Racial and Ethnic Disparities in Chronic Pain, Including Migraine: More Than Black versus White

A new study examines pain prevalence in Black, White, Hispanic, Asian, multiracial and Native American adults in the United States. The work finds that differences between Black and White groups pale in comparison to differences between other racial/ethnic groups.

Researchers have spent decades investigating racial and ethnic disparities in the experience of chronic pain. Most of that work, however, focuses on differences between Black and White groups, leaving the experience of other groups unexplored. A new study now fills that gap, with some surprising results.

Researchers led by Anna Zajacova at the University of Western Ontario in Canada use data from the U.S. National Health Interview Survey to examine the prevalence of pain in a number of previously overlooked racial/ethnic groups. They found the lowest pain prevalence in Asian Americans, and the highest in multiracial adults and Native Americans, with the prevalence of pain in Black, White, and Hispanic adults falling in between those groups.

Notably, the differences in pain prevalence between Asian Americans and multiracial adults and Native Americans were much greater than those between White and Black adults; the last two groups actually differed relatively little, contrary to prevailing assumptions.

The investigators also found that the results held up regardless of how pain was defined, and regardless of where in the body survey participants reported pain (including severe headaches/migraine). Finally, the research showed that socioeconomic status could sometimes, but not always, explain differences in pain prevalence between the different groups.

“I think this is an incredibly important paper,” said Samantha Meints, a clinical pain psychologist at Brigham and Women’s Hospital in Boston, US. Meints, who studies the bio-behavioral mechanisms driving racial and ethnic disparities in pain but was not involved with the current study, was particularly impressed with the researchers’ consideration of multiracial adults and their analysis of potential underlying factors explaining the racial/ethnic differences.

“The fact that these authors were able to look across all of these racial and ethnic categories while still controlling for all of the sociodemographic variables that we often think are driving some of these disparities is incredibly helpful,” Meints told Migraine Science Collaborative.

The authors “clearly acknowledged the complexity between race or ethnicity, pain prevalence, and demographic sociocultural factors and have made an important contribution to the study of disparities in pain. We believe this study will stimulate additional research that will enhance our understanding of the complex relationships between race, ethnicity, and the pain experience,” wrote Fiona Stanaway, University of Sydney School of Public Health, Australia, and Claudia Campbell, Johns Hopkins University School of Medicine, US, in an accompanying editorial.

The new study and editorial appeared in the September 2022 issue of the journal PAIN.

Filling a huge gap
Zajacova, a demographer and sociologist, told Migraine Science Collaborative that she and her co-authors, including Hanna Grol-Prokopczyk from the University at Buffalo and Roger Fillingim from the University of Florida, US, did the study because of a dearth of basic demographic analysis covering a truly representative swath of the US population.

“There are lots of studies on racial and ethnic differences in pain, but either that work is somewhat outdated or included only White and Black adults. And most of the studies are on experimental pain, which is a very different beast than pain prevalence in the community,” she said.

To remedy those deficiencies, the team turned to data from the National Health Interview Survey (NHIS). This continually running, government interview survey of US households has tracked the health of the country since 1957, asking adults 18 years or older living in the community about many different aspects of health.

With regard to pain, NHIS asks about the anatomical sites where respondents may experience pain, the frequency and severity of pain, and pain interference with daily living activities. NHIS, and thus the current study, included people who reported severe headache/migraine, as well as joint pain, jaw/ear pain, low back pain, and neck pain.

Zajacova and colleagues’ research included data starting from 2010, when NHIS first began asking global questions about pain, through to 2018, which was the most recent year of data available to the researchers as they were writing their study. A total of 273,972 survey respondents were included in the study.

The research looked at six pain measures as dependent variables, including severe pain, high-impact chronic pain, widespread pain, persistent pain over three months, persistent pain over six months, and any pain (pain in at least one anatomical site). The investigators also examined the role of socioeconomic status (SES) as a potential mediator of racial/ethnic differences in pain prevalence.

Where are the greatest differences?
When considering all the racial/ethnic groups together, the investigators saw that severe pain had the lowest prevalence (6.4%), while any pain had the highest (51%).

They also discovered that Asian Americans had the lowest pain prevalence, by far, for all six pain measures, while Native Americans and multiracial adults had the highest prevalence for all of the measures. For instance, the prevalence of severe pain was 2.4% in Asian Americans, but 8.7% in multiracial adults, and 11.1% in Native Americans. The differences between Asian Americans and those last two groups were much higher than the differences between White (6.8%) and Black (7.6%) groups. Hispanic adults had a severe pain prevalence of 5%.

The authors stressed in their paper that these findings equate to Hispanic adults having twice the prevalence of severe pain as Asian Americans do, while multiracial adults have 3.6 times the prevalence, and Native Americans 4.6 times the prevalence, compared to Asian Americans.

“We were really surprised to realize that the differences between Black and White adults are actually minuscule compared to the outliers, if you will – the categories with the lowest and highest pain levels, which are Asian Americans, and multiracial adults and Native Americans, respectively,” Zajacova said.

The racial/ethnic differences in pain prevalence were broadly similar across pain sites, including for severe headaches/migraine. For instance, Asian Americans had the lowest prevalence (10%) and Native American and multiracial adults the highest prevalence (24% and 23%, respectively) of severe headaches/migraine over the past three months. And, once again, there was little difference between Black and White groups (roughly 16.5% of Black adults reported severe headaches/migraine versus 15.5% of White adults). Hispanic adults had a prevalence of roughly 16%.

