Being overweight is linked to a higher risk of rheumatoid arthritis in women, according to data from the Nurses Health Study and Nurses Health Study II.
An estimated 1.3 million Americans have RA, and the disease typically affects women twice as often as men, according to background information for the study, which was presented in November at the American College of Rheumatologys annual meeting in Washington, D.C.
Although several case-control studies have suggested a link between excess weight and RA risk, evidence was conflicting. Seeking clarity on the subject, researchers at Brigham and Womens Hospital, Harvard Medical School and the Harvard School of Public Health investigated further to confirm and better understand the connection.
The researchers looked at the relationship between pre-existing overweight and obesity conditions and future risk of developing RA in women. The Nurses Health Study included 121,700 women ages 30 to 55. The Nurses Health Study II included 116,608 women ages 25 to 42.
All participants answered questionnaires to determine lifestyle and environmental exposures and body mass index. RA was determined based on connective tissue screening questionnaires and review of medical records. The analysis was adjusted for factors such as age, tobacco and alcohol use, breast-feeding, oral contraceptive use, menopausal status and post-menopausal hormone use.
Results showed that women who were overweight or obese had a higher incidence of developing future RA compared to women with normal weight. Women in the Nurses Health Study who were overweight had a 19% higher risk of developing rheumatoid arthritis, while women in the Nurses Health Study II had a 78% increased risk.
Among obese women in the two groups, the risk increased by 18% and 73%, respectively, compared with normal-weight women, meaning the risks increased slightly less in women classified as obese than in women classified as overweight.
“This study examining the potential role of obesity and overweight in [the]development of RA may furnish novel information about the etiology of RA, and have large potential public health implications,” Bing Lu, MD, DrPH, the studys lead investigator and a researcher at Brigham and Womens Hospital, said in a news release.