Background Interstitial lung disease (ILD) is a common complication of various connective tissue diseases, like scleroderma, polymyositis or mixed connective tissue disease (MCTD). The development of ILD is in many cases asymptomatic, although autopsy found lesions typical for the ILD in 90–100% . In the case of MCTD ILD is the most common pulmonary involvement with incidence of 47,1% (active form- 66% of them) and its severe type - progressive fibrosis characterize 20.8% after 4.2 years mortality rate .
Objectives The aim of the study was to estimate the prevalence of ILD and pulmonary fibrosis in a cohort of MCTD patients, and to identify clinical and immunological predictors of this complication.
Methods The study included 79 patients (the median age =44 years, 83.5% of women), who fulfilled Alarcon-Segovia and Kasukawa sets of criteria for MCTD.
Clinical features of MCTD, autoantibody profile and serum cytokine (IL-1, IL-10, IL-21, IL-23, TNFα, IFNγ, VEGF) concentrations were assessed. Screening chest X-ray, and if needed pulmonary function tests and high resolution computed tomography (HRCT) were performed additionally.
ILD was defined as active, reversible interstitial lung disease with symptoms such as dyspnoea and dry cough, proven radiologically by presence of interstitial lesions in X-ray or ground-glass opacity in HRCT ± decrease in pulmonary function tests by 10% in forced vital capacity (FVC) or diffusing capacity of the lungs for carbon monoxide (DLCO).
Results ILD and pulmonary fibrosis were present in 19% of MCTD patients and this group was characterized by older age, longer disease duration, more frequent systemic damage, and higher disease activity comparing to the rest of study group. The most common findings among patients with ILD were abnormal FEV1 (80% vs 15,4%) and oesophageal involvement (4,4 vs 19,7%). Concomitance of pulmonary arterial hypertension (PAH) and ILD in MCTD were observed in only 2,5% of examined patients. Moreover, patients with ILD were less often positive for anti-SmB antibody than the ILD-free subjects (11.1 vs 37.7%), but similar cytokine concentrations was stated in both groups.
Conclusions In MCTD pulmonary involvement (ILD and/or pulmonary fibrosis) develops mostly in patients with long lasting, clinically severe disease, accompanied by low frequency of anti-SmB antibody presence.
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Disclosure of Interest None declared