People with rapid weight loss in the earlier stages of amyotophic lateral sclerosis (ALS) — before invasive ventilation is needed to support breathing — are more likely to have a poorer prognosis in its later stages than those who don’t, a study reports.
The study, “Body weight variation predicts disease progression after invasive ventilation in amyotrophic lateral sclerosis,” were published in Scientific Reports.
As ALS progresses and patients lose motor neurons, nerve cells of the spinal cord and brain responsible for voluntary muscle control, respiratory muscles like those of the diaphragm will be affected. To avoid respiratory failure, patients require a tracheostomy and invasive ventilation (TIV) to be able to breathe. (A tracheostomy is a surgical procedure to create an opening in the windpipe for mechanical ventilation.)
Many factors are known to influence outcomes in ALS, including age at disease onset, the body region most affected at onset, delays in the diagnosis, functional test scores, and those impacting nutrition and psychological well-being.
“With regard to the nutritional aspect, low body mass index (BMI) at diagnosis, rapid body weight decline, and hypermetabolism [increased metabolic activity] in the early stages [of ALS] typically indicate a short survival time or an earlier need for tracheostomy,” the investigators wrote.
“However, the effects of weight variations on the functional prognosis after tracheostomy and invasive ventilation in ALS remain unknown,” they added.
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Scientists at the Tokyo Metropolitan Institute of Medical Science explored the possible relationship between early weight loss and disease progression in its more advanced stages.
Their study enrolled 60 ALS patients, all on ventilation and three with familial disease, who were divided into two groups based on the speed at which they lost weight during earlier disease stages, measured as the time from diagnosis to the start of invasive ventilation. Weight loss speed was calculated based on the rate of a person’s decline in body mass index (ΔBMI) over that time frame.
Statistical analyses examined the relationship between ΔBMI and changes in patients’ motor skills and ability to communicate.
Results showed that those who lost weight faster in the years after diagnosis (ΔBMI greater than 1.7 kg/m2 per year, about 3.7 lbs/m2) lost an ability to communicate and open their mouths sooner than those who dropped weight at a slower rate (ΔBMI lower than 1.7 kg/m2 per year).
Statistical analyses found a greater ΔBMI to be an independent prognostic factor for the early development of both total quadriplegia and ophthalmoplegia.
“Our findings may provide not only insight on the pathophysiology [disease mechanisms] of ALS but also provide further information for patients and clinicians particularly at the time of decision-making for TIV use,” the researchers wrote.
“A considerable number of patients are afraid to lose their ability to communicate after TIV use. Our findings may bring hope to patients who showed relatively slow progression and slow BMI decline before TIV use,” they added.