Deterioration of lung function is associated with presence of IgM rheumatoid factor and smoking in patients with systemic sclerosis.

Smoking is a known risk factor for the development of several lung diseases, autoimmune diseases, and IgM rheumatoid factor (RF) in nonrheumatic persons. In patients with rheumatoid arthritis and IgM RF the diffusion capacity is decreased in smokers but not in nonsmokers. In the present study of patients with systemic sclerosis (SSc) the influence of smoking and IgM RF on the lung function was calculated.