Objectives: To evaluate the clinical characteristics of patients with interstitial lung disease (ILD) in the setting of a large cohort of systemic sclerosis (SSc) patients, and to analyse the differences according to the SSc subtype (following the modification of classification criteria of the American College of Rheumatology for SSc proposed by LeRoy and Medsger), factors are associated with moderate-to-severe impairment of lung function, as well as mortality and causes of death.
Methods: A descriptive study was performed, using the available data from the Spanish Scleroderma Study Group.
Results: Twenty-one referral centers participated in the registry. By April 2014, 1374 patients with SSc had been enrolled, and 595 of whom (43%) had ILD: 316 (53%) with limited cutaneous SSc (lcSSc), 240 (40%) with diffuse cutaneous SSc (dcSSc), and 39 (7%) with SSc sine scleroderma (ssSSc). ILD in the lcSSc and the ssSSc subsets tended to develop later, and showed a less impaired forced vital capacity (FVC) and a ground glass pattern on high-resolution computed tomography (HRCT) less frequently, compared with the dcSSc subset. Factors related to an FVC < 70% of predicted in the multivariate analysis were: dcSSc, positivity to anti-topoisomerase I antibodies, a ground glass pattern on HCRT, an active nailfold capillaroscopy pattern, lower DLco, older age at symptoms onset, and longer time between symptoms onset and ILD diagnosis. Finally, SSc-associated mortality and ILD-related mortality were highest in dcSSc patients, whereas that related to pulmonary arterial hypertension was highest in those with lcSSc-associated ILD.
Conclusions: Our study indicates that ILD constitutes a remarkable complication of SSc with significant morbidity and mortality, which should be borne in mind in all three subgroups (lcSSc, dcSSc, and ssSSc).
Keywords: Interstitial lung disease; Mortality; Pulmonary hypertension; Systemic sclerosis.