Relapse Predictors of Idiopathic Retroperitoneal Fibrosis: A Long-Term Cohort Study.

Objective: This study aims to identify predictive factors for the relapse of idiopathic retroperitoneal fibrosis (IRF) and provide instructions for the optimization of the maintenance therapy. Methods: All patients with a clinical diagnosis of IRF were enrolled and followed up every 3-6 months. Their clinical characteristics, laboratory data and treatment strategies were recorded at each visit. Results: 96 IRF patients (77 males and 19 females) with a median age of 55 years (interquartile range [IQR], 50-61) were enrolled. The median follow-up time was 2.50 (IQR, 1.75-4.13) years. During the follow-up, 21 patients experienced at least one relapse, with cumulative relapse rates of 10.6%, 32.3%, and 62.4% at 2.5, 5, and 7.5 years, respectively. Initial hydronephrosis was an independent predictor of relapse (Hazard ratio [HR], 5.35; p=0.001). Discontinuation of maintenance therapy (HR, 3.41; 95% CI, 1.4-8.314; p=0.007) was closely associated with relapse. Use (HR, 0.12; p<0.001) and dose (HR, 0.73; p=0.01) of glucocorticoids (GC) in maintenance period were protective factors against relapse. Among patients with hydronephrosis, those who discontinued GC had a higher relapse rate (p=0.009). GC monotherapy or combined immunosuppressants (IM) therapy were more effective in preventing relapse than IM alone (p<0.001). Conclusion: Our study reveals that initial hydronephrosis and GC withdrawal during maintenance therapy are significant predictors of IRF relapse. Long-term, low-dose GC therapy is benefit for maintaining remission and preventing relapse, especially in patients with initial hydronephrosis.