Both obesity and weight loss are associated with worsening disability from rheumatoid arthritis, new research suggests.
An analysis of data from two long-term clinical registries involving a total of 25,020 patients with rheumatoid arthritis and 62,484 person-years of follow-up revealed that severely obese individuals with RA had significantly higher Health Assessment Questionnaire or Multi-Dimensional-HAQ scores at enrollment, compared with overweight participants, even after adjusting for confounders such as age, sex, race, smoking, disease duration, and comorbidity.The study, published online April 30 in Arthritis Care & Research, also showed that older, more obese individuals had greater increases in disability over time, particularly those with severe obesity. This was also seen in individuals with lower baseline Health Assessment Questionnaire scores, greater comorbidities, greater disease duration, and active smokers.
At the same time however, researchers saw a significantly larger increase in Health Assessment Questionnaire scores per year in individuals who had lost 5% or more of their weight since the age of 30. This association was evident after adjusting for body mass index at enrollment but was significantly more pronounced in individuals who were underweight. There was also a dose-dependent relationship between weight loss and subsequent worsening of disability.
Joshua F. Baker, MD, of the Philadelphia VA Medical Center and the University of Pennsylvania, and his coauthors wrote that while cross-sectional studies have shown greater disability among obese patients with RA, the longitudinal effects of obesity hadn’t been well characterized.
“Greater risks of worsening of disability in severely obese patients with RA are hypothesized to reflect the direct impact of adiposity and related comorbidities as opposed to more aggressive disease and higher disease activity,” the authors wrote. “Furthermore, in this study, adjustment for CRP [C-reactive protein] and swollen joint counts over time did not attenuate associations between severe obesity and worsening disability in the VARA [Veterans Affairs RA] registry, suggesting associations are not easily explained by more severe inflammatory disease among obese individuals.”
Commenting on the association between weight loss and worsening of disability, the authors said this may be a function of patients with more severe chronic illness experiencing weight loss.
“In RA, active inflammatory joint disease, chronic illness, comorbid disease, and worsening overall health can all contribute to weight loss,” the authors said, pointing out that while the reasons for the weight loss in the study were unknown, weight loss seen in similar observational studies was more commonly unintentional than intentional.