The relationship of bone mineral density and vitamin D levels with steroid use and ambulation in patients with Duchenne muscular dystrophy

The Relation Between Nutritional Intake and Weight in 4–18 Year Old Patients with DMD: What could possibly be done to prevent weight gain?

Background: Overweight is a common problem in Duchenne muscular dystrophy (DMD) and is associated with reduced mobility and quality of life. The influence of nutritional intake on (over)weight is unclear. Objective: To investigate weight and energy and macronutrients intake compared to age-specific requirements in DMD patients (4–18 years). Methods: We assessed weight and body mass index (BMI) and the amount of energy (kcal/day) and macronutrients based on self-reported nutrition diaries. Nutritional intake was compared to requirements for 3 age-groups according to the Dutch Healthy Diet Guideline (4–8/9–13/14–18 years) using a student’s t-test, and relations with age and BMI were investigated by means of Pearson’s correlations. Results: Forty-eight patients participated, 22 ambulatory, median age 10.8 years. The majority used corticosteroids (N = 41). Overweight (BMI z-score >  2.07) was present in 19 patients; 6% (4–8 years), 73% (9–13 years) and 47% (14–18 years). Overweight was more common in non-ambulatory (61.6%) than ambulatory patients (13.6%). Patients aged 4–8 received 290 kcal/day more than required (p <  0.001). Patients aged 9–13 received 349 kcal/day (p = 0.005) less than required. Overall, intake of fibre, nuts, meat/fish/eggs/legumes and dairy was lower than recommended (p <  0.05). The difference between energy intake versus requirement correlated moderately to age (r = –0.549, p <  0.001) and BMI (r = –0.562, p <  0.001). Conclusions: Overweight was found especially in patients aged 9–18 even though they received less energy than required. Younger patients (4–8) had good weight but consumed more energy than required. All patients did not consume enough fibre, nuts, meat/fish/eggs/legumes and dairy. Limiting energy and increasing fibre/protein intake at an early age may prevent overweight at a later age.

Bone Mineral Density Assessment by Quantitative Computed Tomography in Glucocorticoid-Treated Boys With Duchenne Muscular Dystrophy: A Linear Mixed-Effects Modeling Approach

OBJECTIVE

Boys with Duchenne muscular dystrophy (DMD) are at risk of bone damage and low bone mineral density (BMD). The aim of the study is to examine lumbar BMD values measured by QCT and identify the factors associated with BMD loss using a multilevel mixed-effects model.

METHODS

Lumbar BMD was evaluated by quantitative computed tomography (QCT) at diagnosis, 1 and 2 years follow up in patients with DMD who were treated with GC. Demographic data, functional activity scores (FMSs), laboratory parameters and steroid use were recorded. A multilevel mixed-effects model was used to analyze BMD loss.

RESULTS

Nineteen patients with DMD who had a total of sixty complete records between January 2018 and October 2021 were retrospectively analyzed. At baseline, 15.8% of patients (3/19) had low lumbar BMD (Z score ≤ -2), and the mean BMD Z score on QCT was -0.85 (SD 1.32). The mean BMD Z score at 1 and 2 years postbaseline decreased to -1.56 (SD 1.62) and -2.02 (SD 1.36), respectively. In our model, BMD Z score loss was associated with age (β=-0.358, p=0.0003) and FMS (β=-0.454, p=0.031). Cumulative GC exposure and serum levels of calcium, phosphorus, 25(OH)-vitamin D and creatinine kinase did not independently predict BMD loss.

CONCLUSIONS

This study demonstrates that in DMD patients, lumbar BMD decreased gradually and progressively. Age and FMS are the main contributors to BMD loss in boys with DMD. Early recognition of risk factors associated with BMD loss may facilitate the development of strategies to optimize bone health.

Cessation of ambulation results in a dramatic loss of trabecular bone density in boys with Duchenne muscular dystrophy (DMD)

Glucocorticoids are currently used to improve muscle strength and prolong ambulation in boys with DMD although the effect on bone health is still unclear. The aim of this study was to compare bone strength in healthy children and boys with DMD and investigate the interaction between diminished muscle function, loss of ambulation and high dose oral steroids, over a two year time frame. Fifty children were studied, 14 healthy boys (HB), 13 boys with DMD who remained ambulant (DMD-RA) and 23 boys with DMD who lost ambulation (DMD-LA). All boys with DMD had taken oral glucocorticoids. Peripheral quantitative computed tomography was used to measure bone geometry, density, strength and muscle mass of the non-dominant tibia and radius. Measurements were made at baseline, 12 and 24 months at the distal metaphysis and mid diaphysis sites. Differences between the three groups were evaluated using ANOVA and a repeated measures model. There were no significant differences in age between the groups: mean age was 9.4, 8.7 and 8.8 years for HB, DMD-RA and DMD-LA, respectively. There was no significant difference in steroid exposure between the DMD groups. However, boys who lost ambulation had significantly lower muscle function at baseline (North Star Ambulatory Assessment DMD-RA 23.6 vs. DMD-LA 18.8; p < 0.05). At baseline, healthy boys had significantly greater trabecular bone density at the distal radius /ulna (23%/27%) and distal tibia/fibula (30%/46%) than boys with DMD (p < 0.05). They also had significantly larger diaphyseal tibiae/fibulae (74%/36%) and radii/ulnae (49%/31%) with thicker corticies and consequently greater bone strength. In contrast, boys with DMD had greater cortical density (4%). Over time, there were small significant differences in the rate of change of both muscle and bone parameters between healthy boys and boys with DMD. For both ambulant and non-ambulant boys with DMD the greatest changes in cortical bone were evident at the tibia. After two years boys with DMD had on average, 63% less bone strength than healthy boys. However, the most strikingly significant difference was in trabecular bone density for boys who became non-ambulant. By 2 years non-ambulant DMD boys had 53% less trabecular bone density at distal tibia than their healthy age matched peers compared with boys who remained ambulant who had 27% less trabecular bone density. In conclusion, bone and muscle strength is reduced for all boys with DMD even while they remain ambulant. However, tibia trabecular bone density loss is significantly accelerated in DMD boys who lose independent ambulation compared to DMD boys who remain ambulant despite equivalent levels of corticosteroid exposure.