In a study of adults with rheumatoid arthritis, those who were severely obese experienced more rapidly progressing disability than patients who were overweight. This was not explained by features of their arthritis, including the amount of inflammation in their joints. In the Arthritis Care & Research study, weight loss after enrollment was also associated with worsening disability, possibly as a sign of frailty.

To examine the effects of obesity in patients with rheumatoid arthritis over time, Joshua Baker, MD, MSCE, of the Perelman School of Medicine at the University of Pennsylvania, and his colleagues examined information on 23,323 patients with rheumatoid arthritis from the National Data Bank of the Rheumatic Diseases and 1697 from the Veterans Affairs RA registry.

Severe obesity was associated with more rapid progression of disability. The study also found that patients who lost weight tended to become disabled more quickly, especially in those who were already thin. "We believe that this is because when people get older and acquire illnesses, they tend to lose weight. Therefore, the important weight loss in this study is unintentional," said Dr. Baker. "So, this study suggests that patients with rheumatoid arthritis and obesity would benefit from intentional weight loss through a comprehensive management strategy; however, when we see that someone is losing weight without trying, it's probably a poor prognostic sign, especially if they are already thin."

The findings are especially relevant when considering the rising rates of obesity in recent years. "While patients and rheumatologists may be focused mostly on disease activity, we should also consider this common condition, which can contribute to problems that are usually attributed to the arthritis itself," said Dr. Baker. "In addition, unintentional weight loss should alert us that the patient may be becoming frail and is at risk for developing new disability."

As new therapies and approaches to weight loss become available, these results will help promote their use in patients with arthritis, to help prevent disability over the long-term. The findings may also encourage health providers to recognize unintentional weight loss as a poor prognostic sign and refer patients for strength training, physical therapy, and other interventions to prevent disability.