Contrary to a widely accepted belief, African-Americans may have a higher rather than lower risk of developing multiple sclerosis (MS) than Caucasians, according to a new study in the May 7, 2013, print issue of Neurology.
"Our population-based study is the first of its kind to look at this question. The belief (that African- Americans have a lower risk of developing MS) was based on evidence that was problematic," said study author Annette Langer-Gould, MD, with Kaiser Permanente Southern California Department of Research & Evaluation in Pasadena, Calif., and a member of the American Academy of Neurology.
For the study, researchers examined the entire database of more than 3.5 million members of the Kaiser Permanente Southern California health plan over a three-year period and identified 496 people with newly diagnosed MS. This type of study, which is termed population-based, is considered a more accurate way to determine disease risk than to examine only those people who attend a specific clinic or hospital.
The study found that African-Americans had a 47 percent increased risk of MS compared with Caucasians, while Hispanics and Asians had a 58 and 80 percent lower risk than Caucasians.
Sex differences in MS risk were also highlighted in the study. The higher risk in African-Americans was found in women only whereas the lower risk for Hispanics and Asians was found in both sexes. African-American women had triple the risk of MS compared to African-American men.
African-Americans made up 21 percent of those with MS, while they made up only 10 percent of the total study population. Caucasians made up 52 percent of those with MS, compared to 38 percent of the total population. A total of 23 percent of those with MS were Hispanic, compared to 40 percent of the total population. Asians made up 3 percent of those with MS, compared to 9 percent of the population.
"One explanation for our findings is that people with darker skin tones have lower vitamin D levels and ultimately, an increased risk, but this would not explain why Hispanics and Asians have a lower risk than Caucasians," said Langer-Gould. "About 19,000 people per year, or 250 people per week, will be diagnosed with MS in the US alone. These numbers highlight the need for more minorities to be included in MS studies, so that we can fully understand how race may play a role in developing the disease."