Skeletal maturation is significantly delayed in boys with glucocorticoid-treated Duchenne muscular dystrophy (DMD) and is a factor that should be accounted for in the care of these patients, according to study results published in the International Journal of Pediatric Endocrinology.
Previous studies have reported an increased risk for fractures among boys with DMD, with a significantly increased risk in those treated with glucocorticoids. Glucocorticoid-treated patients with DMD may have considerably delayed bone maturation, and this delay in skeletal maturation increases with age. The goals of the current study were to explore the extent of delayed bone age in these patients and to assess how this delay may be related to short stature and low bone density.
The study included 62 patients (mean age, 11.0 years) with confirmed DMD from the Norwegian DMD cohort study. Both glucocorticoid-treated and glucocorticoid-naive patients underwent clinical examinations, laboratory investigations, radiography of the left hand and wrist, and dual-energy x-ray absorptiometry scanning.
Short stature, defined as a height below the 5th percentile, was documented in 31 of 59 boys (52.5%) with available height measurements. Statistical analysis showed a significant difference in height percentiles between glucocorticoid-naive and glucocorticoid-treated patients. Pubertal delay was common in glucocorticoid-treated patients, whereas glucocorticoid-naive boys had normal pubertal development.
This difference in height between glucocorticoid-naive and glucocorticoid-treated patients was no longer significant after correction for skeletal maturation, indicating that shorter stature in patients treated with glucocorticoids was related to delayed bone age.
Differences in bone mineral density (BMD) z scores between glucocorticoid-naive and previously glucocorticoid-treated patients could not be determined because of the small number of patients with available data. Mean BMD z scores dropped below -2 shortly before 12 years of age in patients treated with glucocorticoids. Low BMD z scores were significantly correlated with advanced age, long duration of glucocorticoid treatment, and immature Tanner stage but not with ambulatory status.
The lowest z scores were noted for the boys with the most severe skeletal delays. For glucocorticoid-treated patients, a significant increase in BMD z scores was noted after chronological age was corrected for skeletal delay, indicating that if skeletal delay is not considered in the evaluation of BMD z scores, there is potential for underestimation of z scores.
The study had several limitations, including the use of different measurement methods, possible measurement error because of lower limb contractures and lumbar lordosis, and lack of information on familial short stature.
“Our results revealed a significant delay in skeletal maturation in this patient group. The delay increased with age and duration of [glucocorticoid] treatment, and for some boys the delay was up to several years,” concluded the researchers. “Considering skeletal delay in the evaluation of growth…is imperative in the evaluation of bone health and decision-making concerning short stature and fracture risk of [glucocorticoid-treated] boys with DMD.”
Annexstad EJ, Bollerslev J, Westvik J, et al. The role of delayed bone age in the evaluation of stature and bone health in glucocorticoid treated patients with Duchenne muscular dystrophy. Int J Pediatr Endocrinol. 2019;2019:4.