Revisiting arthritis prevalence projections--it's more than just the aging of the population.

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.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.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.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.