By Mary Elizabeth Dallas
Conversely, the researchers also found that unexplained weight loss might also signal problems for these patients, because it could mean that they're at greater risk for disability.
"While patients and rheumatologists may be focused mostly on disease activity, we should also consider this common condition [obesity], which can contribute to problems that are usually attributed to the arthritis itself," said study author Dr. Joshua Baker.
"In addition, unintentional weight loss should alert us that the patient may be becoming frail and is at risk for developing new disability," he added. Baker is an assistant professor of medicine at the University of Pennsylvania's Perelman School of Medicine.
Rheumatoid arthritis is an autoimmune condition. It develops when immune cells that normally fight germs attack the lining of the joints, or cartilage. This causes the joints to swell and the surrounding bones, ligaments and muscles to gradually erode. Rheumatoid arthritis worsens over time, often leading to disability.
For the study, Baker and his colleagues looked at the effects of obesity on the progression of rheumatoid arthritis in just over 25,000 people with the disease.
The investigators found that the disease advanced more quickly among those who were very obese. This was true regardless of the level of inflammation in their joints.
In addition, people who were thin but lost weight without trying also became disabled more quickly.
The study was published April 30 in the journal Arthritis Care & Research.
"So, this study suggests that patients with rheumatoid arthritis and obesity would benefit from intentional weight loss through a comprehensive management strategy," Baker said in a journal news release."
"However, when we see that someone is losing weight without trying, it's probably a poor prognostic sign, especially if they are already thin," he added.
Although the study could not prove a cause-and-effect link, the researchers suggested that new treatments and strategies to help people maintain a healthy weight might help prevent disability among people with rheumatoid arthritis.
And, Baker's team noted, the findings could help doctors recognize signs of frailty among their rheumatoid arthritis patients who may benefit from strength training and physical therapy.