Cigarette smoking in primary Sjögren's syndrome: positive association only with ANA positivity

Smoking is well known to contribute to the pathogenesis and severity of some systemic autoimmune rheumatic diseases and especially to the production of certain autoantibodies. Primary Sjögren's syndrome (pSS) is an autoimmune disease, affecting primarily the exocrine glands. It may also cause extraglandular involvement in some cases. In this study, we aimed to determine the frequency of smoking habits in our cohort of pSS patients and to investigate whether the frequencies of autoantibody positivity and extraglandular involvement were significantly different between patients with and without smoking. In this cross-sectional study, 207 patients with pSS (F/M 203/4), fulfilling the United States-European Consensus Criteria, and 602 healthy controls (F/M 534/68) were included. Patients and controls were classified into five groups: never smokers, current smokers, former smokers; ever smokers, and passive smokers. The χ(2) and Kruskal-Wallis tests were used for statistical analysis; a p value of less than 0.05 was accepted as statistically significant. While the frequency of current smokers was significantly lower in the pSS group compared with the healthy controls (11.6 vs 22.3%), the frequencies of former smokers (30.4 vs 11.8%), ever smokers (42.0 vs 34.1%), and passive smokers (47.3 vs 37.5%) were significantly higher in the pSS group compared with the healthy controls. In pSS patients, only antinuclear antibody (ANA) positivity was significantly associated with smoking habits, while there was no significant association with other autoantibodies or with the presence of extraglandular involvement. We found that in pSS patients smoking was significantly associated only with ANA positivity. Unlike the deleterious effects of smoking upon disease severity and anti-cyclic citrullinated protein (CCP) antibody production in rheumatoid arthritis, we could not find any association of smoking with extraglandular involvement and/or anti-Ro/anti-La antibody positivity in pSS. These results are indeed in line with the limited number of previous studies reported in the literature. Further studies with higher numbers of pSS patients are required to confirm the seemingly negative association of smoking with pSS.