title: Revisiting arthritis prevalence projections--it's more than just the aging of the population.
abstract: OBJECTIVE
  Data for successive population surveys show there is a sustained increase in the prevalence of arthritis, surpassing projected estimates. We examined whether the often-made assumption of stability in age/sex-specific arthritis point-prevalence estimates when estimating future burden is upheld; we used nearly a decade of survey data, and computed new projections for arthritis prevalence in Canada, taking into account past changes in age/sex-specific prevalence estimates and anticipated changes in the age/sex structure of the population. The prevalence from 1994 to 2003, overall and by age and sex, was documented.
  
  
  METHODS
  Analyses were based on persons aged 15+ years from 3 cycles of the National Population Health Survey (1994-99; n > 14,000) and 2 cycles of the Canadian Community Health Survey (2000-03; n > 130,000). Two projection scenarios were adopted to estimate future burden.
  
  
  RESULTS
  Stability in age/sex point-prevalence estimates was not observed. From 1994 to 2003, absolute and relative increases were greatest in the older age groups (55+ yrs) and younger age groups (25-54 yrs), respectively. By 2021, we anticipate the prevalence of arthritis in Canada will have increased to between 21% and 26%. Overall, the prevalence increased from 13.4% to 17.6% from 1994 to 2003, an increase of nearly 50% in the number of Canadians reporting arthritis.
  
  
  CONCLUSIONS
  The assumption of stable age/sex prevalence estimates over time does not hold in Canada. Past projections have underestimated future burden; past trends need to be considered.
authors.affiliation: Arthritis Community Research and Evaluation Unit, Toronto Western Research Institute, University Health Network, Toronto, Ontario, Canada.
authors.forename: Anthony V
authors.initials: AV
authors.lastname: Perruccio
authors.forename: J Denise
authors.initials: JD
authors.lastname: Power
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Badley
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001168:Arthritis / Q000453:epidemiology*; D002170:Canada / Q000453:epidemiology; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D016016:Proportional Hazards Models; D015203:Reproducibility of Results; D018570:Risk Assessment / Q000379:methods*; D012307:Risk Factors; D012680:Sensitivity and Specificity; D017678:Sex Distribution