Cigarette smoking patterns preceding primary Sjogrens syndrome

Background Cigarette smoking is a well-established risk factor for several autoimmune diseases, but its role in primary Sjogrens syndrome (pSS) remains unclear. Here, we investigated the association between cigarette smoking and subsequent development of pSS. Methods Information on smoking habits was collected from lifestyle habit questionnaires of patients with pSS (n=815) and a matched control group (n=4425) for a case-control study. Differences in smoking exposure were analysed by conditional logistic regression. Potential interactions between smoking and risk-associated human leucocyte antigens (HLA) were assessed by multivariate regression. Results The fraction of patients with pSS having ever smoked prior to diagnosis was lower than in controls (OR 0.67, 95% CI 0.55 to 0.81). Current smoking at diagnosis was also less prevalent in cases (OR 0.37, 95% CI 0.26 to 0.53). However, period prevalence of smoking during early adulthood was not statistically different from controls (OR 0.89, 95% CI 0.66 to 1.22) but markedly decreased over time. This was partly due to patients being more prone to stop smoking, starting already 30 years prior to diagnosis (OR 2.01, 95% CI 1.22 to 3.30). Smoking patterns were also stratified by autoantibody status, yielding similar estimates. No interaction effects between HLA-DRB1 haplotypes and smoking were observed. Conclusion The observed smoking patterns indicate that individuals who develop pSS smoke equally much as the general population during early life but are then more prone to stop. The data can be interpreted as smoking conferring protective effects, or reflecting early symptoms of pSS that affect smoking habits, emphasising the slow, progressive development of the disease.Funding Agencies|Swedish Research CouncilSwedish Research Council; Swedish Rheumatism Association; King Gustaf the V:th 80-year foundation; Heart-Lung FoundationSwedish Heart-Lung Foundation; Freemasons in Stockholm Foundation for Childrens Welfare; Stockholm County CouncilStockholm County Council; Karolinska InstituteKarolinska Institutet; Torsten and Ragnar Soderberg Foundation; Science for Life Laboratory; Swedish Research Council (VR-RFI)Swedish Research Council; Uppsala University; Knut and Alice Wallenberg FoundationKnut & Alice Wallenberg FoundationArtikeln har två poster i Web of Science: 000576792500007 och 000578591000003 /2020-10-30