Background: Interstitial lung disease (ILD) is a frequent complication in systemic sclerosis (SSc). So, an increased awareness of this complication is a real need in the clinical setting, because it may affect the prognosis of patients. In particular, an accurate strategy is desirable in order to detect ILD in its stages. So, we investigate the validity of ultrasound (US) in detecting subclinical ILD in SSc, and to determine its potential in disease progression.
Methods: 133 patients without respiratory symptoms and 133 healthy controls were included. Borg scale, Rodnan skin score (RSS), pulmonary auscultation, chest radiographs and respiratory function tests (RFT) were performed. An expert rheumatologist performed the lung US. High-resolution CT (HRCT) was also performed. After the baseline assessment, the patients were followed every 3 months for 12 months.
Results: A total of 79 of 133 patients (59.4%) showed US signs of ILD in contrast to healthy controls (4.8%) (p=0.0001). The clinical and laboratory variables associated with ILD were anti-centromere antibodies (p=0.005) and RSS (p=0.004). A positive correlation was demonstrated between the US and HRCT findings (p=0.001). Sensitivity and specificity of US in detecting ILD was 91.2% and 88.6% respectively. A good inter-observer reliability was observed (k = 0.72).
In the follow-up, a total of 30 patients out of 79 (37.9%) who demonstrated US signs of ILD at baseline, showed changes in the ILD score by US.
Conclusions: US showed a high prevalence of subclinical ILD in SSc patients. It demonstrated to be a valid, reliable and feasible tool to detect ILD in SSc and to monitoring the disease progression.