title: Changes to osteoporosis prevalence according to method of risk assessment.
abstract: The impact of clinical risk factor-based absolute risk methods on the prevalence of high risk for osteoporotic fracture is unknown. We applied absolute risk methods to 6646 subjects and found that the prevalence of elderly women deemed to be at high risk increased substantially, whereas the overall prevalence was highly dependent on the threshold used to designate high risk.
  
  
  BACKGROUND
  Many groups have advocated using absolute risk methods that incorporate clinical risk factors to target patients for osteoporosis therapy. We examined how the application of such absolute risk classification systems influences the prevalence of those considered to be at high risk for osteoporotic fracture and compared these systems to one based solely on BMD.
  
  
  METHODS
  Using 6646 subjects from the Canadian Multicentre Osteoporosis Study (CaMos), a prospective, randomly selected, population-based cohort, we assessed three different systems for determining prevalence of high risk for osteoporotic fracture: a BMD-based system; a simplified risk factor system incorporating age, sex, BMD, and two clinical risk factors; and a comprehensive system, incorporating age, sex, BMD, and seven clinical risk factors. The 10-year absolute risks of incident fragility fracture were compared across systems using three different high-risk thresholds.
  
  
  RESULTS
  The prevalence of a T score < or = -2.5 was 18.8% (95% CI: 17.7-19.9%) in women and 3.9% (95% CI: 3.0-4.7%) in men. Using a 15% 10-year risk of fracture threshold, the prevalence of women at high risk increased to 46.9% (95% CI: 45.4-48.4) and 42.5% (95% CI: 41.1-43.9) when the comprehensive and simplified risk factor classification systems were used, respectively. Using a 25% 10-year absolute risk threshold, the prevalence of high risk was similar to that of the BMD-based system, whereas the 20% threshold gave intermediate rates. All thresholds analyzed resulted in an increased prevalence of older women at high risk for fracture, whereas only the 15% 10-year risk of fracture threshold resulted in an increase in the prevalence of men at high risk.
  
  
  CONCLUSIONS
  The application of risk factor-based systems results in an increased prevalence of older women at high risk. The prevalence of individuals at high risk may increase with changes to the methods used to determine those who are eligible for therapy. These data have important implications for the pattern of care and costs of treating osteoporotic fractures.
authors.affiliation: Department of Medicine, McGill University, Montreal, Quebec, Canada.
authors.forename: J Brent
authors.initials: JB
authors.lastname: Richards
authors.forename: William D
authors.initials: WD
authors.lastname: Leslie
authors.forename: Lawrence
authors.initials: L
authors.lastname: Joseph
authors.forename: Kerry
authors.initials: K
authors.lastname: Siminoski
authors.forename: David A
authors.initials: DA
authors.lastname: Hanley
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Adachi
authors.forename: Jacques P
authors.initials: JP
authors.lastname: Brown
authors.forename: Suzanne
authors.initials: S
authors.lastname: Morin
authors.forename: Alexandra
authors.initials: A
authors.lastname: Papaioannou
authors.forename: Robert G
authors.initials: RG
authors.lastname: Josse
authors.forename: Jerilynn C
authors.initials: JC
authors.lastname: Prior
authors.forename: K Shawn
authors.initials: KS
authors.lastname: Davison
authors.forename: Alan
authors.initials: A
authors.lastname: Tenenhouse
authors.forename: David
authors.initials: D
authors.lastname: Goltzman
mesh_terms: D015502:Absorptiometry, Photon; D015519:Bone Density; D002170:Canada / Q000453:epidemiology; D050723:Fractures, Bone / Q000453:epidemiology; D006801:Humans; D010024:Osteoporosis / Q000000981:diagnostic imaging / Q000453:epidemiology*; D015995:Prevalence; D011446:Prospective Studies; D018570:Risk Assessment