Steroids Improve Length Of Walking Ability in Duchenne MD

COLUMBUS, Ohio, May 8 -- Boys with Duchenne muscular dystrophy are able to walk more than three years longer if they take daily corticosteroids, according to researchers here.

Their risk of scoliosis -- and the degree of curvature if it occurs -- is also sharply reduced, according to Wendy King, a physical therapist in the neurology department at Ohio State University.

On the other hand, the boys face a significantly increased risk of vertebral and long-bone fractures, King and colleagues reported in the May 8 issue of Neurology.

Previous studies have shown that corticosteroids improve strength and function in boys with the X-linked recessive disorder, but this is the first to look at the long-term impact of the drugs, King said.

The researchers examined medical records of 143 Duchenne patients treated at Ohio State from 2000 through 2003. Of those, 75 boys (52.4%) had been on daily steroids for at least a year, while the remaining 68 had never been treated with steroids or had been treated for less than six months.

The reason for non-treatment with steroids was invariably parent refusal because of fear of side effects, the researchers said. The average duration of steroid use was 8.04 years.

The study found:

• Boys on steroids were able to walk independently, on average, 3.3 years longer than those who weren't treated. The difference -- from 9.21 years to 12.52 years -- was significant at P<0.0001.
• The prevalence of scoliosis in the treated boys was 31%, compared with 91% among those not getting steroids, a difference that was significant at P<0.0001.
• The average scoliotic curve was 11.6 degrees in the treated boys, compared with 33.2 degrees in the untreated boys, which was also significant at P<0.0001.
• On the other hand, 32% of the treated boys had vertebral compression fractures versus none in those not getting steroids, which was significant at P<0.0012.
• The yearly long-bone fracture rate was 0.088 among the treated boys, but only 0.033 in the untreated group, difference by a factor of 2.6, which was significant at P<0.0032.

Several factors probably play a role in the increased rate of long-bone fractures, the researchers said, including prolonged independent walking and increased body weight because of the steroids.

The researchers noted that because of the orthopedic implications of steroids use, patients should also be prescribed calcium supplements and given regular bone density examinations at intervals of six months to two years.

"The role of bisphosphonates and other bone-sparing agents in this population remains to be determined," they said.

Despite the "unequivocal benefit" of corticosteroids, King and colleagues said, the side effects pose a significant risk that must be taken into account by physicians and parents.

"The benefits of steroids come at a cost of the side effects, and patients and parents need to weigh the benefits and risk of steroid treatments in order to make an informed decision," King said.