Childhood-onset granulomatosis with polyangiitis and microscopic polyangiitis: systematic review and meta-analysis.

BACKGROUND: The data from cohorts of childhood-onset granulomatosis with polyangiitis (GPA) and microscopic polyangiitis (MPA) remain scarce and heterogeneous. We aimed to analyse the features at presentation, therapeutic approaches and the disease course of these rare diseases.

METHODS: Electronic searches of Medline and the Cochrane Central Register of Controlled trials database were conducted. We also checked the reference lists of the studies included and other systematic reviews, to identify additional reports. We included all cohorts, cross-sectional studies or registries reporting features at presentation or outcomes in patients with a diagnosis of childhood-onset GPA or MPA (age <18 years). The pooled prevalence of clinical manifestations at presentation, ANCA and induction therapies for GPA and MPA was calculated.

RESULTS: We reviewed 570 full texts and identified 14 studies on GPA and 8 on MPA. Childhood-onset GPA and MPA occurred predominantly in female subjects during adolescence. For GPA, ear-nose-throat (ENT) disease (pooled prevalence 82 % [95 % CI 78-87]), constitutional symptoms (73 % [95 % CI 55-88]), renal (65 % [95 % CI 49-79]), and lower respiratory tract (61 % [95 % CI 48-74]) manifestations were the most frequently reported at presentation. Renal disease was a hallmark of MPA (94 % [95 % CI 89-97]). ANCA were detected in >90 % of children with GPA or MPA. Combined corticosteroids and cyclophosphamide was the most frequently used first remission-inducing treatment for GPA (76 % [95 % CI 69-82]) and MPA (62 % [95 % CI 20-96]). Relapses occurred more frequently in GPA (67-100 %) than in MPA (25-50 %). The leading causes of death were the disease itself, and infections.

CONCLUSIONS: Childhood-onset MPA and GPA remain severe diseases with frequent relapses and a high cumulative morbidity. Survival and disease-free survival need to be improved.