Nearly 1 million Americans have MS, not 400,000 as previously thought – NMSS Study

A new National MS Society (NMSS) prevalence study estimates that nearly 1 million people have multiple sclerosis in the USA. And that’s more than twice as many as previously thought.

The new estimate is that 947,000 people have MS, compared with the long-accepted figure of 400,000.

Study results were published as “The Prevalence of Multiple Sclerosis in the United States: A Population-Based Healthcare Database Approach”. The poster was unveiled at the recent Joint ECTRIMS-ACTRIMS Meeting in Paris.

The findings are currently tentative, pending completion of a peer review and the prevalence study’s publication in a scientific journal. This could happen as early as next year.

prevalence study

Dr Nicholas LaRocca.

NMSS vice president of healthcare delivery and policy research, Dr Nicholas G LaRocca. has headed the MS Prevalence Initiative since its launch in 2014.

Speaking with Multiple Sclerosis News Today (MSNT), LaRocca said the findings were “definitely not what we expected.”

He told MSNT that the dramatic jump seen in the prevalence study has more to do with methodology than an actual rise in the number of MS cases — though he doesn’t discount that possibility.

“In the past, prevalence was looked at as the number of people diagnosed with a given disorder at a particular point in time. But people with a given condition don’t necessarily have the sort of contact with the healthcare system that would appear to generate a valid diagnostic report.

Prevalence study needs to look at several years

“In order to get an accurate estimate, you can’t look at one point in time or even a year or two, but several years. That really opened up the possibility that the numbers would be much greater than we anticipated,” LaRocca said.

The new NMSS prevalence study involved a working group of up to 20 epidemiologists, statisticians and neurologists meeting virtually every week. It cost $1 million.

It drew on data culled from five national databases. These were Optum, Truven Health Market Scan, Department of Veterans Affairs, Medicare and Medicaid. There was also one regional database, Kaiser Permanente of Southern California.

Together, these databases provided information on more than 100 million people — a third of the US population. Researchers reasoned that nearly all persons with MS, except the uninsured, would be captured in one of these programmes.

However, it does exclude children, Native Americans, undocumented residents, and prisoners. It also misses people who seek treatment at alternative medical clinics rather than through the healthcare insurance system.

The study showed an overall MS prevalence of a staggering 402.8 cases per 100,000 inhabitants. This is a significant increase from 58 per 100,000 in 1976, and 85 per 100,000 for the years 1989-94.

“When you’re talking about the unmet needs of a given population, if you don’t know how large that population is, it’s hard to effectively advocate for them,” La Rocca said. “It’s also important from a scientific perspective.”

Interviewed by MSNT, LaRocca pointed out that four decades have gone by since the last “really solid study” of MS prevalence in the US.

“The last time there was a really solid study of MS prevalence in the United States was 1976. Over time, that estimate was updated, adjusted and corrected, so that after a while it started to fray,” he said.

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* * * * * is the personal website of Ian Franks, a freelance medical writer and editor for various health information sites. He enjoyed a successful career as a journalist, from reporter to editor in the print media. He gained a Journalist of the Year award in his native UK. Ian received a diagnosis of MS in 2002 and now lives in the south of Spain. He uses a wheelchair and advocates on mobility and accessibility issues.


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