The Relationship between Obesity and Clinical Outcomes in Young People with Duchenne Muscular Dystrophy

Abstract

Background: Duchenne muscular dystrophy (DMD) is a severe X-linked neuromuscular disorder. Young people with DMD have high rates of obesity. There is emerging evidence that a higher BMI may negatively affect clinical outcomes in DMD. This study aimed to explore the relationship between obesity and clinical outcomes in DMD. Methods: This was a retrospective clinical audit of young people (two–21 years) with DMD. Height and weight were collected to calculate BMI z-scores to classify obesity, overweight and no overweight or obesity (reference category). Cox proportional hazards models determined the impact of obesity at five to nine years on clinical milestones including time to: loss of ambulation, timed function test cut-offs, obstructive sleep apnoea (OSA) diagnosis and first fracture. Results: 158 young people with DMD were included; most (89.9%) were steroid-treated. Mean follow-up was 8.7 ± 4.7 years. Obesity prevalence increased from age five (16.7%) to 11 years (50.6%). Boys with obesity at nine years sustained a fracture earlier (hazard ratio, HR: 2.050; 95% CI: 1.038–4.046). Boys with obesity at six to nine years were diagnosed with OSA earlier (e.g., obesity nine years HR: 2.883; 95% CI: 1.481–5.612). Obesity at eight years was associated with a 10 m walk/run in 7–10 s occurring at an older age (HR: 0.428; 95% CI: 0.207–0.887), but did not impact other physical function milestones. Conclusions: Although 50% of boys with DMD developed early obesity, the impact of obesity on physical function remains unclear. Obesity puts boys with DMD at risk of OSA and fractures at a younger age. Early weight management interventions are therefore important.

Fracture risk and impact in boys with Duchenne muscular dystrophy: A retrospective cohort study

“…Functional assessments were analyzed over time for boys above 7 y, as consistent decline in motor performance is observed after this age. 17,21 These assessments included timed function tests (10 m walk/run, supine-to-stand and four stairs ascend) and Northstar Ambulatory Assessment (NSAA) scores for ambulatory boys, and EK2 scores for non-ambulatory boys.…”

Exploring caregivers' attitudes and beliefs about nutrition and weight management for young people with Duchenne muscular dystrophy

“…1,2 There is an increasing body of evidence that a higher body weight can worsen health and disease outcomes in individuals with DMD. This includes: negative consequences on respiratory function including obstructive sleep apnoea, 1,3,4 physical function, 5,6 bone fractures, 1 and metabolic complications such as dyslipidaemia, hypertension, and insulin resistance. [7][8][9] There are significant challenges in achieving and maintaining optimal weight status in the context of DMD.…”

“…Obesity affects up to 50% of children with DMD 1,2 . There is an increasing body of evidence that a higher body weight can worsen health and disease outcomes in individuals with DMD.…”

Pilot study of a virtual weight management program for Duchenne muscular dystrophy

“…Boys with Duchenne muscular dystrophy (DMD) who are treated with glucocorticoids ("steroids") show an increased prevalence of obesity, with one in two above a healthy weight by late childhood. [1][2][3] When compared to typically developing children, body mass index (BMI) is 1.0 kg/m 2 higher in males with DMD; and weight velocity appears to increase from age 7 years. 4 A complex range of factors contributes to weight gain including: long term steroid treatment and its effects on appetite and weight, reduced physical activity and consequently total energy expenditure due to progressive physical disability, 5 reduced resting energy expenditure, 6 and sleep disturbance and fatigue.…”

“…Boys with Duchenne muscular dystrophy (DMD) who are treated with glucocorticoids (“steroids”) show an increased prevalence of obesity, with one in two above a healthy weight by late childhood 1–3 . When compared to typically developing children, body mass index (BMI) is 1.0 kg/m 2 higher in males with DMD; and weight velocity appears to increase from age 7 years 4 .…”