The Science Journal of the American Association for Respiratory Care

2006 OPEN FORUM Abstracts

IMPROVED PULMONARY FUNCTION IN BOYS WITH DUCHENNE MUSCULAR DYSTROPHY WHEN DEFLAZACORT IS STARTED IN THE FIRST OR SECOND DECADE

Yang  L, RRT,   Phan T, RRT, BSc., Harris VA, RN,  Biggar WD, MD

Bloorview Kids Rehab, 150 Kilgour Road, Toronto, Ontario, Canada,  M4G 1R8. University of Toronto, Toronto, Ontario, Canada.

Background. Duchenne muscular dystrophy (DMD) is a recessive X-linked inherited disorder affecting skeletal, cardiac, and pulmonary function primarily. Boys usually die in their late teens to twenties from cardio-respiratory complications. Corticosteroids offer the best method of preserving muscle function. Deflazacort is an oxazolone derivative of prednisone. We wanted to compare the effect on pulmonary function when deflazacort is started before 8 years of age and after 10 years of age. Method. The pulmonary function of three groups of boys with DMD was compared: G-1 was treated with daily deflazacort from 5-8 years of age (n=40), G-2 started treatment between 10-16 years of age (n=16), and G-3 was not treated (n=34). Boys were followed every 4-6 months by the same multidisciplinary team and the same clinical protocol. Results. Without deflazacort treatment, FVC-pp normally declines after 9-10 years of age. At 10 years, the FVC-pp for G-1 was 94±13% and G-3 was 65±13% (p<.005). At 18 years, the FVC-pp for G-1 was 81±13% and G-3 was 34±10% (p<.005). When deflazacort was started in the second decade and continued for more than 2 years (G-2), FVC-pp was better than boys in G-3 but less than boys in G-1 at the same age. Three boys started deflazacort at 20-22 years of age with a 5-10% improvement in FVC-pp and fewer symptoms of dyspnea. By 18 years, 15 of 34 boys in G-3 required nocturnal BiPAP and 0 of 40 in G-1.  Twelve of 34 boys in G-3 died of cardiopulmonary complications (mean 17.6±1.7 years) and 2 of 40 in G-1 died of cardiac failure at 13 and 18 years of age. The boys in G-1 were significantly shorter. They did not have excessive weight gain or an increased susceptibility to infection and 22 of 40 had asymptomatic cataracts that did not require treatment. Conclusion. Pulmonary function is significantly improved and mortality reduced by deflazacort treatment and is associated with few side effects. Preservation of pulmonary function is greatest when deflazacort treatment is started when the boys are young and have normal FVC-pp.

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