Body mass index in type 2 spinal muscular atrophy: a longitudinal study

Area of Science:

• Pediatric Endocrinology
• Neuromuscular Disorders
• Clinical Nutrition

Background:

• Type 2 spinal muscular atrophy (SMA) patients frequently exhibit low body mass index (BMI), with many requiring tube feeding.
• Feeding difficulties are common in SMA, particularly in type 1, but also impact type 2 patients.

Purpose of the Study:

• To review body mass index (BMI) in Italian pediatric type 2 SMA patients (0-20 years).
• To identify differences in BMI based on ventilation, motor function, and gene copies.
• To analyze BMI/age z-score trends and influencing factors in this cohort.

Main Methods:

• Retrospective study of 102 Italian pediatric type 2 SMA patients with 344 cross-sectional visits.
• Age-adjusted BMI calculated using CDC's BMI-for-age tool and compared to standard growth charts.
• Multivariate analysis performed on 58 patients with longitudinal data.

Main Results:

• BMI/age z-scores varied, with 28% below -2SD and 9% above +2SD.
• BMI/age z-scores showed stability before age 5, with increasing numbers below -2SD after age 5.
• Baseline BMI/age z-score and gender significantly predicted changes in BMI/age z-scores over time.

Conclusions:

• Continuous monitoring of weight and BMI/age z-scores is essential for type 2 SMA patients.
• Further research into chewing, swallowing, and body composition is needed to understand weight issues.
• Gender and initial BMI/age z-score are key factors in BMI changes in pediatric type 2 SMA.