Multiple sclerosis patients whose blood tests reveal elevated neurofilament light chain, a biomarker of nerve damage, could see worsening disability one to two years later, according to new findings. 
 
Almost 1 million Americans suffer from MS. In advanced cases, patients may have limited mobility and experience spasticity, weakness, poor coordination, and incontinence. However, recent advances suggest that more severe symptoms can be substantially delayed or even averted. 

In the study, researchers at the University of California, San Francisco, and the University Hospital and University of Basel, in Switzerland, looked at the incidence of disability worsening, defined as six months or more of increased impairment reflected in a higher score on the Expanded Disability Status Scale. They distinguished between disability worsening with relapse – which involves residual symptoms or the return of old ones following relapse – and gradual progression of symptoms without relapse.  

The researchers tracked data spanning a 10-year period from about 4,000 patient visits to UCSF, and from approximately 9,000 patient visits to multiple sites in Switzerland. Together, the two groups included almost 1,900 patients. Among those, 570 patients were identified with disability that continued to worsen, of which the majority were independent of relapses. 
 
Elevated NfL levels were linked to up to a 91 percent higher risk of worsening disability with relapse approximately a year later, and up to a 49 percent higher risk of worsening disability without relapse nearly two years later, the researchers found.

Future investigation will investigate therapies that can stop progression during this period of elevated NfL.

The study was published in the journal JAMA Neurology.