By Sandra Basu
BALTIMORE — Why are incident rates for multiple sclerosis (MS) increasing in African-Americans compared with other racial backgrounds, and why is the disease, on average, more severe in that population?
Those are among the questions plaguing VA and military researchers as they try to respond to the trends and provide appropriate care to patients.
Christopher Bever, MD, who serves as director of VA’s MS Center of Excellence (MSCoE) East, told U.S. Medicine that MS in African-Americans has been “shifting” and it is an area of “active study” both by VA and by others.
“African-American patients oftentimes have more impairment and more disability, and so we are working in our programs to make sure we can deal with the more severe consequences of MS,” Bever noted. “Many of those problems turn out to be like the problems seen in the spinal injury population because MS does affect the spinal cord.”
MS and Race
Two recently published studies on MS demographics in certain segments of the military population raise issues about race and disease incidence.
One of the studies, published in 2012 by VA researchers, examined Gulf War medical records and data from the DoD and VA for cases of MS in servicemembers who served in the Gulf War era between 1990 and 2007 and who were service-connected for the disorder by VA from 1990 on.
For the study, active duty population data were obtained for each year 1990-2000 and 2001-10 from the Defense Medical Epidemiological Database. In the study, a total of 2,691 patients were confirmed as having MS.
What the researchers called “novel,” was their findings that the black veterans had a higher incidence rate of MS (12.1 per 100,000 persons) than white veterans (9.3 per 100,000 persons).
“Potential explanations for the high multiple sclerosis incidence rates for blacks are important to explore,” the researchers wrote, noting that, historically, MS rates have been higher in whites. Based on their prior work with military cohorts, the researchers wrote that “these changes have manifested themselves fairly recently, over the past two to three generations.”
Environmental risk factors as well as genetic susceptibility were among the factors that the authors said should be explored to better understand their observations.
Another 2012 study, published in Military Medicine, examined estimated incidence of MS among military personnel from 2000 to 2009, also finding that black non-Hispanics had a higher incidence rate than white non-Hispanics, at 18.3 per 100,000 person-years vs. 12.5 per 100,000 person-years, respectively. That study also indicated that black females had higher rates than their white counterparts.
“[Incidence rates] of MS diagnoses among blacks, and specifically black females, were higher than their white counterparts. This relationship in an adult population has not been previously seen in literature and has only recently been described in children. The novelty of this finding is perplexing,” the study stated. “Do these results represent an unidentified risk factor in our population among black females, or are these results representative of actual risk not previously appreciated in the general U.S. population?”
Whatever the reasons for higher incidence rates in blacks compared with whites, research has shown that the disease tends to be more aggressive in African-Americans.
One study published in 2004 examined medical records of 375 African-American (AA) patients with MS compared with 427 Caucasian-Americans (CA) with the disease and found that the median time to ambulation with a cane was six years shorter in AA than in CA subjects (16 vs. 22 years). The median time to wheelchair dependency was eight years shorter in the AA than in CA group (30 vs. 38 years). 3
Researchers attributed the progression of disability in African-Americans to the older age of onset in the study group and to the greater likelihood of transverse myelitis in the African American group, which they said was a predictor of ambulatory disability. Transverse myelitis is a neurological disorder caused by inflammation across both sides of one level, or segment, of the spinal cord.
“It is important to recognize that the clinical manifestations of MS in AA patients differ somewhat from those in CAs and that these differences are likely to be biologically based. AA patients with MS are at high risk for disability; thus, early initiation of treatment seems prudent,” the researchers noted.
A brochure from the National Multiple Sclerosis Society addresses some of the issues surrounding African-Americans and MS, noting, “The myth that African-Americans do not get MS is just that — a myth. African-Americans do get MS. In fact, studies suggest that MS can be especially active in African-Americans.”
The brochure points out that African-Americans are more likely to experience more relapses and greater disability, have an increased risk of progressing to require ambulatory assistance earlier and are more likely to develop involvement of the optic nerves and spinal cord (optico-spinal MS) and inflammation of the spinal cord (transverse myelitis).
1. Wallin MT, Culpepper WJ, Coffman P, Pulaski S, Maloni H, Mahan CM, Haselkorn JK, Kurtzke JF; Veterans Affairs Multiple Sclerosis Centres of Excellence Epidemiology Group. The Gulf War era multiple sclerosis cohort: age and incidence rates by race, sex and service. Brain. 2012 Jun;135(Pt 6):1778-85. doi: 10.1093/brain/aws099. PubMed PMID: 22628389.
2. Deussing EC, Jankosky CJ, Clark LL, Otto JL. Estimated incidence of multiple sclerosis among United States Armed Forces personnel using the Defense Medical Surveillance System. Mil Med. 2012 May;177(5):594-600. PubMed PMID: 22645888.
3. Cree BA, Khan O, Bourdette D, Goodin DS, Cohen JA, Marrie RA, Glidden D, Weinstock-Guttman B, Reich D, Patterson N, Haines JL, Pericak-Vance M, DeLoa C,Oksenberg JR, Hauser SL. Clinical characteristics of African Americans vs Caucasian Americans with multiple sclerosis. Neurology. 2004 Dec 14;63(11):2039-45. PubMed PMID: 15596747.