title: Predicting the outcome of chronic kidney disease by the estimated nephron number: the rationale and design of PRONEP, a prospective, multicenter, observational cohort study.
abstract: BACKGROUND
  The nephron number is thought to be associated with the outcome of chronic kidney disease (CKD). If the nephron number can be estimated in the clinical setting, it could become a strong tool to predict renal outcome. This study was designed to estimate the nephron number in CKD patients and to establish a method to predict the outcome by using the estimated nephron number.
  
  
  METHODS
  The hypothesis of this study is that the estimated nephron number can predict the outcome of a CKD patient. This will be a multicenter, prospective (minimum 3 and maximum 5 years follow-up) study. The subjects will comprise CKD patients aged over 14 years who have undergone a kidney biopsy. From January 2011 to March 2013, we will recruit 600 CKD patients from 10 hospitals belonging to the National Hospital Organization of Japan. The primary parameter for assessment is the composite of total mortality, renal death, cerebro-cardiovascular events, and a 50% reduction in the eGFR. The secondary parameter is the rate of eGFR decline per year. The nephron number will be estimated by the glomerular density in biopsy specimens and the renal cortex volume. This study includes one sub-cohort study to establish the equation to calculate the renal cortex volume. Enrollment will be performed at the time of the kidney biopsy, and the data will consist of a medical interview, ultrasound for measurement of the kidney size, blood or urine test, and the pathological findings of the kidney biopsy. Patients will continue to have medical consultations and receive examinations and/or treatment as usual. The data from the patients will be collected once a year after the kidney biopsy until March 2016. All data using this study are easily obtained in routine clinical practice.
  
  
  CONCLUSIONS
  This study includes the first trials to estimate the renal cortex volume and nephron number in the general clinical setting. Furthermore, this is the first prospective study to examine whether the nephron number predicts the outcome of CKD patients. The results from this study should provide powerful new tools for nephrologists in routine clinical practice.
  
  
  BACKGROUND
  UMIN-Clinical Trial Registration, UMIN000004784.
authors.affiliation: National Hospital Organization Chiba-East Hospital, Chiba, Japan. imasawa@cehpnet.com
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Imasawa
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakazato
authors.forename: Hiroo
authors.initials: H
authors.lastname: Ikehira
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Fujikawa
authors.forename: Ryo
authors.initials: R
authors.lastname: Nakajima
authors.forename: Takahito
authors.initials: T
authors.lastname: Ito
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Ando
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Yoshimura
authors.forename: Masaru
authors.initials: M
authors.lastname: Nakayama
authors.forename: Kensei
authors.initials: K
authors.lastname: Yahata
authors.forename: Osamu
authors.initials: O
authors.lastname: Sasaki
authors.forename: Takaaki
authors.initials: T
authors.lastname: Yaomura
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Katafuchi
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Yamamura
authors.forename: Takehiko
authors.initials: T
authors.lastname: Kawaguchi
authors.forename: Motonobu
authors.initials: M
authors.lastname: Nishimura
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kitamura
authors.forename: Takashi
authors.initials: T
authors.lastname: Kenmochi
authors.forename: Akira
authors.initials: A
authors.lastname: Shimatsu
mesh_terms: D000293:Adolescent; D000328:Adult; D001706:Biopsy; D002452:Cell Count; D002908:Chronic Disease; D005260:Female; D006801:Humans; D007672:Kidney Cortex / Q000000981:diagnostic imaging / Q000473:pathology*; D007674:Kidney Diseases / Q000000981:diagnostic imaging / Q000473:pathology*; D008297:Male; D055641:Mathematical Concepts; D009399:Nephrons / Q000473:pathology*; D009929:Organ Size; D011237:Predictive Value of Tests; D012107:Research Design; D014463:Ultrasonography; D055815:Young Adult