People of certain racial and ethnic groups appear to be at increased risk for developing spondylitis and experiencing more severe symptoms. It’s still unclear what causes spondylitis, though it’s believed to involve a variety of risk factors that include certain genes and details about the environment in which people live.
Links between race, ethnicity, and disease are complex and not yet well understood. It’s important to keep in mind that many biological, social, and cultural factors inform every person’s unique racial and ethinic identity. These factors can also influence health.
Studies have found that white people are more often diagnosed with spondylitis when compared with Black and Hispanic people, though studies find different rates. One U.S.-based study found white people were 10 times more likely to be diagnosed with ankylosing spondylitis (AS) — a severe form of spondylitis — than African Americans.
Another study of Americans with insurance coverage estimated that white people were at twice the risk of being diagnosed with AS compared to Black people. The same study found that white Americans with insurance were five times more likely to be diagnosed with psoriatic arthritis (one type of spondylitis) compared with Black Americans.
There are fewer studies that cover differences in spondylitis among other populations. One study from 2012 examining the frequency of spondyloarthritis in Mexican Americans showed similar frequency as white Americans.
Multiple researchers have raised concern about detection bias with regard to diagnosing spondylitis among people of color. Since it has been believed that white people are at higher risk for AS, health care providers may tend to suspect AS more often when treating white people while missing symptoms of spondylitis in people of color.
Some researchers have noted that reduced access to diagnostic tests and specialists may also affect the numbers of people of color diagnosed with rheumatic diseases. Multiple studies show that Black Americans are less likely to receive appropriate treatment for chronic pain.
Additionally, research has found that Black Americans are less likely to have access to health insurance and primary health care that might make it easier to receive referrals to a rheumatologist for diagnosis.
Researchers suggest these disparities may make it harder to know the true incidence and prevalence rates of spondylitis in the U.S. among people of color.
Traditionally, it has been assumed that diseases that appear linked to race and ethnicity also share a genetic link. However, research increasingly proves that there is no genetic basis for race.
Some researchers use spondylitis as an example of this. A particular variation of a gene known HLA-B27 is linked to AS. Testing for HLA-B27 is sometimes performed as part of the process for diagnosing spondylitis. White people are seven times more likely to have an HLA-B27 allele than Black people, according to past research. Other research has found that “the prevalence of HLA-B27 and AS is higher in whites and certain Native Americans than in African Americans, Asians, and other non-white ethnic groups.”
Some researchers suggest that the focus on this specific gene may lead to Black people not being diagnosed with AS if they do not test positive for HLA-B27.
A study from 2017 found that “Black and, albeit less so, Latino patients have more severe disease than white patients with AS.” Black participants showed more functional impairment and greater elevation in inflammation markers, such as erythrocyte sedimentation rate and C-reactive protein. They also had a lower frequency of HLA-B27. However, the researchers could not determine the reason for these discrepancies.
More research is needed in order to understand how race and ethnicity influence the risk for developing spondylitis and experiencing more severe symptoms.
The question is further complicated by the fact that people of color are underrepresented in clinical trials for inflammatory arthritis and genetic research as a whole. Efforts are underway to better understand why clinical research lacks diversity and to ensure that trial participation will be more inclusive in the future.
Rheumatology is one of the least diverse fields of medicine, with only an estimated 25 percent of people of color among health care providers in the U.S. However, the American College of Rheumatology has announced plans to actively recruit trainee doctors with more diverse backgrounds into rheumatology programs going forward.
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