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Impact of obesity on arthritis prevalence may be underestimated
Projections of arthritis prevalence based only on the changing age of a population may underestimate future trends, according to findings published in Arthritis Care and Research.
Physicians and researchers likely underestimate the impact of BMI on arthritis, and more attention is needed to educate young and middle-aged adults about arthritis management, the researchers concluded.
“Arthritis is one of the most frequent chronic conditions with a prevalence that increases steeply with age,” Elizabeth M. Badley, DPhil, of the University of Toronto, and colleagues wrote. “A consequence of this, as population projections demonstrate, is that the prevalence of arthritis is expected to increase dramatically with the aging of the baby boomer population. ... Few studies have considered the possibility of cohort effects in arthritis prevalence, ie, that individuals born at different times may have a different prevalence of arthritis.”
To determine whether birth cohort effects in arthritis prevalence were associated with differences in risk factors over time, the researchers analyzed data collected biannually from the longitudinal Canadian National Population Health Survey from 1994 to 2011. They reviewed data from 8,817 patients across four birth cohorts: World War II, born from 1935 to 1944; older baby boomers, born from 1945 to 1954; younger baby boomers, born 1955 to 1964; and Generation X, born from 1965 to 1974.
The researchers reviewed data on self-reported arthritis diagnosed by a health professional and risk factors — including years of education, household income, smoking, physical activity, sedentary behavior and BMI — as well as the survey year. They then compared the age trajectory of arthritis by birth cohort using hierarchical age–period–cohort analyses.
According to the researchers, recent cohorts had a greater prevalence of arthritis, and the above risk factors were significantly associated with arthritis prevalence independent of cohort differences.
In addition, the effects of increasing education and income over time, which can potentially reduce arthritis prevalence, were nearly undone by the effects of increasing BMI. According to the researchers, significant cohort–BMI and age–BMI interactions suggested an earlier age of arthritis onset for obese individuals than those of normal weight.
“Not only was the cohort effect of higher arthritis prevalence more marked in those who were obese compared to those of normal weight, in all cohorts the age of onset of arthritis in obese individuals was earlier,” Badley and colleagues wrote. “This has implications for the targeting of public health messages for the control and management of arthritis.” – by Jason Laday
Disclosure: The researchers report grant support from a Canadian Institutes of Health Research.