Pulmonary function in rheumatoid arthritis in a Tunisian population

BACKGROUND: The rheumatoid polyarthritis (PR) is a frequent pathology in Tunisia. The most frequent extra articular expression of this disease is in the respiratory tract. AIM: To determine the lung functional profile of PR of the Tunisian population by establishing possible relations between ventilatory variables and clinico-biological parameters of PR. METHODS: It is a cross sectional study which concerned 87 patients (77 women) having a confirmed PR. They benefited from a measure of the lung function by a total physical Plethysmography and by the technique of double transfer NO-CO. Clinical and biological checkup were realized. RESULTS: Three kinds of pulmonary function defects were found: obstructive ventilatory defect (13%), restrictive defect (7%) and mixed defect (1%). Ventilatory flows and the lung volumes correlated negatively with the inflammatory syndrome (p<0.05). Alveolar-capillary diffusion capacity (DLco) was altered in an isolated way or associated with the respiratory functional syndromes (obstructive and restrictive) (6%). This abnormality had a vascular origin with an isolated fall of the lung capillary volume (Vc), a membrane origin with an isolated fall of the diffusion membrane (DM) or a combined origin with the decline of Vc and DM. This latter case was found at a late stage of PR. 58% of PR patients had a normal pulmonary function. CONCLUSION: All these functional findings were linked to PR itself (inflammatory and auto-immune origin) or to the lung toxicity due to the treatment by Methotrexate (alveolar and bronchial damage).