faculty of Medicine Charles University Prague Czech Republic

Children's Hospital Zagreb Zagreb Croatia School of Medicine University of Zagreb Zagreb Croatia and Faculty of Medicine Josip Juraj Strossmayer Josipa Huttlera 4 University of Osijek Osijek Croatia

Department of Biomedical Sciences Humanitas University Milan Italy

Department of Experimental and Clinical Medicine University of Florence Italy and Internal Interdisciplinary Medicine Unit Careggi University Hospital Florence Italy

Department of Neurosciences Rehabilitation Ophthalmology Genetics Maternal and Child Health University of Genoa Genoa Italy

Department of Paediatric Rheumatology Astrid Lindgren Children's Hospital Stockholm Sweden

Department of Pediatric Rheumatology Ankara City Hospital Ankara Turkey

Department of Pediatric Rheumatology Dr Sami Ulus Maternity and Child Health and Diseases Training and Research Hospital Ankara Turkey

Department of Pediatric Rheumatology Hacettepe University Faculty of Medicine Ankara Turkey

Department of Pediatric Rheumatology Marmara University Medical School Istanbul Turkey

Department of Pediatric Rheumatology Umraniye Training and Research Hospital Istanbul Turkey

Department of Pediatrics Division of Clinical Immunology Rheumatology and Allergology University of Zagreb School of Medicine Centre of Reference for Paediatric and Adolescent Rheumatology of Ministry of Health of the Republic Croatia University Hospital Centre Zagreb Zagreb Croatia

Division of Nephrology Dialysis Transplantation IRCCS Istituto Giannina Gaslini Genoa Italy

Division of Pediatric Rheumatology University of California San Francisco California USA

Division of Rheumatology Department of Medicine; Division of Epidemiology Department of Biostatistics Epidemiology and Informatics University of Pennsylvania Philadelphia PA USA

Division of Rheumatology Department of Pediatrics King Faisal Specialist Hospital and Research Center College of Medicine Al Faisal University Riyadh Saudi Arabia

Nephrology and Dialysis Division IRCCS Humanitas Research Hospital Milan Italy

Nephrology and Dialysis Unit Meyer Children's Hospital Florence Italy and Department of Biomedical Experimental and Clinical Sciences University of Florence Italy

Pediatric Nephrology and Rheumatology Faculty of Medicine Akdeniz University Antalya Turkey

Pediatric Rheumatology East Jeddah Hospital Jeddah Saudi Arabia

Pediatric Rheumatology Service Dana Dwek Children's Hospital Tel Aviv Medical Center Tel Aviv University Tel Aviv Israel

Pediatric Rheumatology Unit Hospital das Clinicas HCFMUSP Faculdade de Medicina Universidade de Sao Paulo São Paulo Brazil

UOC Rheumatology and Autoinflammatory diseases IRCCS Istituto Giannina Gaslini Genoa Italy

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