Steroids Prevent Scoliosis in Duchenne Muscular Dystrophy

Abstract

Source: Lebel DE, Corston JA, McAdam LC, et al. Glucocorticoid treatment for the prevention of scoliosis in children with Duchenne muscular dystrophy: long-term follow-up. J Bone Joint Surg. 2013; 95(12): 1057– 1061; doi: 10.2106/JBJS.L.01577Investigators from the University of Toronto sought to determine if the long-term use of glucocorticoids in patients with Duchenne muscular dystrophy (DMD) resulted in a decreased incidence and progression of scoliosis and a decreased need for spinal surgery. Boys between ages 7 and 10 years with a diagnosis of DMD who were able to walk were enrolled in the study. The treatment group consisted of study participants whose parents consented to corticosteroid treatment; the control group consisted of boys whose parents elected not to use corticosteroids. The boys in the treatment group received once-daily oral deflazacort at a dose of 0.9 mg/kg per day. Study patients were followed every 4 to 6 months with a physical examination, pulmonary function testing, and radiographs. An ophthalmologist performed an annual eye examination to assess for development of cataracts. Physiotherapy and orthotic treatment was the same for both groups. Participants were prescribed bisphosphonates to prevent glucocorticoid-induced osteoporosis. Spine radiographs for scoliosis were obtained once the patients stopped walking and began using a wheelchair. The investigators calculated the rate of avoiding spinal surgery between the study groups after 15 years and compared the rate of side effects between groups.Overall, 54 boys with DMD were enrolled in the study, including 30 in the treatment group and 24 controls. The study groups did not differ with respect to age, pulmonary function, weight, height, or physical function at the time of enrollment. Five boys (21%) in the nontreatment group and 1 boy (3%) in the deflazacort treatment group died during the study (P < .005) of pulmonary or cardiac complications related to DMD. No patients in the glucocorticoid group developed scoliosis after 10 years of deflazacort treatment. After 15 years of follow-up, the rate of avoiding surgery among survivors was 78% (95% CI, 57%–89%) in the treatment group and 8.3% (95% CI, 0.8%–28%) in the nontreatment group. Patients in the treatment group showed significantly better pulmonary function, were able to walk independently longer, and maintained the ability to climb a flight of stairs without assistance for a mean of 1.5 years longer time.Side effects in the treatment group included cataracts in 21 treatment group patients (70%). However, only 2 patients required cataract surgery because of decreased visual acuity. There was no difference in fracture rate between the 2 groups. None of the boys developed symptomatic osteonecrosis.The authors conclude that the use of glucocorticoids in DMD leads to a significant decrease in the rate of spinal surgery for scoliosis.Dr Hennrikus has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device.The results of this important study clearly demonstrate that daily deflazacort prolongs life, delays deterioration of pulmonary function, and decreases the development of scoliosis and the need for spine surgery in patients with DMD. The current study is the longest continual follow-up of a cohort of patients with DMD treated with glucocorticoids and is a continuation of interim results that the authors reported in 2004.1After 15 years of follow-up, glucocorticoids had a long-term protective effect against the development of scoliosis. Only 20% of patients treated with deflazacort developed scoliosis and needed spinal surgery compared with 92% of nontreated patients. In addition, the curves in the patients treated with glucocorticoids stabilized after skeletal maturity showing that deflazacort therapy prevented the need for scoliosis surgery in the long term. The current study has a few limitations. Deflazacort, an oxazolone derivative of prednisone, available in Canada and Europe, is not approved by the US Food and Drug Administration for use in the United States. Secondly, the threshold for surgical treatment in the current study was a Cobb angle of 20 degrees. Other studies have used 35 degrees as a surgical indication.2,3 The differences between the 2 treatment groups in the current study may have changed if the authors used a 35-degree threshold for surgery. Lastly, the study was not randomized. Families that saw more physical deterioration in their child may have decided against the use of deflazacort. This would have resulted in the selection of less severely affected boys in the treatment group. Despite these limitations, this excellent study offers long-term prospective data that pediatricians can use to encourage all families of boys with DMD to strongly consider corticosteroid therapy.