Lung involvement in patients with primary Sjögren's syndrome: what are the predictors?

The aim of this study was to investigate the prevalence, predictors and radiological findings of primary Sjögren's syndrome (pSS)-associated lung involvement. This retrospective cohort study included 123 patients with demographic, clinical, laboratory and radiological data who were diagnosed with pSS. Lung involvement was defined based on the presence of pulmonary signs/symptoms and/or impaired pulmonary function tests along with alterations in high-resolution computerized tomography (HRCT). Thirty patients (24.4%) had pulmonary signs/symptoms at the initial presentation and/or during the follow-up period. Based on the criteria, 14 patients (11.4%) were defined as having pSS with lung involvement. The smoking rate, male/female ratio and the mean ages were found to be higher in patients with lung involvement (P < 0.05). Positive IgM-rheumatoid factor (RF), anti-La and anti-Ro results, the presence of hypergammaglobulinemia and lymphopenia had high specificity despite the low sensitivity rates to detect pSS-associated lung disease. A significant difference was found in forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV(1)) results between the patients with and without lung involvement. Impaired FEV(1) had high specificity and positive predictive value compared to impaired FVC, particularly in non-smoker patients. The most frequent HRCT finding was ground-glass attenuation (64.3%). Other common findings were bronchiectasis, reticular pattern and honeycombing. The lesions involved predominantly the lower lobes. In conclusion, the presence of hypergammaglobulinemia and lymphopenia, positivity for RF, anti-La and anti-Ro, and impaired (FVC) and/or FEV(1) values could be the predictive parameters with a high specificity despite the low sensitivity rates. Smoking history, male gender and age are also risk factors. These parameters may be helpful to distinguish pSS-associated lung involvement from lung disorders unrelated to pSS.