Pulmonary function tests, high-resolution computerized tomography, α₁-antitrypsin measurement, and early detection of pulmonary involvement in patients with systemic sclerosis

Abstract.

Objective. Pulmonary disease represents a major complication of systemic sclerosis (SSc). However, pulmonary involvement is commonly silent. In this study, we investigated the relationship between serum α₁-antitrypsin and other means of assessing pulmonary involvement. Methods. Twenty-two patients affected by SSc were studied (mean age 37.6±14.3 years, mean duration of disease 9.9±11.9 years). Fourteen had the diffuse form of disease (dSSc) and eight had the limited form (lSSc). All patients underwent pulmonary function tests, high-resolution computed tomography (HRCT) of the lungs, echocardiography, and serum assessment of α₁-antitrypsin. Results. Mean percentage of predicted values of forced vital capacity was lower in patients with dSSc than with lSSc (72.3±17.8 vs 74.5±8, P=NS). Mean percentage of predicted values of forced expiratory volume in 1-s forced vital capacity (FEV1/FVC) was lower in patients with lSSc (79.8±7.5 for lSSc vs 84.4±7.8 for dSSc, P=NS). The overall HRCT score was 5.6±5.9 with no significant difference between disease subgroups. Pulmonary hypertension was detected in two cases, both with dSSc. Alpha₁-antitrypsin was significantly higher in patients than in controls (P<0.01), with no significant difference between disease subgroups, and correlated significantly with ground glass opacities in HRCT (P<0.05) and the detection of diffusion defects (r=–0.61, P<0.01). No significant correlation was observed between skin score or degree of dyspnea with HRCT score, lung volume, or carbon monoxide diffusing capacity. Conclusion. Restrictive lung disease was more pronounced in patients with dSSc. Alpha₁-antitrypsin levels correlated significantly with ground glass opacities, an early finding of pulmonary involvement in SSc. Extent and severity of skin involvement and degree of dyspnea were not related to pulmonary involvement.