“Some previous research studies suggest that antibodies related to rheumatoid arthritis (RA) may be produced at sites of inflammation in the lungs and airways,” says the senior author of the new study, Jeffrey Sparks, MD, an assistant professor of medicine at Brigham and Women’s Hospital and Harvard Medical School in Boston. “However, it was previously uncertain whether patients with airway diseases, such as asthma and chronic obstructive pulmonary disease, are more likely to develop RA,” Dr. Sparks said. RELATED: Rheumatoid Arthritis Increases Risk for COPD in Women
How Airway Disease Affects RA Risk
For their research, Sparks and colleagues examined data from 205,153 female nurses who were followed for approximately two decades. None of them had rheumatoid arthritis when they joined the study, but 15,148 had asthma and 3,573 had COPD. By the end of follow-up period, 1,060 women had been diagnosed with rheumatoid arthritis. Women with asthma were 53 percent more likely to be diagnosed with RA during the study than the women in the study without an airway disease, and women with COPD were 89 percent more likely to get an RA diagnosis. The researchers also looked at smoking history, because smoking is a known risk factor for both breathing disorders (including asthma and COPD) and rheumatoid arthritis. Smoking-related respiratory illnesses like emphysema and bronchitis are considered types of COPD. Asthma was only associated with an increased risk of rheumatoid arthritis among women who never smoked. There didn’t appear to be a statistically significant increased risk of RA among women with asthma or COPD who were current or former smokers (but that may be because smoking already increases their RA risk so much). With COPD, however, the connection with rheumatoid arthritis was strongest among current and former smokers older than 55. These women had more than twice the risk of RA of women who didn’t have asthma or COPD, the study found. Even though this study only included women (because the data set the researchers used included only women), it’s likely this elevated risk of RA among people with asthma and COPD also exists for men and people of other ages, says Joshua Baker, MD, an assistant professor of rheumatology and epidemiology at the University of Pennsylvania and a physician at the Philadelphia VA Medical Center. More studies are needed, according to Dr. Baker, who was not involved in this study. “As far as we know, the processes that are important in the lung are similar between men and women and between younger and older people, though it is difficult to know for sure.” RELATED: What Causes Asthma and Asthma Flare-Ups?
Chronic Inflammation, a Known RA Risk Factor, May Explain the Connection
Rheumatoid arthritis develops when white blood cells that normally protect the body from infections enter tissue in the joints, causing inflammation, swelling, stiffness, and pain. While scientists aren’t entirely sure why this happens, genetics are thought to play a role, along with environmental factors like exposure to tobacco smoke or air pollution or other lung irritants. (A study published in December 2015 in the Annals of the Rheumatic Diseases, for example, found that workers exposed to textile dust in factories were almost three times more likely to develop RA than people without this exposure.) Though RA has been linked to increased risk of lung problems, the new Arthritis & Rheumatology study is one of the first to document that respiratory conditions like asthma and COPD may be linked to causing RA. Chronic inflammation is thought to play a role in the development of asthma, COPD, and rheumatoid arthritis, and might help explain the connection, says Axel Finckh, MD, a rheumatologist at the University of Geneva in Switzerland. What the current study offers is fresh evidence that airway inflammation present in people with asthma and COPD might kick off processes in the body that lead to RA, much like tobacco smoke and other pollutants do. “There is more and more evidence that RA does not start one day in the joints,” says Dr. Finckh, who wasn’t involved in the study. Since smokers often have lung problems, it has been difficult to tease out whether smoking itself may cause RA or if smoking-related lung diseases like COPD may be the culprit, Baker adds. “This study, to my knowledge, is the first to really try to look at the association between lung disease and RA independent of the effects of smoking,” says Baker, who wasn’t involved in the study. The study doesn’t definitively answer this question because it wasn’t a controlled experiment designed to prove whether or how asthma or COPD might directly cause RA, or what role smoking might play in this process. One limitation of the study is that it included mostly white, affluent, and educated women. It’s possible that people with more severe lung disease in the study were also heavier smokers, or that other factors might explain the connection between breathing disorders, Baker says.
The Bottom Line for Patients With Asthma or COPD
What the results do suggest is that patients with asthma and COPD should be closely monitored for any symptoms of rheumatoid arthritis and evaluated for RA if they have joint pain, so they can be diagnosed earlier when RA is easier to treat, the study team concluded in their paper. Medications like corticosteroids (the standards of care for asthma and COPD), work by reducing chronic airway inflammation. It’s possible that the treatment might also lower the risk of RA in people with asthma and COPD (because, again, it’s that chronic inflammation that is also thought to be linked to RA). But more research is still needed to confirm if this is the case, according to the researchers. It’s also important to note that this investigation was limited in scope by the fact that the conclusions are based on survey data. Characteristics of asthma and COPD were only collected once, so there wasn’t a good way to evaluate whether disease severity, subtype, and management affected RA risk. The researchers note that more research on all those questions is warranted. In the meantime, there’s plenty people can do to minimize their risk of RA whether or not they have asthma or COPD. “The first and most obvious advice is to stop smoking,” Baker says. “Exercise is also important and can help improve respiratory health for those with and those without lung disease.” RELATED: Why Fitness Helps With Managing Chronic Disease
