- Background: A high incidence of abnormal pulmonary function tests has been reported in cross-sectional studies among patients with rheumatoid arthritis. Few patients have been enrolled in longitudinal studies. Objectives: To perform PFT in rheumatoid arthritic patients without pulmonary involvement and to identify variables related to changes in PFT over 5 years of follow-up. Methods: Consecutive RA patients underwent PFT according to recommendations of the American Thoracic Society. All surviving patients were advised to repeat the examination 5 years later. Results: PFT was performed in 82 patients (21 men, 61 women). Their mean age was 55.7 (15.9) years and the mean RA duration was 11.1 (10) years. Five years later 15 patients (18.3%) had died. Among the 67 surviving patients, 38 (56.7%) agreed to participate in a follow-up study. The initial PFT revealed normal PFT in only 30 patients (36.6%); an obstructive ventilatory defect in 2 (2.4%), a small airway defect in 12 (17%), a restrictive ventilatory defect in 21 (25.6%), and reduced DLco in 17 (20.7%). Among the 38 patients participating in the 5 year follow-up study, 8 developed respiratory symptoms, one patient had a new obstructive ventilatory defect, one patient developed a restrictive ventilatory defect, and 5 patients had a newly developed small airway defect. The DLco had improved in 7 of the 8 patients who initially had reduced DLco, reaching normal values in 5 patients. Over the study period a new reduction in DLco was observed in 7 patients. Linear regression analyses failed to identify any patient or disease-specific characteristics that could predict a worsening in PFT. The absolute yearly decline in forced expiratory volume in 1 sec among our RA patients was 47 ml/year, a decline similar to that seen among current smokers. Conclusions: Serial PFT among patients with RA is indicated and allows for earlier identification of various ventilatory defects. Small airways disturbance was a common finding in our RA patients.