Treatment may help maintain nutrition, prevent stunted growth in SMA kids
Use of DMTs shown to help type 1, 2 children sustain healthy weight: Study
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Disease-modifying therapies can help children with SMA types 1 and 2 maintain a healthy weight and prevent stunted growth, a study suggests.
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Treated SMA type 1 children show improved nutrition and delayed need for feeding tubes compared with untreated peers, the data showed.
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These findings emphasize the need for ongoing specialist dietetic care for children with SMA as prognoses continue to improve with DMTs.
The use of disease-modifying therapies (DMTs) — all widely approved in the last 10 years — may help children with spinal muscular atrophy (SMA) maintain nutrition and prevent stunted growth, an Australian study suggests.
Children with SMA type 1 and type 2 who received approved DMTs maintained a median weight similar to that of healthy youngsters of the same age, the data showed. In contrast, untreated children with SMA type 1 tended to experience a decline in weight relative to their healthy peers, the researchers noted.
“Nutrition outcomes were improved in treated children with SMA 1 and stable in treated children with SMA 2,” the scientists wrote, noting, however, that “prospective studies are required” as more and more children are given such treatment and prognoses continue to improve.
Nonetheless, the team added, “regular dietetic assessment and intervention remain integral to SMA care.”
The study, “A Retrospective Cohort Study of Nutrition Outcomes in Children With Spinal Muscular Atrophy Type 1 and 2 Treated With Disease Modifying Therapies,” was published in the journal Muscle & Nerve.
SMA is a genetic condition that causes progressive muscle weakness and wasting. There are several types, based on when and how symptoms manifest in the absence of treatment.
Children with SMA type 1, a severe form, typically begin experiencing symptoms in their first 6 months of life. Without treatment, these infants typically die within two years. In SMA type 2, signs of the disease become apparent between the ages of 6 and 18 months.
Regardless of the type, SMA can cause problems with nutrition beginning early on, primarily due to swallowing issues. Gastrointestinal symptoms and difficulty eating can limit growth, particularly in a child’s younger years. These challenges, alongside changes in energy use related to SMA, can also contribute to excess weight gain for some children.
Researchers looked at nutrition effects with 3 DMTs for SMA
DMTs are treatments that target the underlying causes of the disorder, potentially slowing or halting progression. Three DMTs had been approved for SMA at the time of this study in both the U.S. and Australia: Evrysdi (risdiplam), Spinraza (nusinersen), and the gene therapy Zolgensma (onasemnogene abeparvovec-xioi).
“All of these therapies have been shown to improve survival, motor function, and attainment of motor milestones in children with SMA,” the researchers wrote.
Now, the team stated, “with DMTs improving prognosis for children with SMA, it is critical to understand the impact of DMTs on nutrition outcomes to ensure nutritional interventions can be appropriately tailored to optimize supportive care.”
To that end, the researchers retrospectively analyzed medical records from children treated at the Royal Children’s Hospital in Melbourne who were diagnosed with SMA type 1 or 2 between 2004 and 2023. Their goal was to investigate nutrition-related outcomes in patients receiving DMTs.
The SMA type 1 group covered 36 infants: 17 who received DMTs and 19 who did not. The untreated infants were all diagnosed before 2019, when available DMT options in Australia remained limited.
Infants who received one or more DMTs were followed for a median of 62.2 months, or slightly longer than five years. The untreated infants, meanwhile, had a median follow-up duration of 6.5 months, which reflected their shortened lifespan without DMTs.
Between birth and 6 months, treated SMA type 1 babies saw a slight median decline in weight relative to the average for healthy infants of their specific age and sex. In comparison, the untreated infants’ median weight declined substantially over this period and remained substantially lower than that of their healthy peers.
“Faltering growth is a common feature of the natural history of SMA [type] 1 but appears to be mitigated by initiation of DMTs,” the researchers wrote.
Many SMA type 1 participants required feeding tubes to supplement nutrition or provide a main source of food. However, DMT-treated participants started tube feeding a median of nearly 10 months later than untreated participants.
“Untreated children with SMA [type] 1 appear to require intensive dietetic input over the course of a shorter life expectancy, where treated children require regular dietetic input over a longer life expectancy,” the team wrote.
With DMTs improving prognosis for children with SMA, it is critical to understand the impact of DMTs on nutrition outcomes to ensure nutritional interventions can be appropriately tailored to optimize supportive care.
The SMA type 2 group included 17 children, all of whom received a DMT. These youngsters had weight and nutrition measurements from when they started a DMT and for up to four years after.
“Nutrition outcomes for children with SMA [type] 2 remained stable during the first 4 years of DMT,” the researchers wrote. Although their weight relative to healthy peers varied, with some children over- or underweight, this stayed approximately consistent over time, the team noted.
Many SMA type 2 participants received nutritional advice or supplements, but none progressed to the point of requiring a feeding tube over four years, the data showed.
As SMA prognosis improves, so too must ‘dietetic care,’ per researchers
According to the researchers, these results may have significance for the management of SMA throughout a person’s life.
“As the clinical [profile] of SMA evolves and prognosis improves, more children with SMA will require long-term specialist dietetic care adapted to the emerging longer-term nutritional implications of DMTs,” the team wrote, adding that “dietetic care remains essential to optimize nutrition outcomes for this cohort.”
According to the team, “resourcing for adequate and sustainable dietetic services should be prioritized in the planning of multidisciplinary … services” for children with SMA.
Nonetheless, the researchers noted that their findings “should be interpreted cautiously due to key limitations,” specifically the study’s retrospective nature and the lack of an untreated group of children with SMA type 2 for comparison.
Studies following up patients over time and “investigating nutrition as a primary outcome of DMTs are required to substantiate these findings and inform the development of targeted SMA nutrition interventions,” the researchers concluded.
