title: Multinational Assessment of Accuracy of Equations for Predicting Risk of Kidney Failure: A Meta-analysis.
abstract: OBJECTIVE
  Identifying patients at risk of chronic kidney disease (CKD) progression may facilitate more optimal nephrology care. Kidney failure risk equations, including such factors as age, sex, estimated glomerular filtration rate, and calcium and phosphate concentrations, were previously developed and validated in 2 Canadian cohorts. Validation in other regions and in CKD populations not under the care of a nephrologist is needed.
  
  
  OBJECTIVE
  To evaluate the accuracy of the risk equations across different geographic regions and patient populations through individual participant data meta-analysis.
  
  
  METHODS
  Thirty-one cohorts, including 721,357 participants with CKD stages 3 to 5 in more than 30 countries spanning 4 continents, were studied. These cohorts collected data from 1982 through 2014.
  
  
  METHODS
  Cohorts participating in the CKD Prognosis Consortium with data on end-stage renal disease.
  
  
  METHODS
  Data were obtained and statistical analyses were performed between July 2012 and June 2015. Using the risk factors from the original risk equations, cohort-specific hazard ratios were estimated and combined using random-effects meta-analysis to form new pooled kidney failure risk equations. Original and pooled kidney failure risk equation performance was compared, and the need for regional calibration factors was assessed.
  
  
  METHODS
  Kidney failure (treatment by dialysis or kidney transplant).
  
  
  RESULTS
  During a median follow-up of 4 years of 721,357 participants with CKD, 23,829 cases kidney failure were observed. The original risk equations achieved excellent discrimination (ability to differentiate those who developed kidney failure from those who did not) across all cohorts (overall C statistic, 0.90; 95% CI, 0.89-0.92 at 2 years; C statistic at 5 years, 0.88; 95% CI, 0.86-0.90); discrimination in subgroups by age, race, and diabetes status was similar. There was no improvement with the pooled equations. Calibration (the difference between observed and predicted risk) was adequate in North American cohorts, but the original risk equations overestimated risk in some non-North American cohorts. Addition of a calibration factor that lowered the baseline risk by 32.9% at 2 years and 16.5% at 5 years improved the calibration in 12 of 15 and 10 of 13 non-North American cohorts at 2 and 5 years, respectively (P = .04 and P = .02).
  
