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Think infection when lung issues strike in RA.

KEYSTONE, COLO. -- The top diagnostic priorities when a lung problem is detected in a patient with underlying rheumatoid arthritis or another autoimmune disease are to rule out infection and drug reactions.

"The first 50 things on my list are infection and drug-induced disease. Almost all the drugs used to treat the autoimmune diseases put you at increased risk for infection--usually atypical infection. And all of the drugs used in treating autoimmune diseases have clearly been associated with the development of drug-induced lung disease, although some more than others," Dr. Kevin K. Brown observed at a meeting on allergy and respiratory diseases.

Excluding infection up front is a high priority because it's the one type of interstitial lung disease (ILD) that's readily treatable. Also, a missed pulmonary infection spells trouble because efforts to treat nearly all other forms of ILD entail immunosuppression, which will make an infection worse, noted Dr. Brown, vice chairman of the department of medicine at National Jewish Health.

Lung problems are extremely common in patients with autoimmune diseases. Chest abnormalities are present on high-resolution CT in 70%-90% of patients with systemic lupus erythematosus, rheumatoid arthritis, scleroderma, or other collagen vascular diseases, although the abnormalities often don't show up on a chest x-ray. Although many of these patients report having no respiratory complaints, a careful history not uncommonly indicates that these patients have made lifestyle changes because of exertional shortness of breath or other symptoms.

"It used to be that patients with rheumatoid arthritis were not very active because if they were active they paid for it that night when their synovitis acted up. Now it's a rare patient whose synovitis can't be effectively managed. So we're seeing patients get off the couch, being very active, but having trouble getting up and down the stairs, not because of their arthritis but because of their lung disease," he said at the meeting, which was sponsored by the National Jewish Medical and Research Center.

One of the biggest offenders in terms of drug-induced ILD in patients with autoimmune disease is methotrexate. Probably 5%-7% of patients on methotrexate have drug-induced ILD. There are so many options available today for the treatment of collagen vascular diseases that, when Dr. Brown identifies ILD in a patient being treated for an autoimmune disease, he simply asks that the drug--whatever it is--be stopped and the patient be put on something else rather than trying to prove cause and effect.

An ILD in the setting of autoimmune disease is associated with lower quality of life, more impaired functional status, greater health care costs, and markedly reduced survival over the next 4-5 years compared with the same autoimmune disease without ILD.

Dr. Brown and others have shown that the specific autoimmune disease doesn't really matter: The prognosis for patients with an ILD and an autoimmune disease is significantly worse than for those with that autoimmune disease alone.

Clinical symptoms suggestive of autoimmune disease in a patient with an ILD include weight loss, fever, onset of Raynaud's after about age 40 years, gastroesophageal reflux, rash, keratoconjunctivitis sicca, arthralgias, and myalgias. A laboratory red flag that the ILD may be the first manifestation of an underlying autoimmune disease is the presence of nucleolar-staining antinuclear antibodies. Specific patterns of abnormal findings on CT and pathology also suggest rheumatologic disease, noted Dr. Brown, who reported having no conflicts of interest.
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Author:Jancin, Bruce
Publication:Family Practice News
Date:May 1, 2010
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