Prevalence of interstitial lung involvement in patients with connective tissue diseases assessed with high-resolution computed tomography

Objectives: To assess the prevalence of interstitial lung disease (ILD) in patients with different forms of connective tissue disease (CTD) using non-invasive procedures including high-resolution computed tomography (HRCT) and to evaluate the relationship between the imaging and functional status of the patients. Methods: Eighty-one subjects with CTD (47 inpatients and 34 outpatients) were evaluated with pulmonary function tests (PFT) and radiological investigations. The extent and severity of lung disease was quantified with an HRCT scoring system previously used in patients with systemic sclerosis (SSc). Interstitial lung involvement was defined as predominantly fibrotic or inflammatory based on HRCT abnormalities. Results: HRCT abnormalities suggestive of ILD were observed in 69 patients (85.1%), whereas PFT and plain radiograph alterations occurred less frequently (40.7%). The most frequent HRCT abnormalities were septal/ subpIeural lines and ground-glass appearance whereas lesions consistent with advanced fibrosis were observed in a minority of patients. The HRCT score was higher in patients with abnormal PFT (p < 0.001). Thirty-five patients had predominant fibrosis and 34 patients predominantly inflammatory abnormalities. A score of 10 points represented the best compromise between sensitivity and specificity in predicting functional impairment. Conclusions: A high prevalence of ILD was found based on HRCT abnormalities. However, HRCT scans characterized by minor abnormalities have poor specificity for clinically significant disease and functional findings should also be considered. The large number of patients with predominantly inflammatory HRCT abnormalities suggests that many cases of ILD may be diagnosed in a relatively early stage of the disease.