Clinical associations of renal involvement in ANCA-associated Vasculitis

Abstract Objective Renal involvement in anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis is associated with significant morbidity and higher mortality rates. This study examined clinical manifestations associated with renal involvement in ANCA-associated vasculitis within a large, international cross-sectional cohort. Methods Univariate and multivariate analyses were performed to identify clinical factors associated with renal disease, which was defined as i) a serum-creatinine >30% above normal and a fall in creatinine-clearance >25%; or ii) haematuria attributable to active vasculitis. Results The study cohort include 1230 patients from 31 countries; 723 (58.8%) presented with renal involvement: microscopic polyangiitis (82.2%), granulomatosis with polyangiitis (58.6%), and eosinophilic granulomatosis with polyangiitis (26.4%). The following clinical and laboratory factors were more common among patients with renal disease: age (OR 1.01, 95% CI 1.01–1.02), fever (OR 1.97, 95% CI 1.35–2.88), fatigue (OR 1.55, 95% CI 1.14–2.10), weight loss (OR 1.62, 95% CI 1.23–2.12), polyarthritis (OR 1.39, 95% CI 1.02–1.89), petechiae/purpura (OR 1.47, 95% CI 1.06–2.05), pulmonary haemorrhage (OR 5.23, 95% CI 1.39–19.63), gastrointestinal symptoms (OR 2.19, 95% CI 1.34–3.58), seizures (OR 3.42, 95% CI 1.26–9.30), lower serum albumin (OR 2.42, 95% CI 1.64–3.57), higher CRP (OR 2.06, 95% CI 1.04–4.06), low serum C3 at baseline (OR 3.86, 95% CI 1.30–11.53), myeloperoxidase- (OR 7.97, 95% CI 2.74–23.20) and proteinase 3-ANCA (OR 3.40, 95% CI 1.22–9.50). The following clinical factors were less common among patients with renal disease: mononeuritis multiplex (OR 0.63, 95% CI 0.41–0.98), proptosis/exophthalmos (OR 0.19, 95% CI 0.06–0.59), nasal polyps (OR 0.32, 95% CI 0.19–0.55), septal defect/perforation (OR 0.29, 95% CI 0.14–0.60), respiratory distress/pulmonary fibrosis/asthma (OR 0.08, 95% CI 0.04–0.19), and wheeze/obstructive airway disease (OR 0.29, 95% CI 0.16–0.52). Conclusion In this large international study, several clinical and laboratory factors were identified as associated with renal involvement in ANCA-associated vasculitis.