ACTRIMS 2023: NMOSD affects 3 times more women than men in US

Black women have the highest disease prevalence, health records show

Marisa Wexler, MS avatar

by Marisa Wexler, MS |

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The annual prevalence of neuromyelitis optica spectrum disorder (NMOSD) in the U.S. is considerably higher than previously estimated, affecting about nine out of every 100,000 people, according to a study that analyzed 2021 electronic health records.

The data also showed that the disease is more than twice as common among Black Americans than in white Americans, and around three times more common in women than men.

The findings were shared at the Americas Committee for Treatment and Research in Multiple Sclerosis (ACTRIMS) Forum 2023, held Feb. 23-25 in San Diego and virtually, in the poster “Estimating the Prevalence of Neuromyelitis Optica Spectrum Disorder Using 28.7 Million Electronic Health Records from the United States.”

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‘This rare disease affects all populations’

NMOSD is a rare autoimmune disease, in which the immune system mistakenly attacks nervous system cells, mainly resulting in inflammation of the optic nerve — which sends and receives signals from the eye — and the spinal cord. This leads to vision and movement problems.

“This rare disease affects all populations; unfortunately, the burden of NMOSD in the U.S. has been poorly characterized,” the researchers wrote.

The only estimate of the prevalence of NMOSD in the U.S. comes from a study done in Olmstead County, Minnesota. That study estimated that, in 2011, the autoimmune disease affected about four out of every 100,000 white residents and 13 out of every 100,000 Black residents.

This knowledge gap “impedes efforts to define the needs of persons with NMOSD in the U.S. healthcare systems, determine suitable diversity estimates for clinical trial recruitment, and estimate numbers of individuals who may benefit from the available and novel therapies,” the researchers wrote.

Women are disproportionately affected by NMOSD …, particularly Black women who had the highest prevalence across all ages.

To obtain an updated estimate of NMOSD’s prevalence in the country, including by age, sex, and race, researchers at the Cleveland Clinic Foundation and Case Western Reserve University, in Cleveland, analyzed 2021 data from the TriNetX Research Network. This is a private claims database that collects electronic healthcare records from 55 U.S. healthcare organizations. In 2021, the TriNetX Research Network contained information on nearly 29 million people.

Results showed that NMOSD affected 9.1 out of every 100,000 people in the overall population — a prevalence that was “substantially higher than prior estimates,” the researchers wrote.

The disease’s prevalence varied according to race and sex. The prevalence of NMOSD was about 17 out of every 100,000 Black Americans, more than twice as high as for white Americans, at 7.3 out of every 100,000 people.

Rates of NMOSD were also about 30% higher for Asian Americans compared with their white counterparts, estimated at 10 out of every 100,000 people.

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Highest prevalence of NMOSD found in people 40-44 years old

NMOSD was also about three times more common among women than in men (12.6 vs. 4.6 out of every 100,000 people). Within racial groups, the most pronounced prevalence difference in terms of sex was among Black Americans, with women being four times more affected than men.

Among women, NMOSD’s prevalence was greatest in Black Americans at 24.8 out of every 100,000 people, followed by Asian Americans at 14 of 100,000 people, and white Americans at 9.5 per 100,000. Group differences relative to white Americans were statistically significant.

NMOSD rates were 31% significantly higher for Black men compared with white men (5.9 vs. 4.5 per 100,000 people), though there was no significant difference between white and Asian men (4.9 per 100,000).

In addition, people ages 40-44 years had the highest prevalence of NMOSD, at 22.1 per 100,000 in women and 8.2 per 100,000 in men.

These findings highlight that “women are disproportionately affected by NMOSD …, particularly Black women who had the highest prevalence across all ages,” the researchers wrote.