Abstract
BACKGROUND: The analysis of the main features of randomized controlled trials (RCTs) on ANCA-associated vasculitis (AAV) can inform future study design. METHODS: We searched within the International Clinical Trials Registry Platform all registered RCTs on AAV from October 2008 to December 2018. Two reviewers selected studies according to pre-specified eligibility criteria. We retrieved information including countries, funding, design, sample sizes, eligibility criteria, primary outcomes (POs), and treatments. RESULTS: Among the 40 RCTs identified, 22 (55%) were conducted in Europe, 29 (72,5%) in a single country, 14 (35%) were industry-funded. The median number of patients planned to enrol was 68 (IQR 36-138). Only 28% of RCTs targeted a single vasculitis, and ANCA negative patients were not included in about 40% of studies. Interventions investigated were mainly drugs given to induce (40%) or maintain (32.5%) remission. Eighty-five percent of POs were considered being 'patient-important', but discrepancies in definition of disease states, such as remission or relapse were observed. Glucocorticoids use was part of the PO in < 25% of studies. The number of trials targeting a single disease, non-industry funded, incorporating glucocorticoids in PO, as well as the planned sample size increased over time. CONCLUSION: Despite the important achievements in the field, a better harmonization of eligibility, and outcome criteria across studies is an important objective to pursue in next future.