Study: Obesity Skews Rheumatoid Arthritis Biomarker

Obesity is associated with greater C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) in women with rheumatoid arthritis (RA), but this association appears to be related to fat mass rather than disease activity.

The study examined associations between body mass index (BMI) and CPR and ESR in 451 participants with RA involved in the cross-sectional Body Composition cohort and 1652 participants with RA involved in the longitudinal Veterans Affairs Rheumatoid Arthritis registry. Comparisons between participants from the 2 cohorts with the general population were made using the National Health and Nutrition Examination Survey.
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Overall, high BMI was associated with high CRP in both women with RA and women in the general population, and was highest in women with severe obesity. In addition, the association between high BMI and high CRP remained after researchers adjusted for joint counts and patient global assessment, but was attenuated when researchers adjusted for fat mass index.

Likewise, modest positive associations between BMI and ESR were observed in women.

Lower BMI in men with RA was associated with high CRP and ESR, which contrasted with the positive associations found in men in the general population.

“Obesity is associated with greater CRP and ESR in women with RA. This association is related to fat mass and not RA disease activity,” the researchers concluded. “Low BMI is associated with greater CRP in men with RA–this unexpected finding remains incompletely explained but likely is not a direct effect of adiposity.”

—Melissa Weiss

Reference:

George MD, Giles JT, Katz PP, et al. The impact of obesity and adiposity on inflammatory markers in patients with rheumatoid arthritis [published online April 10, 2017]. Arthritis Care Res. doi:10.1002/acr.23229.