The researchers also discovered that, consistent with previous studies, women almost always had higher pain prevalence than men. And, the pattern of results held up for both sexes, with Asian men and Asian women having the lowest pain prevalence for all six pain measures, and Native American and multiracial men and women having the highest.

When looking at the intersection of sex and race, the authors highlighted some striking disparities. For instance, Native American women had roughly six times the prevalence of severe pain compared to Asian American men.

Interestingly, further analysis of the multiracial group showed that those who said Native American or Black was their main racial background had the highest prevalence of pain of any group, for all pain measures.

“People who identified as multiracial and who reported their main racial category as Black or Native American had particularly high pain prevalence. Social support networks may be a little more complicated for people who are multiracial, which trickles down to health care and mental health,” Zajacova said.

Meints said the use of the six different pain measures is a strength of the study.

“It’s really important that the authors used different categories or definitions for chronic pain, and that they found a similar pattern no matter what they were using,” she said. “One of the difficulties seen with previous research is that each study uses different criteria. These pain categories are all similar, but they’re certainly not the same, and although we see differences in the absolute values here, the patterns are similar. That’s the important piece to take home.”

How important is socioeconomic status?
The investigators next turned to the question of whether SES could account for the racial/ethnic differences. They found that lower SES among Native Americans explained their higher pain prevalence compared with White adults, but it did not explain it among multiracial adults, for whom other factors may be more important.

“This is an area of speculation, but what we are thinking is that multiracial individuals, despite the fact that this group is growing at a very rapid rate in the US, are still experiencing higher levels of stigma and discrimination, and there may be issues of identity-belonging that result in social stress,” Zajacova said.

Nor did SES explain the lower pain prevalence among Hispanics. But, Zajacova said the findings for Hispanic adults are consistent with what is known in the epidemiological literature as the Hispanic paradox, where Hispanics have lower mortality than one would expect based on their lower SES.

“The broad thinking is that lots of Hispanics are immigrants, who are in better health than native-born individuals, as sick people tend not to make a big geographic move, and they may also draw social support from families and engage in healthy behaviors like eating better,” Zajacova said. So, the finding of lower pain prevalence in this group, she continued, “fits with what we know about the health and longevity of Hispanic Americans overall.”

Another interesting finding was that Black adults had a lower pain prevalence than White adults of similar SES.

“There is a huge mental health component to health, which might explain why Black Americans report less pain, since they also report less anxiety and less depression than White Americans,” according to Zajacova.

Different settings, different questions
The current results indicating that Black, Asian American and Hispanic adults have lower pain prevalence than White adults differ from findings reported in the experimental pain literature, where those groups often have higher pain sensitivity. Zajacova said this is because the two types of investigations take place in different settings and have different outcomes.

“The experimental pain literature is important and meaningful, but it’s effectively unrelated to observing the prevalence of pain in the population, because experimental pain tests sensory, cognitive and emotional factors specific to the measures of pain threshold and pain tolerance, often in healthy people going into the lab.”

Zajacova continued, “When you’re asking a representative sample of Americans about pain, you’re getting people who have different levels of underlying health status, which you sort of equalize in an experimental setting. Population-based studies are really a different beast; you’re asking people about what they feel, not just relative to some underlying painful stimulus, but overall. So, you’re asking about different things. An experimental study doesn’t inform what’s happening in the community.”

To learn even more about pain prevalence in the community setting, researchers will have to overcome one very challenging hurdle: A striking lack of participation of underrepresented groups in research studies.

“Trying to get any minority or underrepresented group involved in research is, historically, really difficult. There is a mistrust of the research community and rightfully so,” said Meints. She pointed to the U.S. Public Health Service Syphilis Study at Tuskegee, in which the study group of Black men who had syphilis did not receive treatment even though a syphilis treatment was widely available, as one example where researchers had “really taken advantage of these marginalized folks.”

Subsequently, Meints continued, “the flipside of that is that in trying to protect marginalized groups, the pendulum swung too far in the other direction, and then we just stopped including them in research, which is just as much of a problem but in a different way.”

What’s the solution? Education and relationships.

“We need to start to understand the patients in front of us and what’s important and what they value. And we need to create relationships not just in clinical practice but in research experiments and labs. We have to make real relationships with folks in order for them to trust us and understand that we have their best interests at heart,” Meints said.

In the meantime, understanding why pain prevalence is highest in multiracial adults is a key question for future research, among many others. In addition, Zajacova told MSC that she and her colleagues have received funding for a study investigating whether different racial/ethnic groups report pain differently. She also said that it would be very important to have information about perceived racial discrimination, considering how that affects health, though this type of information is not available in NHIS.

Neil Andrews is a science journalist and executive editor of the Migraine Science Collaborative. Follow him on Twitter @NeilAndrews

References
Beyond Black vs White: racial/ethnic disparities in chronic pain including Hispanic, Asian, Native American, and multiracial US adults.
Zajacova et al.
Pain. 2022 Sep 1;163(9):1688-99.

The complexity of disparities in pain.
Stanaway FF, Campbell CM.
Pain. 2022 Sep 1;163(9):1651-52.