Steroid myopathy in patients with chronic respiratory diseases

Corticosteroid-induced myopathy is a well known clinical entity, and experimental studies showed decreased rate of protein synthesis and increased rate of protein breakdown in muscles of chronically treated animals.

The present observational study was aimed to evaluate skeletal muscle functions in asthmatics and patients with other chronic respiratory diseases treated by inhaled or oral corticosteroids.

Thirty six patients with respiratory diseases were included into the study. The physician-rated peripheral motor deficits scale, stepper test and ankle/wrist index were used for assessment of muscle functions. The effects of length of glucocorticoids intake on muscle functions were evaluated.

Sixty five per cent of patients using corticosteroids daily during 1 year and longer reported weakness in legs, and 20% of these patients demonstrated objective signs of the muscle weakness. The performance on the stepper test was significantly worse in patients chronically using corticosteroids in comparison with the control group (10.9 ± 3.4 steps vs 16.1 ± 2.4 steps per 10s, respectively; F=21.6, p<0.001). In addition, a proportion of patients using corticosteroids for at least 18 months were characterized by muscle hypotrophy at a dominant leg.

Chronic intake of inhaled corticosteroids induces clinically significant decrease of muscle functions at least after 1-year of daily treatment.