title: Parental rheumatoid arthritis and long-term child morbidity: a nationwide cohort study.
abstract: To estimate the influence of parental rheumatoid arthritis (RA) on child morbidity.
  
  
  
  Nationwide cohort study.
  
  
  
  Individual linkage to nationwide Danish registries.
  
  
  
  All singletons born in Denmark during 1977-2008 (n=1 917 723) were followed for an average of 16 years.
  
  
  
  Adjusted HRs for child morbidity; that is, 11 main diagnostic groups and specific autoimmune diseases within the International Classification of Diseases 8th and 10th versions.
  
  
  
  Compared with unexposed children, children exposed to maternal RA ('clinical' and 'preclinical') (n=13 566) had up to 26% higher morbidity in 8 of 11 main diagnostic groups. Similar tendencies were found in children exposed to paternal RA ('clinical' and 'preclinical') (n=6330), with statistically significantly higher morbidity in 6 of 11 diagnostic groups. HRs were highest for autoimmune diseases with up to three times increased risk of juvenile idiopathic arthritis (HR, 95% CI 3.30, 2.71 to 4.03 and 2.97, 2.20 to 4.01) and increased risk of up to 40% of diabetes mellitus type 1 (HR, 95% CI 1.37, 1.12 to 1.66 and 1.44, 1.09 to 1.90) and up to 30% increased HR of asthma (HR, 95% CI 1.28, 1.20 to 1.36 and 1.15, 1.04 to 1.26). Conclusions were roughly similar for children exposed to maternal clinical RA and for children only followed up to 16 years of age.
  
  
  
  Children of parents with RA had consistent excess morbidity. If the associations reflect biological mechanisms, genetic factors seem to play an important role. These findings call for attention given to children of parents with RA.
authors.affiliation: Research Unit Women's and Children's Health, The Juliane Marie Centre, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.
authors.forename: Ane Lilleøre
authors.initials: AL
authors.lastname: Rom
authors.affiliation: Section for Epidemiology, Department of Public Health, University of Aarhus, Aarhus, Denmark Research Unit of Gynecology and Obstetrics, Institute of Clinical Research, University of Southern Denmark, Odense, Denmark Department of Obstetrics and Gynecology, Odense University Hospital, Odense, Denmark.
authors.forename: Chun Sen
authors.initials: CS
authors.lastname: Wu
authors.affiliation: Department of Clinical Epidemiology, University of Aarhus, Aarhus, Denmark Department of Epidemiology, School of Public Health, University of California Los Angeles, Los Angeles, California, USA.
authors.forename: Jørn
authors.initials: J
authors.lastname: Olsen
authors.affiliation: Children's Hospital Oakland Research Institute, Oakland, California, USA.
authors.forename: Damini
authors.initials: D
authors.lastname: Jawaheer
authors.affiliation: Copenhagen Center for Arthritis Research, Center for Rheumatology and Spine Diseases, Rigshospitalet and Glostrup Hospital, Glostrup, Denmark Department of Clinical Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Copenhagen, Denmark.
authors.forename: Merete Lund
authors.initials: ML
authors.lastname: Hetland
authors.affiliation: Department of Obstetrics and Gynecology, The Juliane Marie Centre, Copenhagen University Hospital Rigshospitalet, Copenhagen, Denmark.
authors.forename: Bent
authors.initials: B
authors.lastname: Ottesen
authors.affiliation: Gynaecological Clinic, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark Virus, Lifestyle and Genes Unit, Danish Cancer Society Research Centre, Copenhagen, Denmark.
authors.forename: Lina Steinrud
authors.initials: LS
authors.lastname: Mørch
mesh_terms: D000293:Adolescent; D000328:Adult; D001172:Arthritis, Rheumatoid / Q000453:epidemiology* / Q000235:genetics*; D001327:Autoimmune Diseases / Q000453:epidemiology* / Q000235:genetics; D002648:Child; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D009017:Morbidity; D010290:Parents; D010375:Pedigree; D016016:Proportional Hazards Models; D012042:Registries; D012307:Risk Factors; D055815:Young Adult
keywords: Early Rheumatoid Arthritis; Epidemiology; Rheumatoid Arthritis