A longitudinal study of pulmonary function in Danish patients with systemic sclerosis

Objective: To determine the types, prevalence and development of respiratory abnormalities in patients with systemic sclerosis (SSc), and to correlate the results with clinical and serological findings. Methods: 176 patients with SSc observed longitudinally were retrospectively included in the study. The change per year of vital capacity (VC), forced expiratory volume in one second/vital capacity (FEV1/VC), diffusing capacity (DLco) and diffusing constant (Kco) of carbon monoxide from the first till the latest pulmonary function test were correlated to clinical and serological findings, including anti-centromere, anti-Scl-70, and antinucleolar antibodies. Results: An isolated reduction of DLco was seen in 47% and a restrictive ventilatory pattern in 25% of the patients. Restrictive ventilatory pattern correlated to pulmonary fibrosis, dyspnoea, a low prevalence (13%) of anticentromere antibodies and a high prevalence of anti-Scl-70 antibodies (36%). Progression of DLco reduction was related to long disease duration, presence of anticentromere antibodies and absence of treatment with penicillamine. Conclusion: Pulmonary involvement is common in patients with SSc. The occurrence of different serological abnormalities in patients with restrictive disease and in patients with progressive isolated reduction of DLco, suggests that the two types of pulmonary damage may have different pathogeneses rather than being different stages in the progression of pulmonary damage.