Childhood- versus adult-onset ANCA-associated vasculitides: A nested, matched case-control study from the French Vasculitis Study Group Registry.

OBJECTIVE: To investigate differences between childhood-onset ANCA-associated vasculitides (cAAVs) and matched adult-onset controls (aAAVs).

METHODS: cAAV clinical pictures at onset and outcomes were compared to a randomly selected sample of aAAV patients from the French Vasculitis Study Group Registry. Cases and controls were matched for AAV (granulomatosis with polyangiitis [GPA], microscopic polyangiitis [MPA] or eosinophilic granulomatosis with polyangiitis [EGPA]), sex and year of enrollment. Medications, disease activity and damage were prospectively recorded. Kaplan-Meier curves and the log-rank test were used to analyze case-vs.-control differences for predefined outcomes.

RESULTS: Comparing 35 cAAVs (25 GPA, 4 MPA, 6 EGPA) to 151 aAAVs (106 GPA, 17 MPA, 28 EGPA), their respective median follow-up durations were 71 and 64months (P=0.49), and, at baseline, children had less frequent myalgias (P=0.005) and peripheral neuropathy (P<0.001) but were more frequently febrile (P<0.05). Rates of renal involvement were comparable (13 [37%] cAAVs vs. 73 [48%] aAAVs; P=0.31). Initial GPA-associated ischemic abdominal pain and nasal cartilage damage were more common in cAAVs than aAAVs (P<0.05). During follow-up, the cAAV relapse rate was higher (24.5 vs. 18.7 flares per 100 patient-years; P<0.05) and, at last visit, cases had accumulated more damage, mostly ear, nose & throat sequelae (P=0.001), associated with longer maintenance therapy (P=0.03), than aAAV controls. Four (11.4%) cAAV and 13 (8.6%) aAAV patients died (P=0.53).

CONCLUSION: cAAVs are severe diseases, characterized by a higher relapse rate, more accrued damage and longer maintenance therapy than for aAAVs.