title: Risk factors for total hip replacement due to primary osteoarthritis: a cohort study in 50,034 persons.
abstract: OBJECTIVE
  To identify prospectively the possible risk factors for total hip replacement (THR) due to primary osteoarthritis in a large cohort.
  
  
  METHODS
  Data from a cardiovascular screening were matched with 9 years of national data on THR. Mean age at the start of followup was 54.9 years, and the 50,034 participants were followed up for an average of 9 years. During followup, 672 persons had a first THR due to primary osteoarthritis.
  
  
  RESULTS
  We found dose-response associations between body mass index (BMI), body weight, and the level of physical activity at work and THR for primary osteoarthritis. The highest versus the lowest quarter of BMI had a relative risk of 2.0 (95% confidence interval [95% CI] 1.4-2.9) among men and 3.0 (95% CI 2.1-4.1) among women. The highest versus the lowest quarter of body weight had a relative risk of 2.1 (95% CI 1.4-3.2) among men and 3.4 (95% CI 2.4-4.9) among women. Intensive versus sedentary physical activity at work had a relative risk of 2.1 (95% CI 1.5-3.0) among men and 2.1 (95% CI 1.3-3.3) among women. No association was found between physical activity in leisure and THR for primary osteoarthritis.
  
  
  CONCLUSIONS
  Intensive physical activity at work and a high BMI each contribute significantly to the overall risk of undergoing THR due to primary osteoarthritis. Lowering the exposure to these risk factors may substantially reduce the need for hip replacement.
authors.affiliation: Orthopaedic University Clinic, Ullevål Hospital, Oslo, Norway. Gunnar.Flugsrud@ioks.uio.no
authors.forename: Gunnar B
authors.initials: GB
authors.lastname: Flugsrud
authors.forename: Lars
authors.initials: L
authors.lastname: Nordsletten
authors.forename: Birgitte
authors.initials: B
authors.lastname: Espehaug
authors.forename: Leif I
authors.initials: LI
authors.lastname: Havelin
authors.forename: Haakon E
authors.initials: HE
authors.lastname: Meyer
mesh_terms: D000328:Adult; D000368:Aged; D019644:Arthroplasty, Replacement, Hip; D015992:Body Mass Index; D001835:Body Weight; D015331:Cohort Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000601:surgery*; D005082:Physical Exertion; D012307:Risk Factors; D014937:Work