Lung Diseases and RA

A variety of lung diseases, including pleuritis, pulmonary fibrosis, pulmonary rheumatoid nodules, and interstitial lung disease (ie. bronchiolitis and pneumonia), can affect patients with RA. Abnormal airway function is common in patients with RA. Pulmonary function testing may be below normal in up to 38% of patients with RA. In one study, 16% of non-smoking RA patients were found to have some airway obstruction, a rate much higher than that seen in individuals in the general population without RA.^1,2

Pleuritis

Pleuritis, which can be caused by autoimmune disorders including systemic lupus erythematosus and RA, is an inflammation of the lining of the cavity, or pleura, surrounding the lungs. Every time the lungs expand during inhalation, they rub against the inflamed pleura, causing sharp pain.¹

Pulmonary fibrosis

Pulmonary fibrosis is the formation of fibrous tissue inside the lungs that appears on x-ray as scarring. The formation of scar tissue interferes with the ability of the lung to expand normally upon inhalation and can lead to chest discomfort, shortness of breath, fatigue, weakness, and a chronic cough.^1,2

Interstitial lung disease

One study estimated that about 6% of patients with RA develop some form of interstitial lung disease, a range of conditions that affect the space and tissues surrounding the air sacs (alveoli) in the lungs. Interstitial lung disease associated with RA typically includes interstitial pneumonias and bronchiolitis, as well as damage to alveoli. RA-related interstitial lung disease appears to be more common in men than women, affecting 26% of men compared to 4% of women. However, this may be related to the greater frequency of smoking, a factor that increases risk for RA-related lung disease, among men than women. Men with RA are twice as likely to smoke as women.^1,2

Rheumatoid nodules

The formation of rheumatoid nodules in the lungs occurs in a small minority of patients with RA (less than 1%) and is more common in men than women. Typically, RA nodules, which are firm lumps of tissue, are asymptomatic. They may form before or after RA has been diagnosed, but are more common in severe RA. Additionally, they may increase in size or remain the same size or disappear spontaneously.²

Lung disease induced by RA medication

Some medications used to treat RA can result in damage to the lungs. For instance, the disease-modifying anti-rheumatic drug (DMARD) methotrexate can result in pulmonary side effects in 1% to 5% of patients. Interstitial lung disease has also been linked to several biologics, including the TNF-inhibitor treatments infliximab (Remicade), etanercept (Enbrel), golimumab (Simponi), certolizumab pegol (Cimzia), and adalimumab (Humira).²

Factors that increase risk for developing lung disease

A number of factors have been linked to increased risk for developing RA-related interstitial lung disease. These include genetic factors (the presence of certain variations of common genes) that increase susceptibility to lung disease and environmental factors. Smoking, which is a clear risk factor for development of RA, also increases the chances of developing lung disease in patients with RA.²

Treatment of RA-related lung disease

Glucocorticoid (also called corticosteroid or steroid) treatment (sometimes used in conjunction with cytotoxic drugs) is typically used to manage interstitial lung disease associated with RA. While experience with other agents is limited, in cases where interstitial lung disease is resistant to glucocorticoids, treatment with cyclophosphamide, cyclosporine, or azathioprine may be useful.²

Management approaches for pleuritis include glucocorticoid treatment (oral) and drainage of the fluid accumulation caused by inflammation.²