  
  CONCLUSIONS
  Kidney failure risk equations developed in a Canadian population showed high discrimination and adequate calibration when validated in 31 multinational cohorts. However, in some regions the addition of a calibration factor may be necessary.
authors.affiliation: Department of Medicine, Seven Oaks General Hospital, University of Manitoba, Winnipeg, Canada2Department of Community Health Sciences, Seven Oaks General Hospital, University of Manitoba, Winnipeg, Canada.
authors.forename: Navdeep
authors.initials: N
authors.lastname: Tangri
authors.affiliation: Johns Hopkins Medical Institutions, Baltimore, Maryland.
authors.forename: Morgan E
authors.initials: ME
authors.lastname: Grams
authors.affiliation: Division of Nephrology at Tufts Medical Center, Boston, Massachusetts.
authors.forename: Andrew S
authors.initials: AS
authors.lastname: Levey
authors.affiliation: Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
authors.forename: Josef
authors.initials: J
authors.lastname: Coresh
authors.affiliation: Johns Hopkins Medical Institutions, Baltimore, Maryland5Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
authors.forename: Lawrence J
authors.initials: LJ
authors.lastname: Appel
authors.affiliation: Department of Medicine, University of Wisconsin School of Medicine and Public Health, Madison7Department of Population Health Sciences, University of Wisconsin School of Medicine and Public Health, Madison.
authors.forename: Brad C
authors.initials: BC
authors.lastname: Astor
authors.affiliation: Medical Division, Maccabi Healthcare Services, and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel.
authors.forename: Gabriel
authors.initials: G
authors.lastname: Chodick
authors.affiliation: Chronic Disease Research Group, Minneapolis Medical Research Foundation, Minneapolis, Minnesota10Department of Medicine, University of Minnesota, Minneapolis.
authors.forename: Allan J
authors.initials: AJ
authors.lastname: Collins
authors.affiliation: Department of Measurement & Reporting, Provincial Health Service Authority, Vancouver, British Columbia, Canada.
authors.forename: Ognjenka
authors.initials: O
authors.lastname: Djurdjev
authors.affiliation: Department of General Practice and Primary Health Care, School of Population Health, University of Auckland, Auckland, New Zealand.
authors.forename: C Raina
authors.initials: CR
authors.lastname: Elley
authors.affiliation: Division of Renal Medicine, CLINTEC, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Marie
authors.initials: M
authors.lastname: Evans
authors.affiliation: Departments of Medicine and Epidemiology and Biostatistics, Western University, and Institute for Clinical Evaluative Sciences, Ontario, Canada.
authors.forename: Amit X
authors.initials: AX
authors.lastname: Garg
authors.affiliation: Department of Cancer Research and Molecular Medicine, Faculty of Medicine, Norwegian University of Science Technology, Trondheim16Division of Nephrology, Department of Medicine, St Olav University Hospital, Trondheim, Norway.
authors.forename: Stein I
authors.initials: SI
authors.lastname: Hallan
authors.affiliation: Division of Nephrology at Tufts Medical Center, Boston, Massachusetts.
authors.forename: Lesley A
authors.initials: LA
authors.lastname: Inker
authors.affiliation: Division of Nephrology, Endocrinology and Vascular Medicine, Department of Medicine, Tohoku University School of Medicine, Sendai, Japan.
authors.forename: Sadayoshi
authors.initials: S
authors.lastname: Ito
authors.affiliation: Department of Epidemiology and Health Promotion, Institute for Health Promotion, Graduate School of Public Health, Yonsei University, Seoul, Korea.
authors.forename: Sun Ha
authors.initials: SH
authors.lastname: Jee
authors.affiliation: Memphis Veterans Affairs Medical Center, Memphis, Tennessee20University of Tennessee Health Science Center, Memphis, Tennessee.
authors.forename: Csaba P
authors.initials: CP
authors.lastname: Kovesdy
authors.affiliation: Department of Medical Genetics, Molecular and Clinical Pharmacology, Division of Genetic Epidemiology, Medical University of Innsbruck, Innsbruck, Austria.
authors.forename: Florian
authors.initials: F
authors.lastname: Kronenberg
authors.affiliation: Department of Clinical Pharmacy and Pharmacology, University of Groningen, University Medical Center Groningen, the Netherlands.
authors.forename: Hiddo J Lambers
authors.initials: HJ
authors.lastname: Heerspink
authors.affiliation: Division of Applied Health Sciences, University of Aberdeen, and NHS Grampian, Foresterhill, Aberdeen, Scotland.
authors.forename: Angharad
authors.initials: A
authors.lastname: Marks
authors.affiliation: Division of Nephrology, Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, New York.
authors.forename: Girish N
authors.initials: GN
authors.lastname: Nadkarni
authors.affiliation: Division of Nephrology and Hypertension, Cleveland Clinic, Cleveland, Ohio.
authors.forename: Sankar D
authors.initials: SD
authors.lastname: Navaneethan
authors.affiliation: National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona.
authors.forename: Robert G
authors.initials: RG
authors.lastname: Nelson
authors.affiliation: Department of Nephrology and Hypertension, University of Erlangen-Nürnberg, Erlangen, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Titze
authors.affiliation: Division of Nephrology at Tufts Medical Center, Boston, Massachusetts.
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Sarnak
authors.affiliation: CESP, INSERM, Villejuif, France29Université Paris-Saclay, Université Paris-Sud, UVSQ, Villejuif, France.
authors.forename: Benedicte
authors.initials: B
authors.lastname: Stengel
authors.affiliation: Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland30The George Institute for Global Health, Nuffield Department of Population Health, University of Oxford, Oxford, England31The George Institute for Global Health, University of Sydney, Sy.
authors.forename: Mark
authors.initials: M
authors.lastname: Woodward
authors.affiliation: Dialysis Unit, University Hospital of the Ryukyus, Nishihara, Okinawa, Japan.
authors.forename: Kunitoshi
authors.initials: K
authors.lastname: Iseki
mesh_terms: D015331:Cohort Studies; D018450:Disease Progression; D006801:Humans; D011379:Prognosis; D016016:Proportional Hazards Models; D051437:Renal Insufficiency / Q000453:epidemiology*; D051436:Renal Insufficiency, Chronic / Q000150:complications*; D018570:Risk Assessment