The effects of plasma exchange in patients with ANCA-associated vasculitis: an updated systematic review and meta-analysis

OBJECTIVE: To assess the effects of plasma exchange on important outcomes in anti-neutrophil cytoplasm antibody (ANCA)-associated vasculitis (AAV). DESIGN: Systematic review and meta-analysis of randomised controlled trials. ELIGIBILITY CRITERIA: Randomised controlled trials investigating effects of plasma exchange in patients with AAV or pauci-immune rapidly progressive glomerulonephritis and at least 12 months' follow-up. INFORMATION SOURCES: Prior systematic reviews, updated by searching Medline, Embase, and CENTRAL to July 2020. RISK OF BIAS: Reviewers independently identified studies, extracted data, and assessed the risk of bias using the Cochrane Risk of Bias tool. SYNTHESIS OF RESULTS: Meta-analyses were conducted using random effects models to calculate risk ratios and 95% confidence intervals. Quality of evidence was summarised in accordance with GRADE methods. Outcomes were assessed after at least12 months of follow-up and included all-cause mortality, end stage kidney disease (ESKD), serious infections, disease relapse, serious adverse events, and quality of life. RESULTS: Nine trials including 1060 participants met eligibility criteria. There were no important effects of plasma exchange on all-cause mortality (relative risk 0.90 (95% CI 0.64 to 1.27), moderate certainty). Data from seven trials including 999 participants that reported ESKD demonstrated that plasma exchange reduced the risk of ESKD at 12 months (relative risk 0.62 (0.39 to 0.98), moderate certainty) with no evidence of subgroup effects. Data from four trials including 908 participants showed that plasma exchange increased the risk of serious infections at 12 months (relative risk 1.27 (1.08 to 1.49), moderate certainty). The effects of plasma exchange on other outcomes were uncertain or considered unimportant to patients. LIMITATIONS OF EVIDENCE: There is a relative sparsity of events, and treatment effect estimates are therefore imprecise. Subgroup effects at the participant level could not be evaluated. INTERPRETATION: For the treatment of AAV, plasma exchange has no important effect on mortality, reduces the 12 month risk of ESKD, but increases the risk of serious infections. FUNDING: No funding was received. REGISTRATION: This is an update of a previously unregistered systematic review and meta-analysis published in 2014.