Disease Course and Long-Term Outcomes in Adult IgA Vasculitis Nephritis: A Prospective Observational Study

Background/Objectives: A limited number of previous studies have reported high rates of end-stage renal disease (ESRD) in adults with IgA vasculitis nephritis (IgAVN). Despite the high prevalence of the disease and the high rates of ESRD reported in the literature, no specific guidelines for adult patients have been established and there is no consensus on the management of the disease. This study aimed to prospectively investigate adults with IgAVN from a broad perspective. Methods: This investigation was designed as a prospective observational study and was conducted between 01.02.2022 and 01.10.2024. A total of 49 newly diagnosed adult (>18 years) patients with IgAVN were regularly followed up. At the end of the study, the renal remission rates, factors influencing remission, treatment data, treatment-related adverse events, and disease outcomes were determined. Results: The median follow-up time was 22 (IQR: 11-24) months. A total of 42 patients (87%) received immunosuppressive treatment in addition to the initial glucocorticoid treatment. Azathioprine (AZA) was the preferred (41%) first steroid-sparing agent. ESRD occurred in only one patient (2%), while a total of ten patients (20%) had an unfavorable outcome. The rate of nephrotic-range proteinuria (NRP) was significantly higher in the patients who did not achieve renal remission at the end of the 12-month follow-up period (9,7% vs. 60%; p = 0.02) and NRP was an independent risk factor for unfavorable outcomes [OR: 17.18; 95% CI: 1.31-224.95; p = 0.03]. A total of 16% of the patients developed an infection that required hospitalization during follow-up; these patients had a higher rate of IgAVN-associated acute kidney injury (62.5% vs. 22%; p = 0.02) and were significantly older (mean: 46 ± 15.3 vs. 65 ± 13.3; p = 0.002). One patient died of sepsis at 4 months and another died of a myocardial infarction at 32 months. Conclusions: These results suggest that adults with IgVAN do not have a high rate of ESRD if they receive effective immunosuppressive therapy. However, immunosuppressive therapy is associated with an increased risk of infection, particularly in the elderly. The presence of NRP is associated with lower long-term remission rates and has a predictive value for unfavorable outcomes.