PULMONARY-FUNCTION TESTS IN PATIENTS RECE IVING LONG-TERM LOW-DOSE METHOTREXATE

Long-term low-dose methotrexate (MTX) has a proven beneficial effect i n patients with rheumatoid arthritis; the main drawback being the risk of interstitial pneumonia. Although estimations have varied, in our r ecent prospective analysis we observed 4 cases among 124 receiving MTX for rheumatological disorders, ie. a risk rate of 3.2 %. Age,sex, dis ease duration, administration route and daily or cumulative dose do no t appear to affect risk, but recent work suggest that renal failure, c oncomitent use of nonsteroid anti-inflammatory drugs, smoking, past pu lmonary history or radiographic anomalies as well as recent withdrawal of corticosteroids are risk factors. Pulmonary function tests can be used to detect acute disorders and regular testing has been proposed t o help predicted pulmonary complications in patients receiving long-te rm MTX Unfortunately, minimal variations observed to date, for example in forced vital capacity or expiratory volume, do not appear to occur prior to clinical manifestations and may be due to normal aging proce sses or the pathological effect of the rheumatoid disease itself. In a ddition, due to the proven efficacy of MTX randomized trials against a control group not given MTX would be ethically unacceptable We are th us still unable to predict development of secondary pulmonary complica tions to long-term low-dose MTX We therefore recommend testing pulmona ry function at treatment onset to establish a reference for subsequent tests performed in case of clinical manifestations during MTX therapy . Patients should be counselled to consult in case of pulmonary sympto ms in order to allow diagnosis as early as possible. The most recent d ata also would suggest that MTX may induce infraclinical alterations o f pulmonary function although their significance remains to be clarifi ed.