The characteristics of chest HRCT and pulmonary function tests in lung‐onset primary sjogren's syndrome

INTRODUCTION: Interstitial lung disease (ILD) can manifest before the diagnosis of primary Sjögren's syndrome (pSS), however, the underlying mechanisms remain unclear. The aim of this study is to investigate the characteristics of lung‐onset pSS using chest high‐resolution computerized tomography (HRCT) and pulmonary function tests (PFTs). METHODS: The data of 102 patients with pSS‐ILD were retrospectively analyzed. The patients were divided into two groups: lung‐onset group and the nonlung‐onset group. The chest HRCT, PFTs, and clinical and laboratory data were evaluated and compared. RESULTS: Among the 102 patients with pSS‐ILD, 59 (57.8%) were lung‐onset and 43 (42.2%) were nonlung‐onset. Chest HRCT in the lung‐onset group showed higher percentage of usual interstitial pneumonia and nonspecific interstitial pneumonia, the difference did not reach statistical significance. The total HRCT score was higher in the lung‐onset group, compared with the nonlung‐onset group (2 [2, 3], vs. 2 [1, 2], p = .014). Total lung capacity (TLC) (%pred) [(75.4 ± 16.2) versus (82.8 ± 19.4), p = .049] and forced vital capacity (FVC) (%pred) [(82.2 ± 19.9) versus (91.6 ± 28.3), p = .050] were significantly lower in the lung‐onset group, compared with the nonlung‐onset group. Residual volume (RV)/TLC (%) significantly increased more than 40% in the lung‐onset group (p = .015). Restricted ventilation disorder, small airway obstruction and reduced diffusing capacity of the lung for carbon monoxide/alveolar volume (%Pred) were more common in the lung‐onset group (p = .038, p = .050, and p = .050, respectively). Correlation analysis showed that HRCT score was positively correlated with the interval between the onset of pulmonary symptoms and the diagnosis of ILD, serum CA125, and serum CEA. TCL (%pred), VC (%pred), FVC (%pred) were negatively correlated with serum CA125. CONCLUSION: Lung‐onset is common in pSS patients with more severe lung function impairments. Serum biomarkers, such CA125, CEA, and ALB, were associated with the severity of lung damage.