Comparison of clinicopathological features and prognosis between IgA nephropathy and purpura nephritis in adults with diffuse endocapillary proliferation: a single-center cohort study.

BACKGROUND: Clinical manifestations and histological lesions of IgA nephropathy and Henoch-Schönlein purpura nephritis (HSPN) are different, but related, and are also correlated with the renal outcomes. This study aimed to compare the features of immunoglobulin A nephropathy (IgAN) and HSPN in adult patients with diffuse endocapillary proliferation (DEP) lesions aiming to clarify the differences and relationships in the clinicopathological findings and outcome. METHODS: Twelve patients with DEP-IgAN and 10 patients with DEP-HSPN were enrolled. Twenty four patients with IgAN (NDEP-IgAN) and matched 20 patients with HSPN (NDEP-HSPN) were enrolled at the same ratio (1:2). The clinicopathological features, clinical efficacy, and renal outcomes were analyzed in the four groups. RESULTS: DEP patients with IgAN or HSPN had worse clinical manifestations (more severe proteinuria, lower serum ALB, higher incidence of gross hematuria). The proteinuria in the DEP-HSPN group was more severe than in the DEP-IgAN group. There was no significant difference in the serum creatinine among four groups. The incidence of endothelial swelling was significantly higher in the DEP-HSPN group than in the NDEP-HSPN group and DEP-IgAN group. The S1 score of Oxford classification was more common in the DEP-IgAN group than in the DEP-HSPN. None in the DEP-IgAN group reached endpoint events during the follow-up period, while the renal outcomes were significantly poorer in the DEP-HSPN group than in the DEP-IgAN and NDEP-HSPN groups. No significant difference was observed in the cumulative renal survival among four groups (χ 2 =7.264, P=0.064), but patients in the DEP-HSPN group had markedly lower renal cumulative survival rate as compared to the NDEP-HSPN group (χ 2 =4.875, P=0.027). CONCLUSIONS: The DEP is significantly associated with more severe proteinuria and hematuria regardless the IgAN and HSPN. Among DEP patients, patients with HSPN have poor therapeutic efficacy and renal outcomes, even under active immunosuppressive therapy, as compared to those with IgAN.