title: Optimal proteinuria target for renoprotection in patients with IgA nephropathy.
abstract: 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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: Division of Nephrology, Department of Internal Medicine, College of Medicine, Yonsei University, Seoul, Republic of Korea.
authors.forename: Ki Heon
authors.initials: KH
authors.lastname: Nam
authors.affiliation: Department of Pathology, NHIS Ilsan Hospital, Goyang-shi, Gyeonggi-do, Republic of Korea.
authors.forename: Jeong Hae
authors.initials: JH
authors.lastname: Kie
authors.affiliation: Division of Nephrology, Department of Internal Medicine, College of Medicine, Yonsei University, Seoul, Republic of Korea.
authors.forename: Mi Jung
authors.initials: MJ
authors.lastname: Lee
authors.affiliation: Department of Internal Medicine, NHIS Ilsan Hospital, Goyang-shi, Gyeonggi-do, Republic of Korea.
authors.forename: Tae-Ik
authors.initials: TI
authors.lastname: Chang
authors.affiliation: Department of Internal Medicine, NHIS Ilsan Hospital, Goyang-shi, Gyeonggi-do, Republic of Korea.
authors.forename: Ea Wha
authors.initials: EW
authors.lastname: Kang
authors.affiliation: Biostatistics Collaboration Unit, College of Medicine, Yonsei University, Seoul, Republic of Korea.
authors.forename: Dong Wook
authors.initials: DW
authors.lastname: Kim
authors.affiliation: Department of Pathology, College of Medicine, Yonsei University, Seoul, Republic of Korea.
authors.forename: Beom Jin
authors.initials: BJ
authors.lastname: Lim
authors.affiliation: Division of Nephrology, Department of Internal Medicine, College of Medicine, Yonsei University, Seoul, Republic of Korea.
authors.forename: Jung Tak
authors.initials: JT
authors.lastname: Park
authors.affiliation: Division of Nephrology, Department of Internal Medicine, College of Medicine, Yonsei University, Seoul, Republic of Korea.
authors.forename: Young Eun
authors.initials: YE
authors.lastname: Kwon
authors.affiliation: Division of Nephrology, Department of Internal Medicine, College of Medicine, Yonsei University, Seoul, Republic of Korea.
authors.forename: Yung Ly
authors.initials: YL
authors.lastname: Kim
authors.affiliation: Division of Nephrology, Department of Internal Medicine, College of Medicine, Yonsei University, Seoul, Republic of Korea.
authors.forename: Kyoung Sook
authors.initials: KS
authors.lastname: Park
authors.affiliation: Division of Nephrology, Department of Internal Medicine, College of Medicine, Yonsei University, Seoul, Republic of Korea.
authors.forename: Seong Yeong
authors.initials: SY
authors.lastname: An
authors.affiliation: Division of Nephrology, Department of Internal Medicine, College of Medicine, Yonsei University, Seoul, Republic of Korea.
authors.forename: Hyung Jung
authors.initials: HJ
authors.lastname: Oh
authors.affiliation: Division of Nephrology, Department of Internal Medicine, College of Medicine, Yonsei University, Seoul, Republic of Korea.
authors.forename: Tae-Hyun
authors.initials: TH
authors.lastname: Yoo
authors.affiliation: Division of Nephrology, Department of Internal Medicine, College of Medicine, Yonsei University, Seoul, Republic of Korea; Severance Biomedical Science Institute, Brain Korea 21, Yonsei University, Seoul, Republic of Korea.
authors.forename: Shin-Wook
authors.initials: SW
authors.lastname: Kang
authors.affiliation: Division of Nephrology, Department of Internal Medicine, College of Medicine, Yonsei University, Seoul, Republic of Korea.
authors.forename: Kyu Hun
authors.initials: KH
authors.lastname: Choi
authors.affiliation: Department of Pathology, College of Medicine, Yonsei University, Seoul, Republic of Korea.
authors.forename: Hyeon Joo
authors.initials: HJ
authors.lastname: Jeong
authors.affiliation: Division of Nephrology, Department of Internal Medicine, College of Medicine, Yonsei University, Seoul, Republic of Korea.
authors.forename: Dae-Suk
authors.initials: DS
authors.lastname: Han
authors.affiliation: Division of Nephrology, Department of Internal Medicine, College of Medicine, Yonsei University, Seoul, Republic of Korea.
authors.forename: Seung Hyeok
authors.initials: SH
authors.lastname: Han
mesh_terms: D000328:Adult; D005260:Female; D005919:Glomerular Filtration Rate; D005922:Glomerulonephritis, IGA / Q000401:mortality / Q000628:therapy / Q000652:urine*; D006801:Humans; D053208:Kaplan-Meier Estimate; D007668:Kidney / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D016016:Proportional Hazards Models; D011507:Proteinuria / Q000401:mortality / Q000628:therapy / Q000652:urine*; D012189:Retrospective Studies; D016896:Treatment Outcome; D055815:Young Adult