Obesity potentially linked to higher CRP, ESR levels in women with RA
Obesity appears to be associated with increased levels of C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) in women with rheumatoid arthritis (RA), according to a recent study.
“CRP and ESR are routinely used in the diagnosis and assessment of disease activity in patients with RA ... higher levels of CRP have been shown to be associated with greater body mass index (BMI) and adiposity, especially among women,” according to the researchers.
Data from the BC* and VARA** cohorts (women with RA, n=451 and 1,652, respectively) were compared with the NHANES*** and NHANES I cohorts (general population adults, n=10,813 and n=12,227, respectively). [Arthritis Care and Researcher 2017;doi.org/10.1002/acr.23229]
After adjusting for age, race, and smoking status, CRP was associated with BMI across the evaluated cohorts (β=0.057, 95 percent confidence interval [CI], 0.035–0.080; p<0.001 in BC, β=0.030, 95 percent CI, 0.014–0.045; p<0.001 in VARA, and β=0.097, 95 percent CI, 0.092–0.101; p<0.001 in NHANES), with significantly higher levels in severely obese women (≥35 kg/m2, p<0.001).
ESR was also associated with BMI across the evaluated cohorts (β=0.020, 95 percent CI, 0.016–0.024; p<0.001 in NHANES I), but with significantly higher levels in severely obese women in the two RA cohorts (β=0.033, 95 percent CI, 0.010–0.057; p<0.006 in BC and β=0.016, 95 percent CI, -0.001 to 0.032; p<0.051 in VARA).
CRP and ESR were also associated with fat mass (FMI Z-score, β=0.52, 95 percent CI, 0.35–0.69; p<0.001 and β=-0.20, 95 percent CI, 0.01–0.40; p<0.05, respectively) but not lean mass (ALMI Z-score, β=-0.18, 95 percent CI, -0.36 to -0.01; p<0.05 and β=-0.01, 95 percent CI, -0.24 to 0.23, respectively).
The findings were consistent with a previous study that demonstrated an association between adiposity and CRP levels in women with RA. [Arthritis Rheum 2008;58:2632-2641]
“BMI is an imperfect measure of adiposity, especially in RA … and as shown in this
study, is also highly associated with inflammatory markers in women with RA,” said the researchers.
Despite the large sample sizes, the researchers acknowledged that data from the two RA cohorts was insufficient to estimate results. “Disease activity and ESR were also not measured in all studies or at all study observations, reducing power in these analyses,” they said.
*BC: Body Composition cohort
**VARA: Veterans Affairs Rheumatoid Arthritis registry
***NHANES: National Health and Nutrition Examination Survey