Pain is a tricky thing to evaluate. Measures such as the Comparative Pain Scale that ask patients to rank their own pain from 0-10 gather strictly subjective data. Healthcare professionals are cautioned that pain is an individual phenomenon, and numerous studies have observed cultural and gender differences, amongst others, that influence how patients express and rate their pain.
The health care practitioner’s independent assessment is crucial to avoid over- or under-medicating or treating the patient who is faking pain in order to feed a drug addiction. But a new study adds to existing literature that indicates the care provider’s assessment is not necessarily objective.
“When you dislike patients, pain is taken less seriously.” That is the straightforward title of a paper published in the journal Pain (Oct. 2011) that has twice captured the attention of F1000 evaluators: Craig Webster from the University of Auckland, and Joel Katz and Samantha Fashler from York University in Toronto.
The study enlisted 40 healthy volunteer observers to rank the likeability and then the pain levels of six shoulder-pain patients. First, volunteers viewed headshot photos of the three male and three female patients, which had been tagged with three-word labels that cast their character variously in a negative, neutral, or positive light. The labels were “egoistic, hypocritical, arrogant,” or “true to tradition, reserved, conventional,” or “faithful, honest, friendly.”
Next, the volunteers observed video that had been shot during physiotherapy sessions where the patients performed pain-inducing movements. Based on the patient’s facial expressions, the volunteers rated their pain, from none, to mild-intensity, to high pain.
Sure enough, those supposedly egoistic, hypocritical, arrogant patients were deemed less likeable than patients associated with neutral traits, who were in turn rated less likeable than those “faithful, honest, friendly” folks.
And when those least-liked patients expressed high-intensity pain, volunteers estimated it to be less intense than the high-intensity pain expressed by the well-liked patients. Katz and Fashler note:
The authors interpret this effect as arising from observer suspiciousness; the more severe the pain display in unlikeable patients, the more likely observers are to attribute the pain to malingering or exaggeration. Another implicated mechanism was empathy, whereby observers might have more similar brain activation patterns to the patient’s patterns when the patient is more likeable.
The researchers note that their study confirms others that have found that higher pain, disability, and distress scores are attributed to well-liked patients. But they also acknowledge some limitations of this particular research. One is that the volunteer observers were laypeople, not professional caregivers. Another is that only facial expressions, not the body or shoulder were observed in the video.
Katz and Fashler suggest that
future studies should replicate this design using health care professionals with varying levels of experience as participants to evaluate whether unlikeable patients are rated as having less pain than likeable patients and to see whether this effect is altered with increasing clinical experience.
In the meantime, as Webster notes, the study indicates “a significant bias that pain clinicians must be aware of in order to adequately treat patients in pain.”