This past week, a new study was published in the journal Neurology that significantly updated previous data on the prevalence of MS in the United States. The prevalence of MS, or the number of people with an MS diagnosis at any one time, was originally thought to be between 300,000-400,000 individuals. This number came from a previous study on prevalence that was published in 1975, as well other relevant updates published since. However, no scientifically sound study this large on the prevalence of MS in the US has been completed since the 1975 report. The results from the study published last week indicated that not only was MS prevalence higher than previously estimated, it was more than double what was expected. The researchers estimated that in the year 2017, over 900,000 individuals in the US were living with MS.1,2
What were the main outcomes?
As mentioned, previous MS prevalence estimates were greatly surpassed, with nearly one million Americans thought to be living with MS (compared to the 500,000 expected). More specifically, the researchers used administrative healthcare data from 2008 to 2010 to determine the MS prevalence for 2010, which was estimated to be 309 cases per every 100,000 Americans (for a total of over 725,000 individuals). The researchers then took these results and utilized them to predict what the prevalence would be for 2017. Their 2017 prevalence prediction was 363 cases per every 100,000 individuals (for a total of over 900,000 individuals). Additionally, women were found to be more commonly affected by MS than men, and the 55-64-year-old age group had the highest prevalence of all age ranges. One other interesting finding was that there seemed to be a geographic gradient of MS prevalence, with a higher prevalence of MS in more northern areas of America than in southern areas.1
Why do these results matter?
The National MS Society sponsored the project and the group of researchers (called the MS Prevalence Working Group). The idea was to better understand the true prevalence of the condition, to help better understand the needs of individuals with MS and their families, as well as to help determine the overall burden of the condition.3 The researchers also felt that in learning more about the prevalence and any trends in areas or individuals with MS, new risk factors or triggers may be identified and/or explored. Overall, the previous estimates of MS prevalence seem to greatly undershoot the actual value (according to these new findings), and thus, imply that there are many more individuals in need of support than originally thought.
How was the study designed?
The study was designed in order to get a reliable measurement of the number of MS cases in the US in a way that was feasible to complete by the researchers. Ultimately, a team of statisticians, healthcare experts, and more were gathered to create an algorithm for identifying MS cases in administrative healthcare data. This administrative healthcare data was first collected between 2008 and 2010 and came from claims information belonging to entities like the Veteran’s Health Administration, Medicare, Medicaid, and several private insurers. The algorithm, or plan, the researchers used to identify cases of MS was to comb through these datasets and identify specific MS-related claims and claims that included evidence of DMT use (disease-modifying therapies). The researchers also adjusted their plan to account for individuals who may not have seen their doctor during 2008-2010, as well as individuals who were uninsured and may not be represented in any claims data.4
Overall, these results suggest that MS is potentially a much larger issue than originally thought, and may set off a trend in future, more-specific MS prevalence research to uncover more about life with MS and its causes.
Wallin MT, Culpepper WJ, Campbell JD, et al. The prevalence of MS in the United States. Neurology. 15 Feb 2019. Available from: http://n.neurology.org/content/early/2019/02/15/WNL.0000000000007035. Accessed February 18, 2019.
Landmark Study Estimates Nearly 1 Million in the U.S. Have Multiple Sclerosis. National Multiple Sclerosis Society. https://www.nationalmssociety.org/About-the-Society/News/Landmark-Study-Estimates-Nearly%C2%A01-Million-in-the-U. Published February 15, 2019. Accessed February 18, 2019.
Nelson LM, Wallin MT, Marrie RA, et al. A new way to estimate neurologic disease prevalence in the United States. Neurology. 15 Feb 2019. Available from: http://n.neurology.org/content/early/2019/02/15/WNL.0000000000007044. Accessed February 18, 2019.
Culpepper WJ, Marrie RA, Langer-Gould A, et al. Validation of an algorithm for identifying MS cases in administrative health claims datasets. Neurology. 15 Feb 2019. Available from: http://n.neurology.org/content/early/2019/02/15/WNL.0000000000007043. Accessed February 18, 2019.