Association of silica exposure with chest HRCT and clinical characteristics in systemic sclerosis

Thoracic lymphadenopathy (LA) has been identified as a key prognostic factor in interstitial lung disease (ILD) of all-cause. Crystalline silica is a risk factor of systemic sclerosis (SSc). The association of a history of crystalline silica exposure with chest high-resolution computed tomography (HRCT) features and thoracic LA are still to be determined in SSc patients.

We performed an observational study to assess the association of lifetime exposure to silica, with chest HRCT characteristics in a population of SSc patients fulfilling the 2013 ACR/EULAR classification criteria for SSc.

A specific questionnaire based on a multidisciplinary approach was used to assess occupational and non-occupational exposure to silica in 100 consecutive SSc patients. Clinical characteristics and chest HRCT at diagnosis and at the latest visit were evaluated to assess the association of silica exposure with disease characteristics.

16% of the overall population and 58% of men had an occupation with specific high silica exposure. A higher silica exposure score was associated with the combination of mediastinal and hilar LA on HRCT (OR=8.09, 95%CI=2.01-32.52, P = 0.002). More than 12% of the patients had a combination of mediastinal and hilar LA on HRCT. This marker of silica exposure was predictive of worsening of pulmonary involvement in univariate analysis (OR=5.86, 95%CI=1.64-20.89, P = 0.007) and multivariate analysis (OR=4.57, 95%CI =1.12-18.60, P = 0.034).

In patients with SSc, the combination of mediastinal and hilar LA on HRCT was associated with exposure to silica and was also significantly associated with a more severe evolution of ILD.