Prevalence and risk factors of relapse in patients with ANCA-associated vasculitis receiving cyclophosphamide induction: a systematic review and meta-analysis of large observational studies

Background. Clinical relapses are common in patients with ANCA-associated vasculitis (AAV). The aim of this systematic review was to estimate time-point prevalence and risk factors of relapse. Methods. We searched PubMed, Embase, and Cochrane Library databases from their inception to March 30, 2020. Cohorts and post-hoc studies were included for the estimation of summary cumulative relapse rates (CRRs) and adjusted hazard ratios (aHRs) with 95% confidence intervals (CIs). Sensitivity and meta-regression analyses were also performed. Results. Of the 42 eligible studies, 24 studies with 6236 participants were used for the pooled analyses of CRRs. The summary 1-year, 3-year, and 5-year CRRs were 0.12 (95% CI, 0.10-0.14), 0.33 (0.29-0.38), and 0.47 (0.42-0.52), respectively. In meta-regressions, the baseline age was positively associated with 1-year CRR. The proportion of granulomatosis with polyangiitis was positively associated with 5-year CRR. Twenty-eight studies with 5390 participants were used for the meta-analysis of risk factors for relapse, including a lower level of baseline serum creatine, proteinase 3 (PR3)-ANCA positivity at diagnosis, an ANCA rise, extrarenal organ involvement (including lung, cardiovascular, upper respiratory, and gastrointestinal involvement), intravenous (vs oral) cyclophosphamide induction, a shorter course of immunosuppressant maintenance, and maintenance with mycophenolate mofetil (vs azathioprine). Conclusions. Our systematic review demonstrated that the 1-year, 3-year, and 5-year cumulative probabilities of relapse were similar to 12%, 33%, and 47% in AAV patients receiving cyclophosphamide induction, respectively. Early identification of risk factors for relapse is helpful to the risk stratification of patients so as to achieve personalized treatment.