PLoS ONE (Jan 2014)

Optimal proteinuria target for renoprotection in patients with IgA nephropathy.

  • Ki Heon Nam,
  • Jeong Hae Kie,
  • Mi Jung Lee,
  • Tae-Ik Chang,
  • Ea Wha Kang,
  • Dong Wook Kim,
  • Beom Jin Lim,
  • Jung Tak Park,
  • Young Eun Kwon,
  • Yung Ly Kim,
  • Kyoung Sook Park,
  • Seong Yeong An,
  • Hyung Jung Oh,
  • Tae-Hyun Yoo,
  • Shin-Wook Kang,
  • Kyu Hun Choi,
  • Hyeon Joo Jeong,
  • Dae-Suk Han,
  • Seung Hyeok Han

DOI
https://doi.org/10.1371/journal.pone.0101935
Journal volume & issue
Vol. 9, no. 7
p. e101935

Abstract

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BACKGROUND: Proteinuria is a target for renoprotection in kidney diseases. However, optimal level of proteinuria reduction in IgA nephropathy (IgAN) is unknown. METHODS: We conducted a retrospective observational study in 500 patients with biopsy-proven IgAN. Time-averaged proteinuria (TA-P) was calculated as the mean of every 6 month period of measurements of spot urine protein-to-creatinine ratio. The study endpoints were a 50% decline in estimated glomerular filtration rate (eGFR), onset of end-stage renal disease (ESRD), and slope of eGFR. RESULTS: During a median follow-up duration of 65 (12-154) months, a 50% decline in eGFR occurred in 1 (0.8%) patient with TA-P of <0.3 g/g compared to 6 (2.7%) patients with TA-P of 0.3-0.99 g/g (hazard ratio, 2.82; P = 0.35). Risk of reaching a 50% decline in eGFR markedly increased in patients with TA-P of 1.0-2.99 g/g (P = 0.002) and those with TA-P≥3.0 g/g (P<0.001). ESRD did not occur in patients with TA-P<1.0 g/g compared to 26 (20.0%) and 8 (57.1%) patients with TA-P of 1.0-2.99 and ≥3.0 g/g, respectively. Kidney function of these two groups deteriorated faster than those with TA-P<1.0 g/g (P<0.001). However, patients with TA-P of 0.3-0.99 g/g had a greater decline of eGFR than patients with TA-P<0.3 g/g (-0.41±1.68 vs. -0.73±2.82 ml/min/1.73 m2/year, P = 0.03). CONCLUSION: In this study, patients with TA-P<1.0 g/g show favorable outcomes. However, given the faster eGFR decline in patients with TA-P of 0.3-0.99 g/g than in patients with TA-P<0.3 g/g, the ultimate optimal goal of proteinuria reduction can be lowered in the management of IgAN.