Significance of histological crescent formation in patients with IgA vasculitis (Henoch-Schönlein purpura)-related nephritis: a cohort in the adult Chinese population

BACKGROUND: IgA vasculitis (IgAV, formerly Henoch-Schönlein purpura) is a type of systemic vasculitis. This study aimed to explore the clinicopathological features, treatment and renal outcomes of adult IgAV-related nephritis (Henoch-Schönlein purpura nephritis) patients with different degrees of crescent formation. METHODS: Adult patients with biopsy-proven IgAV-related nephritis in Nanjing Jinling Hospital were enrolled and divided into three groups as follows: control (no crescents, n = 257), group 1 (crescents < 25%, n = 381), and group 2 (crescents ≥25%, n = 60). The clinicopathological features, treatment and renal outcomes were compared among the three groups. RESULTS: There were no significant differences in gender and age at biopsy among the three groups. Groups with more crescents had shorter renal durations and higher prevalence of macroscopic hematuria, proteinuria and nephrotic syndrome than the control group. The presence of renal insufficiency at biopsy was similar, whereas laboratory findings indicated that patients with ≥25% crescents had higher levels of serum creatinine and blood urea nitrogen than the control and group 1. Histologically, the incidence of glomeruli-Bowman’s capsule adhesion and capillary necrosis were proportional to the degree of crescent formation. Patients with more crescents received more positive immunosuppressive therapies. During follow-up, the levels of proteinuria and hematuria were in remission after treatment, and patients without crescents had lower levels of proteinuria. At the last follow-up, the renal function had deteriorated in the control and group 1, whereas the levels of serum creatinine at biopsy and last follow-up were similar in group 2. There was a significant difference in renal survival from end-stage renal disease (ESRD) or 50% decline in renal function among the three groups (log-rank, P = 0.030). However, no association between crescent formation and renal outcomes was found after adjusting potential confounders. CONCLUSIONS: Adult IgAV-related nephritis patients with more crescents had more-severe renal manifestations and worse treatment responses, whereas the proportions of crescents were not associated with higher risks for ESRD or 50% decline in renal function. A more suitable pathological classification standard is needed to predict renal prognosis.