An estimated 947,000 people in the U.S. have multiple sclerosis (MS) — more than double the long-accepted figure of 400,000 — according to a newly completed study organized and funded by the National Multiple Sclerosis Society (NMSS).
“This is definitely not what we expected,” Nicholas G. LaRocca, vice president of healthcare delivery and policy research at the New York-based NMSS, said in an interview with Multiple Sclerosis News Today.
The nonprofit organization presented its poster, “The Prevalence of Multiple Sclerosis in the United States: A Population-Based Healthcare Database Approach,” at the 7th Joint ECTRIMS-ACTRIMS Meeting in Paris, the world’s largest MS research gathering.
Now under peer review, these findings are considered tentative until that review is complete and the study is published in a scientific journal, possibly next year.
LaRocca, who’s headed the MS Prevalence Initiative since its 2014 launch, said the dramatic jump seen in prevalence 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,” LaRocca said. “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. 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.”
June Halper, CEO of the Consortium of Multiple Sclerosis Centers in Hackensack, N.J., was not surprised by the new data.
“Here in New Jersey alone, we have tens of thousands of cases,” she said. “MS now seems to be occurring all over the world, in areas you wouldn’t expect it to occur.”
Kathy Costello, a registered nurse and associate vice president for clinical care at NMSS, also welcomed the new estimate.
“Over the years, lots of numbers have been thrown around. I myself, in my own practice, thought it had to be much greater than 400,000,” Costello said in a video interview at ECTRIMS 2017. “But we’ve been using that number for 25 years because it’s very difficult to get that those kinds of statistics. This has a whole lot of meaning, for treatments, for health economics and for everyone to know what the number really is.”
The latest NMSS study cost $1 million and involved a working group of 15 to 20 epidemiologists, statisticians and neurologists meeting virtually every week.
It drew on data culled from five national databases — Optum, Truven Health Market Scan, Department of Veterans Affairs, Medicare and Medicaid — and one regional database, Kaiser Permanente of Southern California. Collectively, these six databases provided information on more than 100 million people — or well over a third of the U.S. population — with the rationale that “nearly all persons with MS, except the uninsured, would be captured in one of these programs.”
Decades without ‘solid’ update
Among its limitations, the NMSS study excludes children, Native Americans, undocumented residents and prisoners, as well as people who seek treatment at alternative medical clinics rather than the healthcare insurance system.
The study showed an overall MS prevalence of 402.8 cases per 100,000 inhabitants — up from 58 per 100,000 in 1976 and 85 per 100,000 for the period 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.”
Yet, four decades have gone by since the last “really solid study” of MS prevalence in the United States, according to LaRocca, a Maine-based psychologist who has worked in the MS field for more than 38 years.
“The last time there was a really solid study of MS prevalence in the United States was 1976,” he said. “Over time, that estimate was updated, adjusted and corrected, so that after a while it started to fray.”
Efforts to collect fresh data stalled as the NMSS tried to persuade Congress to fund a new study through the Centers for Disease Control and Prevention (CDC) tracking all neurological disorders, not only MS. A few years ago it finally approved such a bill, but the necessary funds never came through and NMSS got tired of waiting, LaRocca said.
“We weren’t sure if Congress would ever act, so we decided we’d do our own study,” he said. “We used administrative datasets that track whenever people have an encounter with a healthcare center. We developed an algorithm to determine which people in those datasets were diagnosed, and then we validated that algorithm.”
Those algorithms for identifying MS patients came from the Department of Veterans Affairs, Kaiser Permanente Southern California and the Canadian province of Manitoba. The NMSS also relied on help from Atlanta-based McKing Consulting, which specializes in healthcare and management.
Women lead in cases
Significantly, women (586.4 per 100,000) are nearly three times as likely as men (207.9) to develop the disease. Broken down by age, people in their 40s, 50s and 60s were most likely to develop MS, with the single highest prevalence — 870.5 per 100,000 — found among women in the 55-64 age bracket.
Regionally, the study found MS much more prevalent in the Northeast (459.3) than in the South (334.7), with the Midwest (434.9) and the West (352.3) somewhere in between.
That comes as no surprise, since MS experts have long theorized that the farther one lives from the equator, the less exposure people have to sunlight — resulting in a much higher prevalence of MS in Canada and northern Europe, particularly Scandinavian countries.
The 2013 MS Atlas, published by the London-based MS International Federation, ranked Canada first worldwide in MS prevalence, with 291 cases per 100,000, followed by Denmark (227), Sweden (189), Hungary (176), Cyprus (175) and Great Britain (164).
LaRocca said lower vitamin D levels appear to increase the risk of developing MS later in life, though Northern Europeans and Africans are genetically different as well.
“There seems to be some critical periods for environmental triggers if you’re born in an area with a high incidence of MS, and then you move to an area with a low incidence when you’re very young,” he said. “You then acquire the risk of that low-incidence area.”
Interestingly, the NMSS study doesn’t look at incidence — the number of new cases that appear in any given year — but rather prevalence. Nor does it break down prevalence according to type of MS.
“Our methodology could not really tell us if MS was itself increasing — and even if we had done that, it’s hard to separate whether a condition is actually increasing, or if it’s just being diagnosed more often,” he said. Nevertheless, he pointed out that “studies in neighboring Canada have reported steep increases in the prevalence of MS over time.”
Impact of therapies
LaRocca, formerly an associate professor at Albert Einstein College of Medicine and New York Medical College, joined the NMSS in 1997. He noted that after the National Institutes of Health finally released its 1976 study in 1981, controversy ensued about its methodology. So in 1992, an adjustment was made which came up with a higher figure.
“No new data collection was done after that, only periodically based on census data,” he said. “Since then, there have been other, scattered attempts to generate estimates, but none of them were really worth anything.”
Another factor, he said, is that until 1993, the U.S. Food and Drug Administration (FDA) had not approved a single treatment for MS. Today, a variety of therapies are available, ranging from Gilenya (fingolimod) — a drug developed by Novartis which in 2010 became the first FDA-approved oral therapy for relapsing MS — to Biogen’s Tecfidera (dimethyl fumarate), approved in March 2013, to treat relapsing-remitting MS.
“We know that when there is no adequate treatment for a condition, either it’s not diagnosed or it doesn’t really appear in the healthcare system,” LaRocca said. “Once there are treatments — and they work — there’s a very strong impetus to diagnose someone with that condition.”