The science of pain is complex and its assessment subjective, leading to bias and health inequality. Now, researchers are searching for a reliable, objective measure of pain.
H
How much does it hurt? You might think it’s one of the simplest questions in health and medicine. But in fact, it can be a remarkably difficult question to answer objectively.
Consider a doctor who has two patients who are grimacing and using similar words to describe their pain. Can the doctor be sure they are experiencing similar levels of pain? What if one habitually underestimates their suffering? What if one has been in pain for a long time and grown used to it? And what if the doctor has certain prejudices that mean they are more likely to believe one patient than the other?
Pain is a difficult beast to grapple with, hard to measure and therefore to treat. Pain can be an important distress signal and failing to investigate it could mean a missed opportunity to save a life – or it may be something much more minor.
For such a universal experience, pain remains much of a mystery – especially the task of determining how much pain someone is in. “We understand it so poorly,” says Emma Pierson, a computer scientist at Stanford University researching pain. “In particular, the fact that human doctors are frequently left flummoxed by why a patient is in pain suggests that our current medical understanding of pain is quite bad.”
The gold standard for pain analysis currently relies on patients self-reporting how they feel, relying, in different places, on either a numerical scale (0 as no pain, 10 as worst pain), or a system of smiley faces.
“Step one in treating pain adequately is measuring it accurately and that’s the challenge,” says Carl Saab, who leads a pain research team at Cleveland Clinic in London. “Nowadays the standard of care is based on ‘smiley faces’ that riddle ER rooms.” This system can be confusing for patients, he says, and especially problematic when treating children and non-communicative patients.
Then there is the problem about whether the patient’s rating is believed. One study found a widespread notion that people tend to exaggerate the level of pain they are in, despite little evidence to suggest such exaggeration is common.
You might also like to read:
- The health bias rarely discussed
- Why women’s health conditions are slower to diagnose
- Nepal’s model to end domestic abuse
Without an objective way to measure pain, there is room for bias to creep into clinicians’ decisions. “Pain has a particularly large impact on underserved populations, and their pain is particularly likely to be ignored,” says Pierson.
Unfortunately, false beliefs about pain are widely held among physicians. In 2016, one study found that 50% of white medical students and residents in the US held very dangerous and false ideas about black people and their experience of pain. Another study found that almost half of medical students heard negative comments about black patients by their senior colleagues, and those students’ level of racial bias grew significantly in their first four years of medical training.
Such biases date back to historical attempts to justify slavery, including false claims that black people had thicker skin and different nerve endings. Now, black patients in the US are 40% less likely to have their pain treated than white patients. Hispanic patients, meanwhile, are 25% less likely than white patients to have their pain treated.
Racial discrimination is not the only form of prejudice that influences pain treatment. Biases around “hysterical women” are still well known in medicine, particularly around pain. A review of 77 separate research studies revealed that terms like “sensitive” and “complaining” are more often applied to women’s reports of pain. One study of 981 people found that women who came to emergency care due to pain were less likely to receive any pain relief at all, and they had to wait 33% longer than men to be treated. In addition, when men and women reported similar levels of pain, men were given stronger medication to treat it.
Social expectations about what is “normal behaviour” for men and women are at the root of these patterns, says Anke Samulowitz, who researches gender bias at the University of Gothenburg in Sweden. These biases add up to “medically unjustified differences in the way men and women are treated in health care”.
There are, she notes, sometimes genuine reasons why men and women might receive different treatment for a particular complaint. “Differences associated with hormones and genes should sometimes lead to differences in, for example, pain medication,” she says. “But all observed differences in the treatment of men and women with pain cannot be explained by biological differences.”
