LUNG-FUNCTION AND DIFFUSING-CAPACITY FOR CARBON-MONOXIDE IN PATIENTS WITH JUVENILE CHRONIC ARTHRITIS - EFFECT OF DISEASE-ACTIVITY AND LOW-DOSE METHOTREXATE THERAPY

Objective. We measured lung function, in terms of lung volumes, forced expiratory flow-volume curves and diffusing capacity of carbon monoxi de (DLCO), in a group Of 61 patients with juvenile chronic arthritis ( 42 female; age range 5 to 33 years) to ascertain whether disease activ ity and treatment with low dose methotrexate (MTX) influenced these pa rameters. The whole population was divided into subgroups based on ons et type (systemic, n=27; pauciarticular; n=12, polyarticular, n=22), d isease activity (active, n=42; inactive, n=19), and MTX treatment (tre ated, n=27; not treated n=34). Results. We found that maximal-mid expi ratory flow (MMEF) was significantly reduced inpatients with active di sease (p<0.025). The mean DLCO value, expressed as a percentage of the predicted value, and DLCO corrected for the hemoglobin value were low er than expected (67% and 80%, respectively). Multiple regression anal ysis showed that the forced vital capacity (FVC), forced expiratory fl ow in one second (FEV(1)) and DLCO were all correlated to the clinical subtype of the disease (p<0.05, p<0.02, p<0.02, respectively), and MM EF was related to disease activity (p<0.025). There was no evidence of any effect of MTX treatment on the pulmonary parameters. Conclusion. This study confirms that JCA is characterized by an impairment of lung function, mainly involving the small airways, and by interstitial dam age. These changes are related to the clinical subtypes of the disease and to disease activity.