Comparison of Pulmonary Function Decline in Steroid-Treated and Steroid-Naive Patients with Duchenne Muscular Dystrophy

Objective To describe and compare the lung function decline in patients with Duchenne muscular dystrophy on glucocorticoid therapy in contrast with glucocorticoid-naive patients, and to define the deciles of pulmonary decline in glucocorticoid-treated patients. Study design This retrospective study examined lung function of patients with Duchenne muscular dystrophy over 6 years of age followed between 2001 and 2015 at 2 centers-glucocorticoid-treated patients in Cincinnati, Ohio, and glucocorticoid-naive patients in Paris, France. Forced vital capacity (FVC, FVC%), forced expiratory volume in 1 second, maximal inspiratory pressure, maximal expiratory pressure, and peak expiratory flow data were analyzed. Only FVC data were available for the French cohort. Results There were 170 glucocorticoid-treated patients (92%), 5 patients (2.7%) with past glucocorticoid use, and 50 French glucocorticoid-naIve patients. The peak absolute FVC was higher and was achieved at earlier ages in glucocorticoid-treated compared with glucocorticoid-naive patients (peak FVC, 2.4 +/- 0.6 L vs 1.9 +/- 0.7 L; P < .0001; ages 13.5 +/- 3.0 years vs 14.3 +/- 2.8 years; P = .03). The peak FVC% was also higher and was achieved at earlier ages in glucocorticoid-treated patients (peak FVC%, 105.1 +/- 25.1% vs 56 +/- 20.9%; P < .0001; ages 11.9 +/- 2.9 years vs 13.6 +/- 3.2 years; P = .002). Rates of decline for both groups varied with age. Maximal rates of decline were 5.0 +/- 0.26% per year (12-20 years) for glucocorticoid-treated and 5.1 +/- 0.39% per year for gluco-corticoid-naive patients (11-20 years; P = .2). Deciles of FVC% decline in glucocorticoid-treated patients show that patients experience accelerated decline at variable ages. Conclusions These data describe nonlinear rates of decline of pulmonary function in patients with Duchenne muscular dystrophy, with improved function in glucocorticoid-treated patients. FVC% deciles may be a useful tool for clinical and research use.