Multiple Sclerosis Is More Common in Black Women than in White Women

Study from Kaiser Permanente contradicts the widely accepted assertion that blacks have a lower risk of multiple sclerosis than whites.

The authors of “Incidence of Multiple Sclerosis in Multiple Racial and Ethnic Groups,” published in Neurology, examined the electronic health records of more than 3.5 million patients and identified 496 people newly diagnosed with multiple sclerosis (MS) who met the McDonald diagnostic criteria and calculated the incidence of MS and risk ratios comparing incidence rates between racial/ethnic groups.

For the study, the average age at diagnosis was 41.6 years (with a range of first age of diagnosis of 8.6-78.3 years), and 70.2% of patients were women.

The researchers reported that 79.3% of black patients diagnosed with multiple sclerosis were women, a significantly higher percentage than their white (67.8%), Hispanic (68.1%), and Asian (69.2%) counterparts. Analysis of data also revealed the incidence of MS was higher in black patients and lower in Hispanics and Asians than whites. Black women had a higher risk of MS than white women, whereas black men had a similar risk of MS compared with whites.

According to the authors, these findings “do not support the widely accepted assertion that blacks have a lower risk of MS than whites.”

A news release that accompanied publication of the study results noted that “the belief that MS is rare in blacks is based on worldwide prevalence studies and a single study of Korean War veterans in the 1950s, which found white men were twice as likely to receive disability compensation for MS as black men.

Annette Langer-Gould

Lead study author , MD, PhD, of the Kaiser Permanente Southern California Department of Research & Evaluation, said, “A possible explanation for our findings is that people with darker skin tones have lower vitamin D levels and therefore an increased risk of MS. However, this does not explain why Hispanics and Asians have a lower risk of MS than whites, or why only black women but not black men are at a higher risk of MS.”

These findings indicate that “including persons from different racial and ethnic groups in future studies of MS susceptibility and prognosis will likely reveal important insights into the causes of this often debilitating disease,” said Langer-Gould.

She said that MS risk is determined by “complex interactions between race, ethnicity, sex, environmental factors and genotypes,” and that although additional research is needed, “possible explanations for the higher incidence of MS in black women include a greater prevalence of hormonal, genetic, or environmental risk factors such as smoking, compared to patients from other racial or ethnic groups.”