Observations of body mass index in Duchenne muscular dystrophy: a longitudinal study.
OBJECTIVE
Nutritional issues that are associated with Duchenne muscular dystrophy (DMD) remain poorly understood. The aim of this analysis was to describe and explore longitudinal observations of body mass index (BMI) in a cohort of children with DMD.


METHODS
Anthropometric and clinical characteristics were collected retrospectively and longitudinally for boys with DMD seen in two large neuromuscular clinics. BMI Z-scores were determined using the Centers for Disease Control and Prevention reference values for children (2000).


RESULTS
Medical records (n=193) were examined from which 75% were included for analysis. The mean age of the cohort at the time of data collection was 11.9 years, with 72% of patients currently or previously using steroids. The highest prevalence of obesity based on the BMI Z-score was 50% at the age of 10 years. Longitudinally, BMI Z-scores from the age of 2 to 12 years plot approximately one s.d. above the mean, after which there is a marked and progressive decline. BMI gainers were identified for whom BMI Z-score increased by 1.65 units compared with the 0.09 units in non-gainers. BMI gainers were younger when they had their first BMI measurement (5.9 vs 7.2 years), and this measure was significantly lower compared with the non-gainers (BMI Z-score: 0.04 vs 1.17). In this cohort, BMI was associated with age, ambulatory status and lung function.


CONCLUSIONS
This study demonstrates that boys with DMD using steroid therapy experience shifts in BMI. A declining BMI appears to be associated with increasing age. Interpretation of growth patterns is limited here by a lack of normative growth references in DMD.
1] Department Nutrition and Dietetics, Monash University, Melbourne, Victoria, Australia [2] Murdoch Childrens Research Institute, Melbourne, Victoria, Australia.
Z E
ZE
Davidson
1] Murdoch Childrens Research Institute, Melbourne, Victoria, Australia [2] Department of Neurology, The Royal Children's Hospital, Melbourne, Victoria, Australia.
M M
MM
Ryan
1] Murdoch Childrens Research Institute, Melbourne, Victoria, Australia [2] Department of Neurology, The Royal Children's Hospital, Melbourne, Victoria, Australia.
A J
AJ
Kornberg
Neurosciences Department, Royal Children's Hospital, Brisbane, Queensland, Australia.
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Sinclair
Neurosciences Department, Royal Children's Hospital, Brisbane, Queensland, Australia.
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A
Cairns
Department Nutrition and Dietetics, Monash University, Melbourne, Victoria, Australia.
K Z
KZ
Walker
Department Nutrition and Dietetics, Monash University, Melbourne, Victoria, Australia.
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H
Truby
D000293:Adolescent; D000367:Age Factors; D001823:Body Composition; D015992:Body Mass Index; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005938:Glucocorticoids / Q000009:adverse effects / Q000627:therapeutic use*; D006128:Growth; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D020388:Muscular Dystrophy, Duchenne / Q000188:drug therapy*; D063766:Pediatric Obesity / Q000453:epidemiology / Q000209:etiology*; D015995:Prevalence; D012016:Reference Values; D012189:Retrospective Studies; D013256:Steroids / Q000009:adverse effects / Q000627:therapeutic use*
D005938:Glucocorticoids; D013256:Steroids