Rising obesity is driving an increase in arthritis prevalence, and the association is not appreciated because the impact of body mass index on joint disease is not fully understood, according to a study spanning four generations.
The proportion of people in more recent birth cohorts reporting arthritis symptoms indicates a successively greater prevalence of arthritis compared to earlier generations, based on an 18-year longitudinal study conducted by Elizabeth M. Badley, PhD, of Dalla Lana School of Public Health, University of Toronto, and her colleagues. The researchers compared the prevalence of arthritis across four birth cohorts: World War II (1935-1944; n = 1,598), older baby boomers (1945-1954; n = 2,208), younger baby boomers (1955-1964; n = 2,781) and Generation Xers (1965-1974; n = 2,230).
“Although our results do not represent projections as such, extrapolation of the trajectories of arthritis with age and comparison of the trajectories across cohorts suggest that current projections of the prevalence of arthritis … may be too low for obese individuals,” they concluded.
Using the World War II cohort as the reference group for comparison, the odds ratio for arthritis in Gen Xers was 3.2; for younger baby boomers it was 2.14; for older baby boomers, it was 1.48.
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Furthermore, in all cohorts the age of onset of arthritis in obese individuals was earlier compared to those of normal weight.
“This has implications for the targeting of public health messages for the control and management of arthritis,” the researchers wrote (Arthritis Care Res. 2017. doi: 10.1002/acr.23213).
The authors noted that although the study participants were asked about arthritis in general it was likely the overall findings reflected an increasing prevalence of osteoarthritis.
And while the researchers could only speculate about the reasons for the higher prevalence of arthritis seen in recent cohorts, it was possible there had been “unrecognized changes over time in environmental or biologic exposures.”
The study was funded in part by a CIHR operating grant. No conflicts of interest were declared.