Background Smokers have increased risk of anti-CCP positive RA. In some diseases, such as Ulcerative colitis, Sarcoidosis and Parkinson's disease smoking seems beneficial or protective. In 2000 we described an inverse association between smoking and focal sialadenitis and anti-Ro/anti-La in pSS (1)
Objectives To investigate the effect of smoking on development of pSS in a nested case control study, based on two prospective health surveys.
Methods Among participants in two population-based surveys [Malmö Preventive Medicine (N=33346) and Malmö Diet & Cancer (N=30447)], incident cases of pSS were identified. Four controls for each validated case, matched for sex, year of birth and year of screening, who were alive and free of pSS when the index person was diagnosed with pSS, were selected from the corresponding health survey database. Information on the time of onset of sicca symptoms had been independently recorded at the time of pSS diagnosis. Proportions with a history of never/former/current smoking in pre-pSS individuals and controls were compared using the χ2-test. The impact of smoking history on the risk of pSS was examined in conditional logistic regression analysis.
Results Sixty-three individuals (8% male, mean age at inclusion 51 (range 29-72) years) were diagnosed with pSS a median of 98 months (3-329) after inclusion and fulfilled the 2002 AECC-criteria for pSS. ANA, RF, anti-Ro and anti-La were positive in 73%, 57%, 59% and 41% respectively. Focal sialadenitis with focus score ≥1 was found in 85%.
There was a significantly higher proportion of non-smokers among pre-pSS individuals compared to controls (85% vs 68%; p=0.004). Current smoking at inclusion was associated with a reduced risk of subsequent diagnosis of pSS (OR 0.26; 95% CI 0.11-0.60). The pattern of present–former–never smokers was different in cases and controls. The ratio present/former smoker was 0.3 among cases and 1.5 among controls (p<0.001). Being a former smoker was associated with an increased risk of pSS: OR 8.1; 95% CI 3.2-21 compared to current smokers. OR 4.1; 95% CI 1.8-10 compared to never smokers. Stopping smoking was not related to pSS symptoms (information available in 22 of 32 former smokers), as these appeared >5 years after smoking cessation in 91%. Anti-Ro or anti-La antibodies were found in similar frequencies among present, former and never smokers (80%, 56% and 56% respectively, p=0.28)
Conclusions Smoke cessation increases the risk of being diagnosed with pSS, while being a current smoker seems to lower it, confirming our former retrospective study. The impact of smoking and smoke cessation on development of autoimmunity should be further studied.
Manthorpe R et al. Lower frequency of focal lip sialadenitis (focus score) in smoking patients. Can tobacco diminish the salivary gland involvement as judged by histological examination and anti-SSA/Ro and anti-SSB/La antibodies in Sjogren's syndrome? Ann Rheum Dis 2000; 59: 54-60
Disclosure of Interest None declared