title: Familial clustering of ESRD in the Norwegian population.
abstract: OBJECTIVE
  Studies and clinical experience suggest that kidney disease clusters in families, but few population-based studies have been performed. This study investigates risks and causes of ESRD in Norwegians with and without a first-degree relative with ESRD.
  
  
  METHODS
  On the basis of data from the Norwegian Population Registry, first-degree relatives for most Norwegians were identified. All Norwegians with ESRD (defined as chronic RRT) since 1980 have been registered in the Norwegian Renal Registry. All Norwegians born in Norway who were alive in 1980 and had at least one registered relative were included. For this study, data on ESRD were available through 2009, and individuals without ESRD were censored at December 31, 2009. Data were analyzed in a cohort design, with ESRD in a first-degree relative of the included person as the main explanatory variable. Risks of ESRD and different causes of ESRD were analyzed using Cox regression statistics.
  
  
  RESULTS
  In total, 5,119,134 individuals were included, of whom 8203 individuals developed ESRD during follow-up and 27,046 individuals had a first-degree relative with ESRD. Compared with individuals without a first-degree relative with ESRD, individuals with a first-degree relative with ESRD had a relative risk of ESRD of 7.2 (95% confidence interval, 6.5 to 8.1). Similar analyses showed that relative risk of ESRD caused by nonhereditary causes was 3.7 (95% confidence interval, 3.1 to 4.4), relative risk of ESRD caused by glomerular disease was 5.2 (95% confidence interval, 4.1 to 6.6), relative risk of ESRD caused by interstitial disease was 4.7 (95% confidence interval, 3.1 to 7.3), relative risk of ESRD caused by diabetic nephropathy was 2.6 (95% confidence interval, 1.6 to 4.1), and relative risk of ESRD caused by hypertensive nephrosclerosis was 2.6 (95% confidence interval, 1.6 to 4.1). Relative risk of nonhereditary parenchymal renal disease was 3.8 (95% confidence interval, 3.1 to 4.7).
  
  
  CONCLUSIONS
  As expected, ESRD clusters in families. Interestingly, ESRD without known hereditary cause also clusters in families.
authors.affiliation: Department of Medicine, Haukeland University Hospital, Bergen, Norway; rannveig.skrunes@helse-bergen.no.
authors.forename: Rannveig
authors.initials: R
authors.lastname: Skrunes
authors.affiliation: Department of Medicine, Haukeland University Hospital, Bergen, Norway; Department of Clinical Medicine, University of Bergen, Bergen, Norway;
authors.forename: Einar
authors.initials: E
authors.lastname: Svarstad
authors.affiliation: Department of Transplantation Medicine, Rikshospitalet, Oslo University Hospital, Oslo, Norway; and.
authors.forename: Anna Varberg
authors.initials: AV
authors.lastname: Reisæter
authors.affiliation: Department of Clinical Medicine, University of Bergen, Bergen, Norway; Department of Medicine, Haugesund Hospital, Haugesund, Norway.
authors.forename: Bjørn Egil
authors.initials: BE
authors.lastname: Vikse
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D016000:Cluster Analysis; D005260:Female; D020022:Genetic Predisposition to Disease; D040941:Heredity; D006801:Humans; D007676:Kidney Failure, Chronic / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D010375:Pedigree; D010641:Phenotype; D016016:Proportional Hazards Models; D012042:Registries; D018570:Risk Assessment; D012307:Risk Factors; D013997:Time Factors; D055815:Young Adult
keywords: ESRD; family history; nephrology
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