Background Pulmonary involvement is a recognized extra-glandular manifestation of primary Sjögren's syndrome (pSS). Recently, we demonstrated that chronic obstructive pulmonary disease (COPD) is common in patients with pSS, even in the absence of smoking (1).
Objectives In a nested case control study, we now investigate the predictive role of obstructive airway symptoms for development of pSS.
Methods In two population-based surveys [Malmö Preventive Medicine (N=33346) and Malmö Diet & Cancer (N=30447), pulmonary function tests were performed. OAS was defined as either COPD (FEV1 <70% at inclusion) or a history of treatment of asthma/chronic bronchitis. Among survey participants, 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. Proportions with vs without a history of OAS or current smoking at inclusion in the health survey in pre-pSS individuals and controls were compared using χ2-test. The impact of OAS and smoking history on the risk of pSS was examined in conditional logistic regression analysis.
Results Sixty-three individuals (8% male, median age at inclusion 51 (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%. At inclusion significantly more pre-pSS individuals had OAS compared to controls: 21% vs 8%, p=0.014. OR 3.1 (95% CI 1.3-7.5). While in healthy controls there was a clear association between current smoking and OAS (p=0.031), in pre-pSS individuals smoking did not influence the presence of OAS (p=0.45). In multivariate analysis, OAS and being non-smoker independently predicted development of pSS during follow-up.
Conclusions Presence of obstructive airway symptoms in pre-pSS individuals increases the risk of pSS independently of smoking habits, while being current smoker seems to lower it. These data confirm results from our earlier cross-sectional and retrospective studies, both with regard to COPD and smoking (1,2). Airway inflammation, unrelated to smoking, may be a very early step in the development of pSS.
Nilsson A. et al, J Rheumatol 2015; Jan 15. pii: jrheum.140370. [Epub ahead of print],
Manthorpe R. et al. Ann Rheum Dis 2000; 59: 54-60
Disclosure of Interest None declared
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