Sjögren's syndrome (SS) affects the respiratory system, but previous studies have not assessed the role of subclinical SS in lung disease. The aim of this investigation was to explore the potential role of subclinical SS as a factor in the pathogenesis of various diffuse lung diseases.
This single-cohort prospective study was performed over a 5-year period in 313 consecutive patients with diffuse lung disease, who had neither primary xerosis nor a diagnosis of SS. They were referred for the Saxon test and underwent additional tests for SS when decreased saliva production was detected.
The subjects included 109 patients with sarcoidosis, 77 with various interstitial pneumonias, 49 with bronchiectasis, and 78 with other diseases. The incidence of decreased saliva production was 17.3% (54 out of 313). A total of 40 of the 54 patients completed further examinations, and definite or probable SS was diagnosed in 29 (9.3% of the original 313). Definite SS was diagnosed in six patients with interstitial pneumonia, three with bronchiolitis, three with sarcoidosis, and five with other diseases.
The prevalence of decreased saliva production and SS without obvious symptoms of dryness was high among patients with diffuse lung disease. In these patients, it is important to screen for SS, even if symptoms are not apparent.