To assess the prevalence of chronic obstructive pulmonary disease (COPD) in patients with primary Sjögren syndrome (pSS) and to study the association of COPD with cigarette smoking, radiographic features, respiratory symptoms, disease activity, and laboratory inflammatory and serological features in patients with pSS.
Fifty-one consecutive patients with pSS (mean age 60 yrs, range 29-82 yrs, 49 women) were assessed by pulmonary function tests (PFT). The PFT results were compared with previously studied population-based controls, standardizing results with regard to sex, age, height, weight, and cigarette smoking. In addition, patients with pSS were assessed by computed tomography of the chest, the European League Against Rheumatism Sjögren Syndrome Disease Activity Index and Patient Reported Index, the St. George's Respiratory Questionnaire (which evaluates respiratory symptoms), and by laboratory inflammatory and serological tests.
Forty-one percent of all patients with pSS and 30% of the never-smoking patients with pSS fulfilled the Global Initiative for Chronic Obstructive Lung Disease criteria for COPD. Vital capacity (VC), forced expiratory volume in 1 s (FEV1), FEV1/VC ratio, and DLCO were significantly decreased while residual volume (RV) and the RV/total lung capacity ratio were significantly increased in patients with pSS. Moderate correlations between PFT results, symptoms, and disease activity were found. However, laboratory inflammatory and serological features were poorly associated with PFT results in patients with pSS.
COPD was a common finding in patients with pSS, even among never-smoking patients. An obstructive pattern was the predominant PFT finding in patients with pSS, although a superimposed restrictive lung disease could not be excluded. The results suggest that the disease per se is involved in the development of COPD in pSS.