title: Risk factors in familial osteoarthritis: the GARP sibling study.
abstract: OBJECTIVE
  To investigate the association between systemic and local risk factors and familial osteoarthritis (OA) at multiple sites.
  
  
  METHODS
  Patients and their siblings had primary OA at multiple sites at middle age. OA diagnosis followed the American College of Rheumatology criteria. We recruited 345 controls (mean age 57 years (range 40-76), 64% women) by random sampling from the population by telephone and collected all data by questionnaires. Odds ratios (ORs) were adjusted for sex, age and body mass index (BMI) (kg/m(2)), 95% confidence intervals (CIs95) were computed using robust standard errors with the intra-family effect taken into account.
  
  
  RESULTS
  Three hundred and eighty-two patients (mean age 60 years [range 43-79]), 82% women had OA in the spine (80%), hands (72%), knees (34%) and hips (24%). In women, an association of familial OA with a young age at natural menopause (<45 years), OR=2.6 (CI95 1.5-4.5) was found. Physically demanding jobs led to an increased risk of familial OA in men: OR=2.6 (CI95 1.3-5.3). Familial OA was more prevalent in individuals with a BMI>30, OR=2.0 (CI95 1.3-3.2) compared to a BMI of <25. Taller persons had a lower risk of familial OA, OR=0.33 (0.1-0.8) in the height category >180 cm relative to a height of <160 cm. A history of meniscectomy, increased the risk of familial OA at multiple sites with knee involvement, OR=6.2 (CI95 3.0-12.7).
  
  
  CONCLUSIONS
  Systemic and local risk factors play a role in the etiology of familial OA at multiple sites.
authors.affiliation: Leiden University Medical Center, Department of Rheumatology, The Netherlands. N.Riyazi@lumc.nl
authors.forename: N
authors.initials: N
authors.lastname: Riyazi
authors.forename: F R
authors.initials: FR
authors.lastname: Rosendaal
authors.forename: E
authors.initials: E
authors.lastname: Slagboom
authors.forename: H M
authors.initials: HM
authors.lastname: Kroon
authors.forename: F C
authors.initials: FC
authors.lastname: Breedveld
authors.forename: M
authors.initials: M
authors.lastname: Kloppenburg
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D004522:Educational Status; D005260:Female; D020022:Genetic Predisposition to Disease; D050823:Hand Joints; D006801:Humans; D008297:Male; D017533:Marital Status; D008593:Menopause; D008875:Middle Aged; D009765:Obesity / Q000150:complications; D009784:Occupational Diseases / Q000209:etiology / Q000235:genetics; D010003:Osteoarthritis / Q000209:etiology* / Q000235:genetics; D015207:Osteoarthritis, Hip / Q000209:etiology / Q000235:genetics; D020370:Osteoarthritis, Knee / Q000209:etiology / Q000235:genetics; D012307:Risk Factors; D013122:Spinal Diseases / Q000209:etiology / Q000235:genetics