This is more common in cases of bronchiolitis obliterans, pulmonary fibrosis, or pulmonary hypertension. Most complications are not fatal, but does reduce life expectancy to an estimated 5 to 10 years. Epidemiology
The prevalence of RA is around 0.3–1.2% (0.92% of Americans). Women are 2–3 times more susceptible than men. The prevalence of rheumatoid lung disease in patients with RA depends on the method used for diagnosis: chest X rays (5%), high resolution CT scans (10–40%).A study showed 582 patients with RA and 603 subjects without RA were followed for a mean of 16.4 and 19.3 years, respectively. The lifetime risk of developing ILD was 7.7% for RA patients and 0.9% for subjects without RA. The risk of developing ILD was higher in patients with older age at RA onset, among male patients and for individuals with parameters that indicate more severe RA. Survival of RA patients diagnosed with ILD was worse compared to RA patients without ILD. ILD contributed approximately 13% to the excess mortality of patients with RA patients when compared to the general population.
Rheumatoid lung disease is a disease of the lung associated with RA, rheumatoid arthritis. Rheumatoid lung disease is characterized by pleural effusion, pulmonary fibrosis, lung nodules and pulmonary hypertension. Common symptoms associated with the disease include shortness of breath, cough, chest pain and fever. It is estimated that about one quarter of people with rheumatoid arthritis develop this disease, which are more likely to develop among elderly men with a history of smoking.Rheumatoid lung is separate from but often associated with Interstitial lung disease(ILD). Signs and symptoms
Most common:

Chest Pain
Cough
Fever
Shortness of breath
Joint pain, stiffness, swelling
Skin nodulesPeople may not present with all these symptoms or none at all. From most to least common:

Pleural involvement (pleurisy, effusions)
Pulmonary parenchymal nodules, more common in men than in women
Rheumatoid-associated interstitial lung disease
Bronchiolitis obliterans organizing pneumonia
Obliterative bronchiolitis (obstructive lung disease/bronchiectasis)
Rheumatoid-associated pulmonary hypertension
Pulmonary vasculitis/arteritis
Shrinking lung syndrome
Miscellaneous: MTX, cricoarytenoid arthritis, infection, cancer

Causes
The exact cause of rheumatoid lung disease is unknown. However, associated factors could be due largely to smoking. Sometimes, the medicines used to treat rheumatoid arthritis, especially methotrexate, may result in lung disease.Prevention:

Stop smoking: Chemicals found in cigarettes can irritate already delicate lung tissue, leading to further complications. Having regular checkups: The doctor could listen to lungs and monitor breathing, because lung problems that are detected early can be easier to treat. Mechanism
RA is a complex and poorly understood disease. However, the characteristic presence of antibodies to citrullinated proteins (anti-CCP) suggests that there are pathogenic mechanisms unique to RA. Recent studies suggest a link between smoking, HLA-DRBSE, anti-CCP and RA.