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Eur Respir J 1907; 10:1072-1078 Printed in UK - all rights reserved Copyright ©ERS Journals Ltd 1997 European Respiratory Journal ISSN 0903 - 1936 Airway obstruction and rheumatoid arthritis A. Vergnen6gre*, N. Pugnere**, M.T. Antonini*, M. Arnaud**, B. Melloni**, R. Treves**, F. Bonnaud** Airway obstruction and rheumatoid arthritis. A. Vergnenkgre, N. Pugnere, M.T. Antonini, M. Arnaud, B. Melloni, R. Treves, F. BonnaucL ©ERS Journals Ltd 1997. ABSTRACT: The aim of this study was to assess the percentage of respiratory disorders and airway obstruction in patients with rheumatoid arthritis by com- paring lung function test results between patients with rheumatoid arthritis and control subjects with other rbeumatological conditions. A prospective case-control study of respiratory symptoms and lung function abnormalities was performed in a series of 100 patients with rheumatoid arthri- tis. Eighty eight patients with other rbeumatological diseases served as controls. Diagnosis of respiratory disorders was based on clinical, radiological and spiro- metric findings. Airway obstruction was determined from predicted values. The results were compared using Student's t-test and Chi-squared tests. An explanao tory analysis was carried out by linear regression. The number of symptoms, respiratory disorders (including bronchiectasis) and lung function abnormalities was higher in patients with rheumatoid arthritis than in controls. After exclusion of smokers, the proportion of airway obstruction in patients with rheumatoid arthritis was 16% (versus 0% in controls), although the patients with rheumatoid arthritis still had more symptoms and respiratory dis- orders. The Chi-squared test did not identify any relationship between airway obstruction, duration of rheumatoid arthritis and type of treatment and occur- rence of Sj6gren's syndrome. In the nonsmokers, different explanatory models for the patients with and without a history of cardiac and respiratory disease emerged from multivariate analysis of indices of obstruction. These models included vari- ables characterizing the severity and course of the rheumatoid arthritis. Respiratory disorders (including bronchiectasis) and airway obstruction are more frequent among patients with rheumatoid arthritis than in rheumatological con- trois. Although the exact pathophysiology of the link between bronchial obstruc- tion and rheumatoid arthritis is still a matter of debate, explanatory factors for obstruction included variables characterizing the rbeumtoid arthritis. Eur Respir J 1997; 10: 1072-1078. *Medical Information Unit, Chest Disease Dept. **Chest Disease Dept, +Pulmonary Function Test Laboratory, and +*Rheamato- logic Unit, University Hospital, Limoges, France. Correspondence: A. Vergnen~:gre Unit6 d'Information M6dicale Service de Pneumologie H6pital Universitaire du Cluzeau 87042 Limoges France Keywords: Airway obstruction bmnchiectasis epidemiology rheumatoid arthritis Received: March 25 1996 Accepted after revision January 16 1997 A large number of studies have been devoted to pul- monary disorders in patients with rheumatoid arthritis (1~). The well-characterized disorders include: pleur- al effusions; rheumatoid nodules; pulmonary fibrosis; and Caplan's syndrome [1, 2]. Bronchiectasis and an in- creased incidence of chest infections have also been rep- orted [3, 4], but.the pathophysiology is largely unknown. Although abnormal airway function has been described in 30--40% of RA patients depending on the study [5-11], the existence of a specific airway obstruction is a sub- ject of debate [12]. The prevalence of abnormalities might be influenced by: 1) patient selection (if they were affected by inter- stitial lung disease, the incidence of abnormal pulmonary function test [9] could increase to 30-40%); 2) smok- ing habits [5]; 3) the methods used to demonstrate abnor- mal lung function: maximal mid-expiratory flow rate (MMEFR) [5, 6], maximum expiratory flow at 50% forced vital capacity (V'max 50) [8]. Unfortunately, there is, as yet, no universally agreed definition of what constitutes an abnormal result [11]. Among the case-control studies, some have compared pulmonary function between RA patients and controls with degenerative joint disease [5, 8, 13], although, in most of the studies, RA patients have been compared with controls in the general population [6, 7, 10, 11]. In the present study, we attempted to eliminate the smoking effect and we employed a standardized defin- ition of lung function abnormalities [14]. The study was designed to assess the percentage of respiratory disor- ders and airway obstruction in RA patients by compar- ing lung function between RA patients and those with other rheumatological diseases. Methods Study population Between January and December 1994, 100 consecu- tive patients with rheumatoid arthritis, as defined by the criteria of the American Rheumatoid Association (1987),