title: Renal replacement therapy for rare diseases affecting the kidney: an analysis of the ERA-EDTA Registry.
abstract: BACKGROUND
  In recent years, increased efforts have been undertaken to address the needs of patients with rare diseases by international initiatives and consortia devoted to rare disease research and management. However, information on the overall prevalence of rare diseases within the end-stage renal disease (ESRD) population is limited. The aims of this study were (i) to identify those rare diseases within the ERA-EDTA Registry for which renal replacement therapy (RRT) is being provided and (ii) to determine the prevalence and incidence of RRT for ESRD due to rare diseases, both overall and separately for children and adults.
  
  
  METHODS
  The Orphanet classification of rare disease was searched for rare diseases potentially causing ESRD, and these diagnosis codes were mapped to the corresponding ERA-EDTA primary renal disease codes. Thirty-one diagnoses were defined as rare diseases causing ESRD.
  
  
  RESULTS
  From 1 January 2007 to 31 December 2011, 7194 patients started RRT for a rare disease (10.6% children). While some diseases were exclusively found in adults (e.g. Fabry disease), primary oxalosis, cystinosis, congenital anomalies of the kidney and urinary tract (CAKUT) and medullary cystic kidney disease affected young patients in up to 46%. On 31 December 2011, 20 595 patients (12.4% of the total RRT population) were on RRT for ESRD caused by a rare disease. The point prevalence was 32.5 per million age-related population in children and 152.0 in adults. Only 5.8% of these patients were younger than 20 years; however, 57.7% of all children on RRT had a rare disease, compared with only 11.9% in adults. CAKUT and focal segmental glomerulosclerosis were the most prevalent rare disease entities among patients on RRT.
  
  
  CONCLUSIONS
  More than half of all children and one of nine adults on RRT in the ERA-EDTA Registry suffer from kidney failure due to a rare disease, potentially with a large number of additional undiagnosed or miscoded cases. Comprehensive diagnostic assessment and the application of accurate disease classification systems are essential for improving the identification and management of patients with rare kidney diseases.
authors.affiliation: Division of Pediatric Nephrology, Center for Pediatrics and Adolescent Medicine, Heidelberg, Germany.
authors.forename: Elke
authors.initials: E
authors.lastname: Wühl
authors.affiliation: ERA-EDTA Registry and ESPN/ERA-EDTA Registry, Department of Medical Informatics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Karlijn J
authors.initials: KJ
authors.lastname: van Stralen
authors.affiliation: Department of Internal Medicine I, Division of Nephrology, University of Würzburg, Würzburg, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Wanner
authors.affiliation: Servicio de Nefrología Pediátrica y Hemodiálisis, Hospital Universitario Materno-Infantil Vall d'Hebron, Barcelona, Spain.
authors.forename: Gema
authors.initials: G
authors.lastname: Ariceta
authors.affiliation: Department of Nephrology, Copenhagen University Hospital at Herlev, Herlev, Denmark.
authors.forename: James Goya
authors.initials: JG
authors.lastname: Heaf
authors.affiliation: Department of Pediatrics, Oslo University Hospital, Rikshospitalet, Oslo, Norway.
authors.forename: Anna K
authors.initials: AK
authors.lastname: Bjerre
authors.affiliation: Division of Nephrology, Landspitali-The National University Hospital of Iceland, Reykjavik, Iceland Faculty of Medicine, School of Health Sciences, University of Iceland, Reykjavik, Iceland.
authors.forename: Runolfur
authors.initials: R
authors.lastname: Palsson
authors.affiliation: Service de Néphrologie Transplantation Dialyse, Centre Hospitalier Universitaire de Bordeaux, Bordeaux, France.
authors.forename: Gabrielle
authors.initials: G
authors.lastname: Duneau
authors.affiliation: Department of Nephrology, Radboud University Medical Centre Nijmegen, Nijmegen, The Netherlands.
authors.forename: Andries J
authors.initials: AJ
authors.lastname: Hoitsma
authors.affiliation: Department of Community Health Sciences, Faculty of Medicine, University of Calgary, Calgary, Alberta, Canada.
authors.forename: Pietro
authors.initials: P
authors.lastname: Ravani
authors.affiliation: Division of Pediatric Nephrology, Center for Pediatrics and Adolescent Medicine, Heidelberg, Germany.
authors.forename: Franz
authors.initials: F
authors.lastname: Schaefer
authors.affiliation: ERA-EDTA Registry and ESPN/ERA-EDTA Registry, Department of Medical Informatics, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
authors.forename: Kitty J
authors.initials: KJ
authors.lastname: Jager
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D002675:Child, Preschool; D005060:Europe / Q000453:epidemiology; D005260:Female; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D007676:Kidney Failure, Chronic / Q000453:epidemiology / Q000209:etiology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D035583:Rare Diseases / Q000150:complications*; D012042:Registries / Q000706:statistics & numerical data*; D017582:Renal Replacement Therapy; D013997:Time Factors; D055815:Young Adult
keywords: incidence; orphan disease; prevalence; rare disease; renal replacement therapy