Multiple Sclerosis patients by the numbers

April 11, 2016 Pavle Repovic, MD, PhD

How many people in the United States have multiple sclerosis? As it turns out, answering this seemingly simple question is quite challenging.

Some time ago, the National MS Society recognized that the commonly used figure of 400,000 may be out of date because it was based on surveys done in the 1990s. The society formed an MS Prevalence Workgroup, and its work was recently published in the journal Neurology.

The results? There are “at least” 400,000 Americans with MS.

Incomplete picture

In epidemiology, prevalence refers to the total number of people with a certain condition at a specific point in time. By examining a nationwide database of commercial health insurance claims for more than 42 million Americans between 2008 and 2012, the authors found that the prevalence of MS in the United States was 149.2 per 100,000 individuals, or 403,630 people nationwide.

As the authors of this study point out, extrapolating the data from commercially-insured patients to the entire population may be fraught with inaccuracies. Their study does not include the uninsured and people with MS who are enrolled in government insurance programs such as Medicare, Medicaid and options for military veterans. To date, there are no estimates of MS prevalence in the government-insured population.

More women than men

The authors strived to count only people with a confirmed MS diagnosis, so their estimate is considered conservative, or “at least.” Nonetheless, the number provides a useful update on a subject of great interest to the MS community.

According to the study, the prevalence of MS did not change between 2008 and 2012. In addition, the female-to-male ratio was 3.13:1, in line with prior reports in the U.S. and elsewhere.

Geographic numbers

The geographic distribution of MS patients in the U.S. was reported across four regions: Northeast, Midwest, South and West. To us, in the Pacific Northwest, it came as somewhat of a surprise that the prevalence was lowest in the West, at 110.7 per 100,000, and highest in the Northeast, at 192.1 per 100,000.

The prevalence of MS typically has been high in the Pacific Northwest. But for this study, our region was part of an area that included all states west of the Texas-North Dakota line, including Hawaii and Alaska.

Between 2008 and 2012, the West was the only region where the prevalence of MS decreased, according to the study. This may be related to the change in the number of people included; as in 2010 and 2011, a disproportionately large number of people in the West left the commercial insurance database. More in line with expectations was the finding that the prevalence of MS was lower in the South than in the Northeast or Midwest.

If you have questions about MS or need help with treatment, call the MS Center at Swedish at 206-320-2200, or visit our website.

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