by Will Boggs, MD

Last Updated: 2008-06-02 14:02:18 -0400 (Reuters Health)

NEW YORK (Reuters Health) – Rheumatoid arthritis (RA) patients with a high body mass index (BMI) have less joint destruction in the early stage of the disease than do their lower-BMI counterparts, according to a report from the Netherlands in the June issue of the Annals of the Rheumatic Diseases.

"This is an intriguing observation that needs to be thoroughly investigated," Dr. Annette H. M. van der Helm-van Mil told Reuters Health. "It may reveal new biological mechanisms that have a protective influence on joint damage in RA."

Dr. van der Helm-van Mil and colleagues from Leiden University Medical Center investigated whether obesity is a risk factor for the development of RA among 570 patients with undifferentiated arthritis, and whether the BMI of patients at onset of RA is correlated with the level of radiological joint destruction during 3 years of follow-up.

BMI and obesity had no influence on the risk of progressing from unclassified arthritis to RA, the authors report.

In contrast, there was an inverse correlation between baseline BMI and radiological joint destruction, as measured by the Sharp-van der Heijde score, after 3 years of follow-up. BMI correlated inversely with both the total erosion score and the total joint space narrowing score.

In further analyses, these correlations were apparent only in patients positive for anti-cyclic citrullinated peptide (anti-CCP) antibodies, the investigators found, and were completely absent in anti-CCP-negative patients with RA.

These findings were replicated in a second, independent cohort of 247 patients, the researchers note.

"Our department of rheumatology will perform further studies on the effect of obesity on RA as well as osteoarthritis," Dr. van der Helm-van Mil said. "This will concern, amongst others, studies on synovial tissue from patients with and without overweight and mouse models and serological studies on adipocytokines."

She hopes such studies "subsequently can lead to the development of new targeted therapies."

Ann Rheum Dis 2008;67:769-774.

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