Lung function abnormalities and respiratory muscle weakness in children with juvenile chronic arthritis

In contrast to adult rheumatoid arthritis (RA) little is known about the pr evalence, nature and cause of lung function abnormalities in children with juvenile chronic arthritis (JCA). The aim of this study was to determine wh ether children with polyarticular and systemic onset JCA have lung function abnormalities and if so, whether they are related to pulmonary disease, th oracic and/or muscular involvement. We determined lung function and disability in 31 children with polyarticula r and systemic JCA. Respiratory muscle function, thorax expansion and spine mobility were determined in the same patients, as well as in 32 matched he althy children. Peak expiratory flow (PEF) and forced vital capacity (FVC) were significant ly reduced in JCA patients, when compared to reference values. Thorax expan sion and spine mobility were normal, compared to paired controls. Maximum i nspiratory (PI,max) and expiratory (PE,max) pressures were significantly re duced in patients compared to paired control subjects. A positive correlati on was found between PE,max and FVC and PEF, an inverse correlation between expiratory pressure and disability. In conclusion, children with polyarticular and systemic juvenile chronic ar thritis show a pronounced impairment in respiratory muscle strength, severe enough to cause mild lung function abnormalities and an increase in disabi lity-scores.