Provider expectations may affect treatment outcomes

The study suggests that a health care provider’s expectations and facial expressions can affect their patient’s perception of pain. gradyreese / E+ via Getty Images

When you take medicine, your expectation about how well it will work can affect how much relief you get from your symptoms. This is called the placebo effect. It can even make a treatment that has no biological effect feel like it works because you think it will.

A health care provider’s style interacting with you can impact how you feel about a treatment. But less is known about how a doctor’s own expectations affect their patients’ symptom relief.

To test whether a clinician’s belief about a how well a treatment works affects their patient’s experience, a team of researchers led by Drs. Pin-Hao A. Chen, Tor D. Wager, and Luke J. Chang at Dartmouth College carried out three clinical simulation studies. These were designed to assess how one person’s belief about a pain remedy affects the other’s feelings of pain relief. The study was funded by NIH's National Institute of Mental Health (NIMH). Results were published online on October 21, 2019, in Nature Human Behaviour.

The studies enrolled a total of 194 students. Participants were randomly assigned to play the role of either “doctor” or “patient.” Those playing the doctor were first asked to rate their experience of pain relief after applying two creams on their arm: one called “Thermedol” and the other a control cream. The creams were actually the same. But the doctors were led to believe that one cream was effective and the other was not. They simply received a lower heat-induced pain sensation on their arm (43 degrees Celsius) after applying Thermedol than the control (47 degrees Celsius).

Next, the researchers tested whether what the doctors believed about the pain relief creams affected the patients’ experience of pain. They tested how the patients responded to a heat sensation after doctors applied the creams. But this time, both the treatment and control groups were given 47-degree temperature stimulation on their arm. The patients reported feeling less pain and showed lower responses to pain with Thermedol.

The team analyzed both the doctors’ and patients’ facial expressions using a camera and computer software that modeled painful expressions. How much pain the doctors’ facial expressions displayed affected the patient’s overall pain rating and the patients’ own facial expressions of pain. The patients also reported that the doctors seemed more empathetic when delivering Thermedol.

Similar results were found when scientists ran slightly modified experiments in two follow-up studies. These findings show how subtle social interactions can impact clinical outcomes. However, what the subtle social cues were conveying to patients is unclear. They may have helped the patients know what to expect, increased their own confidence in the treatment, or simply given them more reassurance.

“When the doctor thought that the treatment was going to work, the patient reported feeling that the doctor was more empathetic. The doctor may have come across as warmer or more attentive. Yet, we don’t know exactly what the doctor was doing differently to convey these beliefs that a treatment works. That’s the next thing that we’re going to explore,” Chang says. “What we do know, though, is that these expectations are not being conveyed verbally but through subtle social cues.”

 —by Tianna Hicklin, Ph.D.