title: Influence of familial factors on radiologic disease progression over two years in siblings with osteoarthritis at multiple sites: a prospective longitudinal cohort study.
abstract: OBJECTIVE
  The contribution of genetics to osteoarthritis (OA) progression is not known. To gain more insight into whether familial factors play a role in disease progression of OA, we analyzed familial aggregation of radiologic OA progression in a study of sibling pairs (the Genetics, Arthrosis, and Progression [GARP] study).
  
  
  METHODS
  A total of 105 white probands and their 105 siblings with OA at multiple joint sites were included in a prospective cohort study. Radiologic progression of OA was defined as a 1-point score increase in total scores for severity of joint space narrowing (JSN) or osteophytes on standardized radiographs of the hands, knees, and hips obtained at baseline and after 2 years. Odds ratios were calculated for siblings and probands sharing radiologic disease progression.
  
  
  RESULTS
  A total of 100 probands and 93 siblings were followed for 2 years (median age 60 years, 80% women). In 92 sibling pairs both the proband and sibling had complete radiographic followup. Radiologic progression of JSN and osteophytes was present in 47% and 42% of the probands and 34% and 37% of the siblings, respectively. The odds ratios (95% confidence intervals), adjusted for age, sex, and body mass index, of a sibling having radiologic progression if the proband had progression were 3.0 (1.2-7.8) for JSN progression and 1.5 (0.6-3.6) for osteophyte progression. A dose-response relationship was found between the amount of increase in JSN total scores among probands and the progression of JSN in siblings.
  
  
  CONCLUSIONS
  Familial factors played a role in the radiologic progression of JSN over 2 years in patients with OA at multiple sites.
authors.affiliation: Leiden University Medical Center, Leiden, The Netherlands.
authors.forename: Stella A
authors.initials: SA
authors.lastname: Botha-Scheepers
authors.forename: Iain
authors.initials: I
authors.lastname: Watt
authors.forename: Eline
authors.initials: E
authors.lastname: Slagboom
authors.forename: Ingrid
authors.initials: I
authors.lastname: Meulenbelt
authors.forename: Frits R
authors.initials: FR
authors.lastname: Rosendaal
authors.forename: Ferdinand C
authors.initials: FC
authors.lastname: Breedveld
authors.forename: Margreet
authors.initials: M
authors.lastname: Kloppenburg
mesh_terms: D000368:Aged; D001175:Arthrography; D018450:Disease Progression; D005192:Family Health; D005260:Female; D005500:Follow-Up Studies; D050823:Hand Joints / Q000000981:diagnostic imaging; D006621:Hip Joint / Q000000981:diagnostic imaging; D006801:Humans; D007719:Knee Joint / Q000000981:diagnostic imaging; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000235:genetics; D020370:Osteoarthritis, Knee / Q000000981:diagnostic imaging / Q000453:epidemiology / Q000235:genetics; D012307:Risk Factors; D012720:Severity of Illness Index; D035781:Siblings