man holding his head In the past decade, researchers have increasingly studied chronic pain epidemiology in the United States, but the research about how that pain is distributed across the country wasn’t sufficiently correcting for measurement bias. Different groups report pain differently, says Hanna Grol-Prokopczyk, an assistant sociology professor at University at Buffalo, SUNY.

Grol-Prokopczyk also noticed that most studied treated chronic pain as a binary — patients either had it or didn’t — rather than addressing severity of the pain. “I wanted to see how social disparities in pain look once you account for sources of measurement bias and for pain severity,” she says.

Her study  “Sociodemographic disparities in chronic pain, based on 12-year longitudinal data,” which is the product of several years of research, appears in the February 2017 issue of PAIN, the International Association for the Study of Pain’s journal.

The new research built upon or corrected prior studies in several key ways:

  1. Where prior research consistently demonstrated that women experience more pain than men do and that higher education and more wealth are associated with lower pain risks, Grol-Prokopczyk found that to be true, but that less-advantaged groups also experience more severe pain and more pain-related disability. “The pain disadvantage of women, the less educated, and the less wealthy is thus even greater than we thought,” she says.
  2. The new study also contradicts widely-reported research that found pain to plateau around the age of 60. By examining 12 years of data, Grol-Prokopczyk looked at pain on a longitudinal level, and she found pain to increase steadily with age, rather than to go stagnant.
  3. The most surprising finding of the study, Grol-Prokopczyk says, is that pain levels rise not only by age, but also by period. “People who were in their 60s in 2010 had higher levels of pain than people who were in their 60s in 1998,” she says. “This trend is particularly surprising given the rise of opioid prescriptions during the same period. It turns out that despite — or perhaps even because of — the huge rise in opioid prescriptions, U.S. pain levels have increased since the late 1990s.”

In her research, Grol-Prokopczyk found challenges measuring and comparing health conditions that are subjective, such as fatigue, pain, and overall health. “We know that different sociodemographic groups often have systematically different ways of rating their health,” she says, “and therefore that direct comparisons across groups can be misleading.”

If one seeks to rank countries by the way citizens tend, on average, to rate their general health in categories such as excellent, very good, good, fair, and poor, the results end up comparing apples and oranges. “You end up with a seemingly mystifying ordering that has no correlation with objective measures such as life expectancy,” Grol-Prokopczyk says. This “reporting heterogeneity” is what her new research aims to correct.

Not only does a huge proportion of the country experience chronic pain — typically moderate or severe in nature, which tends to be strongly associated with physical disability — but those who are socioeconomically disadvantaged are likelier to experience pain and pain-related disability.

“In my study, people who did not complete high school were nearly 370 percent likelier to experience severe pain than people who completed graduate degrees,” she says. “This is a huge difference.”

Physicians might be inspired by the study to reflect upon whether their clinical practices exacerbate socioeconomic disparities in pain, Grol-Prokopczyk notes.

“Previous research finds that people with low socioeconomic standing are more likely to be seen as exaggerating their pain, and to have bureaucratic hassles pertaining to health insurance,” she says. “While drug-seeking and diversion are no doubt genuine issues that doctors contend with, pain is also a widespread and legitimate problem.”

In Grol-Prokopczyk’s survey, the nearly 20,000 respondents — drawn from the Health and Retirement Study (1998-2010) — had no incentive to exaggerate their pain, she says, and yet at least 27 percent of Americans 51 years old and older reported experiencing persistent pain.

An opioid epidemic could lead many to worry about over-prescribing pain medications, but Grol-Prokopczyk stresses that pain can be addressed without worsening the former problem.

“Even if there are good public health reasons to reduce prescription of opioid analgesics (painkillers), we can simultaneously recognize the high burden of chronic pain, and seek to find better ways to prevent and manage it,” she says.

Any time there is self-reported pain, of course, there is subjectivity, but that hurdle is insurmountable in a large-scale study, according to Grol-Prokopczyk. Not only would researchers have to give each respondent an MRI scan, an expensive proposition, but there’d be no way to account for patients experiencing pain in certain positions. Patients would have to be scanned while sitting, climbing stairs, or twisting in certain positions.

“Scanners don’t permit you to sit, climb or twist, so they would miss such pain,” Grol-Prokopczyk says. “They also wouldn’t help for identifying long-term patterns in pain.”

But the subjectivity of the self-reporting, so to speak, is precisely where the new research lies. And the findings reveal the wide range of ways that different people report their pain. When men and women report “moderate” pain, for example, women tend to report more pain-related disabilities than men. “That suggests that women’s ‘moderate’ pain is actually more severe than men’s ‘moderate’ pain,” she says.