A high body mass index has a protective effect on the amount of joint destruction in small joints in early rheumatoid arthritis.

BACKGROUND: Obesity is a state of chronic low-grade inflammation that predisposes people to several diseases and that is increasingly prevalent. Rheumatoid arthritis (RA) is marked by the presence of proinflammatory cytokines and, in general, the presence of high levels of inflammatory markers is associated with a severe disease course and joint damage.
OBJECTIVES: To evaluate prospectively (a) whether obesity is a risk factor for the development of RA and (b) whether the body mass index (BMI) is associated with the amount of joint destruction in early RA after 3 years' follow-up.
METHODS: In a cohort of 570 patients with undifferentiated arthritis, the relation between the BMI and the development of RA during 1 year of follow-up was assessed. In a cohort of 488 patients with early RA the correlation between the BMI and degree of radiological joint destruction (Sharp-van der Heijde score) after 3 years of follow-up was determined. The findings were replicated in an independent cohort of 247 patients with early RA.
RESULTS: Obesity did not influence the likelihood of developing RA. In both RA cohorts, the BMI was inversely correlated with the Sharp-van der Heijde score after 3 years' follow-up (r = -0.15, p = 0.025 for the Leiden EAC and r = -0.27, p<0.001 for the replication cohort). Linear regression analyses in both cohorts showed that the BMI was independently and inversely associated with the level of joint destruction in anti-CCP-positive patients with RA, but not in anti-CCP-negative patients.
CONCLUSIONS: A high BMI is associated with a less severe disease outcome in anti-CCP-positive patients with RA.