Assessing the growth of children with spinal muscular atrophy using specific curves: A retrospective cohort study

Area of Science:

• Pediatric Endocrinology
• Neuromuscular Disorders
• Growth and Development

Background:

• Children with spinal muscular atrophy (SMA) exhibit atypical growth patterns.
• Standard World Health Organization (WHO) growth charts may not accurately reflect growth in SMA.
• Disease-specific growth curves for SMA were established in 2021.

Purpose of the Study:

• To evaluate the application of SMA-specific growth curves in pediatric patients.
• To compare growth and body composition in SMA children using SMA-specific versus WHO growth standards.
• To assess nutritional status more accurately in children with SMA.

Main Methods:

• Retrospective cohort study of 19 pediatric SMA patients.
• Monthly anthropometric measurements (length, weight) recorded from admission to discharge.
• Calculation of body mass index-for-age z scores (BMIz) and length-for-age z scores (LAzs) using WHO and SMA-specific curves.
• Assessment of triceps skinfold (TSFz) and mid-upper arm circumference z scores (MUACz) using WHO references.

Main Results:

• SMA-specific curves indicated significantly different BMIz at admission compared to WHO curves (0.77 vs. -1.31, P < 0.01).
• Using SMA curves, 42.1% of children were classified as overweight, versus 0% with WHO curves.
• Triceps skinfold z scores correlated better with BMIz derived from SMA curves (R²=0.46) than WHO curves (R²=0.27).
• Longitudinal analysis showed stable BMIz, slight increases in height-for-age z scores, declining MUACz, and increasing TSFz over time.

Conclusions:

• SMA-specific growth curves provide a more accurate assessment of nutritional status and body composition in children with SMA.
• The study cohort demonstrated increased fat accretion and stable BMI over the follow-up period.
• Disease-specific growth charts are crucial for monitoring growth in pediatric SMA.