High-resolution CT and pulmonary function tests in rheumatoid arthritis patients with subclinical interstitial lung disease in Kuwait

BackgroundInterstitial lung disease (ILD) is a frequent extra-articular manifestation of RA and can cause significant morbidity and mortality.Aim of the workTo characterize and define the frequency of radiological and functional abnormalities capable of identifying “subclinical” RA-ILD with particular concern to the effect of methotrexate (MTX) therapy.Patients and methodsSixty patients with RA were recruited with no respiratory manifestations. They were classified into two groups: group 1 included 35 patients receiving MTX and group 2 included 25 patients receiving only nonsteroidal anti-inflammatory drugs. Patients were also classified according to chest high resolution CT (HRCT) as RA-ILD or RA-noILD. Pulmonary function test (PFT) abnormalities were also used to further characterize occult respiratory defects.Results38.3% of RA patients had subclinical ILD (25% in group 1 and 13.3% in group 2), while 61.7% were RA-no ILD. The percentage of patients with RA-ILD was insignificantly more in group 1 than group 2 (42.9% and 32% respectively). HRCT score revealed minimal to mild involvement in both groups. Long-standing RA with mean articular duration >50 months carries a significant risk for ILD. Other variables as age, gender, smoking, disease activity or rheumatoid factor seropositivity were not significant risk factors for development of RA-ILD.ConclusionsLung involvement should always be considered in patients with RA particularly those on MTX therapy even in the absence of chest symptoms. A tight control by PFTs, chest radiography and/or HRCT is necessary. Further studies evaluating the potential effect of MTX on progressive ILD with RA are needed.