Effect of long-term treatment with corticosteroids on skeletal muscle strength, functional exercise capacity and health status in patients with interstitial lung disease

Background and objectiveCorticosteroids are occasionally used in the treatment of ILD. Chronic corticosteroid administration induces skeletal muscle weakness. However, it is unclear whether chronic corticosteroid treatment could further reduce skeletal muscle strength in patients with ILD who are weaker than healthy controls. The aim of this study was to determine the effects of chronic corticosteroid administration on skeletal muscle strength, exercise capacity, activities of daily living (ADL) and health status in ILD patients. MethodsForty-seven ILD patients treated with corticosteroids and 51 Medical Research Council dyspnea grade-matched ILD patients not treated with corticosteroids were assessed by isometric quadriceps muscle force (QF) and handgrip force (HF), pulmonary function, 6-min walk distance, ADL score and health status (Medical Outcomes Study 36-Item Short-Form Health Survey), and the two groups' results were compared. ResultsQF and HF were significantly lower in subjects on corticosteroids than in the control patients (QF, 52.625.6 vs 77.1 +/- 33.3 %predicted, P<0.001; HF, 63.8 +/- 22.4 vs 81.8 +/- 28.3 %predicted, P<0.001, respectively). There were no significant differences in the 6MWD, ADL score and all subscales of the SF-36 between the groups. Inverse correlations were found between skeletal muscle strength and total amount of corticosteroids administered (QF, r=-0.401, P=0.005; HF, r=-0.403, P=0.005). On multiple regression analysis, the total amount of corticosteroids was an independent predictor of HF. ConclusionChronic cor3ticosteroid treatment contributes to muscle weakness in ILD patients, and muscle weakness is inversely correlated to the total amount of corticosteroids administered.