By Samantha Kahn
Providers and researchers routinely ask patients: “On a scale from 0 to 10, how would you rate your pain?”
It’s a familiar question. But for people living with chronic pain, it’s also a frustrating one. Pain is deeply personal, and standard scales don’t always capture its complexity.
Researchers and advocates are trying to change that.
‘Nobody’s very happy’ with basic rating scales
Pain is the primary reason people seek medical care. But unlike blood pressure or temperature, it has no single objective test. That makes it difficult to evaluate treatment effectiveness, and distills the pain experience down to a number that doesn’t tell the whole story.
For decades, the 0–10 Numeric Rating Scale has been the dominant approach in both clinical care and research. “It’s pretty straightforward: 0 is no pain, and 10 is the worst-possible pain you can imagine,” explains Robert Dworkin, PhD, pain scientist and professor at the University of Rochester Medical Center’s Department of Anesthesiology and Perioperative Medicine.
But despite that seeming simplicity, “10 means different things to different people,” he points out. “Nobody’s been very happy with that. Not people with lived experience, not clinicians, not researchers, not the FDA.”
After some accrediting bodies began to require routine pain assessment in health care settings, pain scores became tied to hospital quality metrics and patient satisfaction surveys, often leading to a focus on “treating the number” rather than the person.
Where the 0–10 scale falls short
Pain scales’ subjectivity poses challenges for researchers, says Tonya Palermo, PhD, professor and vice chair for research at the University of Washington’s Department of Anesthesiology & Pain Medicine and pain scientist at Seattle Children’s Research Institute.
One person’s 3 may be another person’s 7. Someone’s scale might change day to day depending on fatigue or mood, or more permanently based on life experiences such as going through childbirth. And individuals living with daily chronic pain may have a different baseline for measuring pain.
In research settings, participants are sometimes asked to rate their pain as an average for the previous 24 hours. This leaves room for confusion, Dworkin notes, such as how to account for time spent sleeping.
Descriptive rankings (no pain, very mild, “more than mild but less than moderate”) may be a better approach in some cases, he adds.
A widely used research tool that expands on one simple rating is the Brief Pain Inventory. It includes four numerical rankings: worst and least pain in the last 24 hours, “average” pain, and pain “right now.” It also incorporates functional scales of pain’s impact on mood, activity, movement, sleep, work or school, relationships, and enjoyment of life.
Patient input has driven the measurement of additional elements as they relate to pain, such as sleep and fatigue. But in large-scale studies, detail often gets lost.
Core outcome domains for pain trials
To move past a narrow focus on pain intensity, Palermo collaborates with patient partners to identify research domains (broad categories such as pain, emotion, or physical functioning) and outcomes (specific measures of the domains, such as pain intensity, mood variation, or mobility level).
The shift toward wider-ranging pain assessments provided the foundation for the first annual meetings of the Initiative on Methods, Measurement, and Pain Assessment in Clinical Trials (IMMPACT). Dworkin and Dennis Turk, PhD, a pain medicine professor and researcher at the University of Washington, helped establish IMMPACT in 2002. Each year, researchers, clinicians, patient partners, industry members, and regulators convene to shape recommendations aimed at improving clinical trials for pain treatments.
The earliest IMMPACT meetings recommended six core outcome domains to measure the success of chronic pain clinical trials and interventions. These include not just pain itself, but physical and emotional functioning, participant satisfaction and improvement ratings, symptoms and adverse events, and participant disposition.
What’s still missing: widespread and consistent use of these recommendations across studies, says Palermo, who was also involved in shaping IMMPACT’s subsequent recommendations for core outcome domains for pediatric pain trials.
“When people use all these different scales, it’s actually super hard to tell how interventions compare, because we don’t have changes or improvements on the same outcome measures,” she explains.
Biased assessment jeopardizes care
Pain is perceived disproportionately across races and ethnicities, genders, and identities.
A 2016 study found that medical trainees even today hold false beliefs about racial biological factors influencing pain tolerance, causing some physicians to assess Black individuals’ pain as lower, and to recommend insufficient treatment.
Other studies have documented that women, people of color, and non-English speakers frequently have their pain dismissed as exaggerated or “subjective,” resulting in care that is delayed, less effective, or completely absent.
“There’s a lot of gaps right now around culture, language, and specific subgroups of the population that these scales have been used in,” Palermo explains. “We do need to focus a lot of work to make sure that these scales are as relevant as possible to every population.”
Pediatric pain: Alternative approaches
Facial pain rating scales, which use images rather than numbers or words, help children provide their own pain ratings, says Palermo, whose focus is pediatric pain. Other tools range from behavioral observation, such as changes in facial expression or body movement, to advanced facial-recognition software analyzing video of an individual’s response to a painful event.
These are useful for clinicians and researchers working with not only children and even infants, but also individuals of any age who are nonspeaking or who have cognitive limitations.
“We should make pain visible for every single patient, regardless of their status,” Palermo emphasizes.
Another significant challenge facing pediatric patients is disbelief and stigma, she says. Outdated terms like “growing pains” reinforce misconceptions that pain in children is rare, inconsequential, or temporary. Reframing medical narratives and perceptions of youth pain opens the door to nuanced assessments and deeper understanding.
Clearer views of pain: Looking ahead
In recent years, some researchers have sought to identify “objective” measures of pain through biomarkers: physical or biological indicators such as brain imaging patterns, inflammatory markers in the blood, or measures of electrical activity in the skin.
While biomarkers would add depth to pain research and treatment, Dworkin warns against relying exclusively on these measures while sidelining patient-reported outcomes and descriptions. Imperfect and inconsistent as they may be, personal accounts are still an indispensable cornerstone of understanding, believing, and treating pain.
“If the biomarker says 4 and I say 8, what do you do with that?” he says. “Pain is what the person says it is.”
Measuring pain will never be as simple as taking a temperature. But Dworkin and Palermo agree the field will continue to move toward nuanced, patient-informed assessments if pain is treated as the complex, multidimensional experience it is.
That means designing research that values patient voices; uses comprehensive, consistent, validated measures; and innovates without losing sight of lived experience.
“These are the best measures in the field right now, but they are always evolving,” Palermo says. “There’s never a single pain tool that should be used in perpetuity. We’ve always got to keep improving on this and understanding where the gaps are.”
SCORING WHAT’S SUBJECTIVE: TYPES OF PAIN SCALES
These are a few of the many scales and assessments used to measure pain in clinical practice and research:
—Numeric Rating Scale: Rate pain on a 0–10 scale, with 0 being no pain and 10 being the worst imaginable.
—Visual Analog Scale: Indicate a point along a line progressing from no pain to very severe pain.
—Verbal Rating Scale: Choose from descriptors like mild, moderate, or severe.
—Brief Pain Inventory: Describe both pain severity and functional impact (activity, mood, walking, work, sleep, relationships).
—PROMIS Pain Interference: Answer questions about pain’s impact on social, cognitive, emotional, physical, and recreational function.
—Faces Pain Scale: Select from a series of facial expressions representing a range from “no pain” to “very much pain.”
—Adult Nonverbal Pain Scale: Draws from behavioral and physiological indicators in nonspeaking individuals, such as facial expressions, movement, and vital signs.