Vertebral Fractures in Duchenne Muscular Dystrophy Patients Managed With Deflazacort

Abstract

Background: Corticosteroids are widely used in the management of patients with Duchenne muscular dystrophy (DMD). They improve quality of life in these patients by prolonging ambulation and preserving cardiorespiratory status. However, corticosteroid treatment is associated with a decrease in bone mineral density (BMD) and an increased risk of vertebral fractures (VF). The purpose of this study was to investigate the prevalence of VF in patients with DMD undergoing long-term treatment with the corticosteroid deflazacort.

Methods: We retrospectively reviewed 49 male patients with DMD on long-term deflazacort therapy at a single institution. All patients had received deflazacort for at least 2 years. VF prevalence, age at start of deflazacort treatment, duration of treatment, BMD Z-score and patient ambulatory status at the time of fracture were evaluated.

Results: Of the 49 patients on long-term deflazacort treatment, 26 had VF. Out of these patients who had VF, 19% showed evidence of VF in their third year of therapy, 50% within 5 years of starting therapy, 69% within 7 years of starting therapy, and 100% within 9 years. The first evidence of VF was observed at mean BMD Z-score, lumbar (L)=-2.2 and whole body (B)=-3.1. Eighty-five percent of these patients had at least 3 collapsed vertebrae. Mean BMD Z-score at the time of or before when multiple fractures were noted was -2.4 (L) and -3.4 (B). Patients who started deflazacort at age 3 to 5, 5 to 7 or 7 to 9 years developed a VF after a mean of 4.7, 5.4, or 5.7 years, respectively. Sixty-two percent of patients had VF by the age of 12 years and 91% of patients by age of 15 years. Twenty-one of 26 patients were ambulatory at the time of VF.

Conclusions: Our findings suggest that there is a high risk of VF associated with length of deflazacort use in DMD patients, regardless of age at start of therapy.

Level of evidence: Level III-retrospective therapeutic study.