Abstract: FR-PO415

Long-term Prognosis and Predictive Factors of Non-Remission in IgA Nephropathy after Tonsillectomy and Steroid Pulse Therapy

Session Information

Category: Chronic Kidney Disease (Non-Dialysis)

  • 301 CKD: Risk Factors for Incidence and Progression

Authors

  • Yamaka, Kosuke, Shinshu University , Matsumoto CIty, Japan
  • Inui, Keita, Shinshu University , Matsumoto CIty, Japan
  • Yamada, Yosuke, Shinshu University , Matsumoto CIty, Japan
  • Kamijo, Yuji, Shinshu University School of Medicine, Matsumoto, Japan
Background

Tonsillectomy and steroid pulse therapy (TSP) for IgA nephropathy (IgAN) is widely performed in Japan. However, the efficacy of TSP remains controversial, partly because even though IgAN is a chronic nephritis, most studies set the primary outcome as complete remission (CR) at 1 year after TSP and do not address long-term outcome. Therefore, we followed patients who had undergone TSP for a minimum of 3 years to clarify the long-term results and predictive factors of non-remission (NR) following TSP.

Methods

This retrospective, single-center, cohort study included 63 patients who were monitored for at least 3 years after TSP for IgAN at Shinshu University Hospital. The frequency of CR (urinary total protein <0.3 g/gCre and urinary red blood cells <5/high-power field) was assessed at 1 and 3 years following TSP. Using statistical methods, the predictive factors of NR at 3 years were investigated with relation to physical examination, serology, and urinalysis items.

Results

CR was observed in 29 (46%) patients at 1 year of follow-up. Of these, 6 (10%) experienced a recurrence and 23 (36%) maintained CR at 3 years. Among the 34 (54%) patients with NR at 1 year, 10 (16%) exhibited late remission and 24 (38%) remained unchanged at 3 years. Overall, tubulointerstitial fibrosis was significantly more severe in NR patients at 3 years than in CR patients (P<0.01). Among the 29 patients who showed CR at 1 year, tubulointerstitial fibrosis in patients with a recurrence at 3 years was significantly more severe as well (P<0.05). The most useful factor for predicting NR at 3 years was the well known tubulointerstitial injury marker urinary N-acetyl-β-D-glucosaminidase (U-NAG) according to receiver operator characteristic (ROC) analysis (cut-off: 4.35 U/gCre; sensitivity: 83%; selectivity: 75%; area under ROC curve: 0.817). Even in patients with CR at 1 year, those whose U-NAG was >4.35 U/gCre were more likely to relapse within 3 years (P<0.05).

Conclusion

At 3 years following TSP for IgAN, both recurrence and late remission are observed in relatively many patients. The severity of tubulointerstitial fibrosis is considered to be related to TSP resistance, and U-NAG represents a useful predictor of long-term prognosis.