Secondary infection caused by high-dose immunosuppressive therapy is the most common cause of death in patients with ANCA-associated vasculitis. This study aimed to explore whether reduced-dose of immunosuppressive therapy could achieve effective remission together with less secondary infection in patients with mild to moderate ANCA-associated renal vasculitis, and to determine whether early secondary infections could accelerate the deterioration of renal function.

The efficacy and safety of reduced-dose regimen and standard regimen were compared with Fisher′s precision probability test. The renal survival rate was estimated with the Kaplan-Meier method and compared with the log-rank test. Potential variates were examined by means of the multivariate Cox hazard regression model to determine the risk factors of end-stage renal disease, while the receiver operating characteristic (ROC) curve was applied to evaluate the sensitivity and specificity of the risk factors.

A total of 58 patients were included, with 35 patients in the standard-dose glucocorticoids group and 23 in the reduced-dose glucocorticoids group. The average age of the included patients was 62.45±12.70 years, and the baseline serum creatinine was 251.35 μmol/L. 9 patients (15.52%) developed end-stage renal disease (ESRD) within 24 months (7 from the standard regimen group and 2 from the reduced-dose regemen group, P=0.21). 10 patients developed secondary infection 3 months after treatment (9 from the standard regimen group and 1 from the reduced-dose regemen group, P=0.035). Multivariate Cox regression model analysis displayed that the baseline serum creatinine (HR 0.007, 95%CI: 2.48-39.48, P=0.014), secondary infection rate within first 3 months (HR 2.28, 95% CI: 2.14-45.27, P=0.003), and persistent hematuria for more than 6 months (HR 1.723, 95%CI: 0.043-0.738, P=0.017) were risk factors of ESRD in patients with ANCA-associated renal vasculitis.

The regimen of initial reduced-dose immunosuppressive therapy could significantly reduce the secondary infection rate in patients with mild to moderate ANCA-associated renal vasculitis, while the efficacy was not inferior to that of the standard regimen. Patients who had secondary infection within the first 3 months of treatment were at higher risk of early progression to ESRD.