The contribution of computed tomography (CT) to the assessment of rheumatoid lung disease is universally recognized. Our objective was to define the usefulness of high-resolution CT (HRCT) in evaluating lung abnormalities in unselected patients with rheumatoid arthritis (RA) and to determine whether HRCT findings were correlated with clinical and lung function test (LFT) abnormalities.
We prospectively investigated HRCT findings in 75 consecutive RA patients and looked for correlations with clinical, radiological, blood gas, and LFT variables. The 63 women and 12 men had a mean age of 48+/-14 years and a mean disease duration of 8+/-88 months (2 months-27 years). Most of the patients (77.3%) had no known history of respiratory disease.
Respiratory symptoms were noted in one third of patients. HRCT findings were abnormal in 49.3% of patients, showing interstitial disease in 28% and bronchiectasis in 18.7%. Advanced fibrosis was not noted. One patient had bronchiolitis obliterans with organizing pneumonia and another had constrictive bronchiolitis. Smaller proportions of patients had emphysema (13.3%), alveolar involvement (12%), pleural involvement (9.3%), or rheumatoid nodules (4%). HRCT findings were abnormal in 48.6% of the patients with no respiratory symptoms. Factors significantly associated with HRCT abnormalities were age older than 40 years, positive tests for IgM rheumatoid factors, hypoxia at rest, and LFT evidence of distal airway disease. Neither Sjogren's syndrome nor RA duration was significantly associated with the risk of HRCT abnormalities.
In our population of unselected RA patients, HRCT proved sensitive in detecting abnormalities that were clinically silent and missed by plain radiography. Correlations between HRCT abnormalities and results of other investigations were inconsistent. Thus, these various investigations may complement one another.