New study puts number at nearly 1 million in the United States. Research may help with diagnosis and treatment.

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Researchers used an algorithm to sift through 125 million health records. Getty Images

The number of people living with multiple sclerosis (MS) is now estimated at nearly 1 million in the United States, more than twice the long-standing estimate of 400,000.

The research confirmed more women than men have the disease, but now it’s estimated that women outpace men 3 to 1. Earlier estimates suggested a 2-to-1 difference.

The study was conducted by the National Multiple Sclerosis Society and published this month in Neurology, the medical journal of the American Academy of Neurology.

The study also opened the door for new research in other illnesses.

Nick LaRocca, PhD, vice president of healthcare delivery and policy research for the National Multiple Sclerosis Society, says there’s no evidence yet that there’s an actual increase in MS. There’s just now more people who have a diagnosis.

LaRocca discussed several possible reasons for this increase in diagnoses.

“The diagnosis process has become more refined,” LaRocca told Healthline. “People are diagnosed better, sooner, and more readily.”

“There is an increase in prevalence with people living longer, population growth, and more people living in the U.S.,” he added. “Lifestyle changes and diet could also be playing a role.”

The increase could partially be contributed to the large number of treatments today.

“If no treatment is available, there is less reason to establish a diagnosis,” he noted.

This new data helps researchers have a better understanding of MS and provides tools to do more studies to look at environmental triggers.

“How can we cure MS? By preventing it from starting at all is part of the answer,” LaRocca said. “If we can find environmental triggers, then we could reduce risk and maybe prevent it.”

The data also spotlights the need for more and better care.

“MS is a more challenging disorder than we realize, and there is a greater need than we realized,” LaRocca explained. “We need to work hard and redouble our efforts to make sure that everyone diagnosed with MS has access to quality medical care and access to treatments that can help with MS.”

“We have to do a better job at not only making sure they have access to quality care, but they are using the quality care,” he said. “It can make a difference in their lives with MS to take care.”

“And we need to build the MS clinical workforce, which is strained or not available, especially in rural areas,” he added.

The study also highlights the need for a cure.

“We have a mission to find a cure,” Tim Coetzee, PhD, chief advocacy, services, and research officer at the National Multiple Sclerosis Society, told Healthline. “This information will help with advocating for more funds.”

“We’re not finished,” LaRocca said. “We are still working with the data, exploring options, and looking at racial and ethnic differences as well.”

The study involved 125 million health records.

Coetzee calls the study “remarkable” and a tour de force.

Coetzee explains how epidemiologists came together to create an algorithm that collected a lot of data in a statistically valid way.

The algorithm was inspired by the Centers for Disease Control and Prevention (CDC) program to find alternatives to improve data collection.

Researchers in this study used three major groups of records that encompassed private healthcare, government-funded healthcare, and veterans healthcare.

“Without a national health system, or government-funded registry, this is a powerful tool,” he said. “Others can learn from and adapt.”

The research team created an algorithm, applied it to an administrative data set, then looked at clinical data to see if it was verified. They found it possible to identify the formula that identified the highest number of cases with the lowest rate of misidentifying cases.

Researchers aren’t able to segment the data to define types of MS. There’s only one administrative code used for MS that’s not broken up by subtype.

“For example, with Lou Gehrig’s disease (ALS), when a diagnosis is given the patient it automatically coded into Medicare and is immediately picked up by the algorithm. ALS is now using this algorithm for research,” Coetzee explained.

“I’m excited that in this era of big data that we can come up with a way that really builds on bringing all these health records together,” Coetzee said. “We solved a challenging problem for people with MS and set us on a path for even more progress.”

The project cost a little less than $1 million and took more than four years to compile.

Scientists donated their time and effort to take advantage of the data being available at an economical cost.

Editor’s note: Caroline Craven is a patient expert living with MS. Her award-winning blog is, and she can be found on Twitter.