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Measurements of Motor Function and Other Clinical Outcome Parameters in Ambulant Children with Duchenne Muscular Dystrophy
Published on: January 12, 2019
Pulmonary dysfunction in children with Duchenne muscular dystrophy may occur earlier than we thought - analysis using
Eliza Wasilewska1, Sylwia Małgorzewicz2, Jarosław Meyer-Szary3
1Department of Pulmonology and Allergology, Medical University of Gdansk, Poland.
Insights
Pulmonary function in Duchenne muscular dystrophy (DMD) patients declines earlier than previously thought, especially in non-ambulatory and non-steroid users. Early intervention and monitoring are crucial for managing respiratory health in DMD.
Area of Science:
- Pediatric Pulmonology
- Neuromuscular Disorders
- Clinical Research
Background:
- Respiratory compromise is a primary determinant of survival in Duchenne muscular dystrophy (DMD).
- Accurate assessment of pulmonary function is vital for managing DMD patients.
- The z-score method offers a standardized approach to evaluating pulmonary function across different age groups.
Purpose of the Study:
- To evaluate pulmonary function in DMD patients using z-scores.
- To identify factors influencing pulmonary function decline in DMD, independent of disease progression.
Main Methods:
- Spirometry was performed on 55 DMD boys (aged 5-18 years), measuring forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and peak expiratory flow (PEF).
- Data included absolute values, percent predicted values (%pv), and z-scores.
- Information on ventilation support, ambulatory status, and steroid therapy was collected.
Main Results:
- Pulmonary function (FVC, FEV1, PEF) significantly decreased with age, with z-scores falling below normal ranges around age 10.
- Pulmonary function was notably lower in non-ambulatory and non-steroid-treated patients.
- Deterioration may occur earlier than indicated by traditional %pv and absolute value measurements.
Conclusions:
- Z-score analysis suggests earlier pulmonary function decline in DMD males than previously recognized.
- Early loss of ambulation, lack of steroids, and delayed steroid initiation are risk factors for poorer pulmonary outcomes.
- Longitudinal cohort studies are recommended to validate these findings.
Introduction:
Respiratory status is one of the main factors affecting the length of survival in patients with Duchenne muscular dystrophy (DMD) - the most common, severe, progressive muscular dystrophy. Aim of the study was (1) to assess pulmonary function in DMD patients using the z-score method and (2) to identify factors affecting it, irrespective of disease progression.
Material And Methods:
We evaluated 55 boys (aged 5-18 years) with DMD. The spirometry was performed with: forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), peak expiratory flow (PEF) analysis as absolute values (in litres or litres/min), % predicted value (%pv) and z-scores (z). Information on the need of ventilation support, ambulatory status and steroid therapy was collected.
Results:
25 (45%) subjects were non-ambulatory, 38 (69%) used steroid therapy. Mean FVC[z] -2.4 ±2.2, FEV1[z] -2.0 ±1.9, PEF[z] -1.5 ±1.3 values significantly decreased with age (r = -0.62/-0.65/-0.55; p < 0.001 respectively), after reaching the peak values in the range 9-12 or 6-9 years of age depending on the analysis method (absolute, %pv or z-score). The results fell below the normal range (z-score < -1.64) at the age of 9.8/10.4/11.6 years and below 80%pv at 10.7/12.2/13.2 for FVC/FEV1/PEF, respectively. The pulmonary function test results were significantly lower in non-ambulant (p < 0.001) and non-steroid patients (p < 0.02).
Conclusions:
Analysis of the pulmonary function test based on z-scores shows that deterioration of pulmonary function in DMD males may occur earlier than we thought when measured by %pv and absolute values. Early loss of ambulation, lack of steroids and delayed steroid therapy are risk factors for worse pulmonary outcomes. To confirm these findings, cohort longitudinal studies are necessary.
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