(Photo by Ryutaro Tsukata)
Clinical equipoise means that clinicians and researchers honestly don’t know which treatment is better. Therefore, no researcher favors one treatment over another during the experiment design, which reduces the risk of bias.
If one treatment is already known to be better, it would be unethical to give someone the inferior treatment just for research. However, if no one really knows which is better, it is okay to randomly give people different treatments to find out.
For example, imagine a study in massage therapy where some people with low back pain get a Swedish massage and others get a lomi lomi massage. If experts disagree about which is better, that is clinical equipoise. It is fair to run the study because no one is sure which treatment is better.
Despite being called the “golden standard” in research, the randomized-controlled trial (RCT) method is challenging to design for clinical equipoise for several reasons.
First, blinding is difficult because massage and other manual therapies require the therapist to be in physical contact with the participant. The therapist obviously know which treatment they are giving, and participants may know whether they’re getting a real massage or even the specific type of massage. This can create expectation bias—participants might feel better simply because they believe the massage will help (placebo effect).
Second, standardizing massage therapy is complex because massage is a hands-on and personalized treatment. Therapists use different techniques, levels of pressure, stroke speed, and time, which makes it difficult to keep every movement and procedure consistent. This lack of consistency can affect how reliable the study results are.
Third, creating a sham massage is tricky. Unlike a sugar pill in drug studies, light touch or superficial massage can still have positive effects on the participants, making it hard to tell whether any benefits are from the treatment itself or just from being touched.
Finally, the context around massage—such as calming music, a peaceful environment, the smell of the sheets, and the human connection—can influence how people feel. These confounding factors make it harder to know if people are feeling better because of the massage itself or because of the relaxing experience that comes with it.
Researchers Brian Dewar, Michel Sharny and their colleagues wrote in their 2023 study that RCTs are “risky” because they “remove decision-making power from the patient and [their] physician, and may require patients to receive a treatment that is ultimately found to be inferior to its comparator, or to standard care.”
While clinical equipoise is a foundation in research ethics— especially for randomized-controlled trials (RCTs)—sometimes biases leak into the experiment during the experiment design, especially in manual therapy.
Ethicsin clinical equipoise indicates if there is already certainty about a treatment, then a study should not be done. If a treatment has uncertainty, then a trial may be done. (Image by Nick Ng)
Dr. Chad Cook of Duke University School of Medicine and data scientist and physiotherapist Charles Sheets wrote in The Journal of Manual & Manipulative Therapy that “some placement of importance, enthusiasm, or confidence associated to one’s expertise in an intervention” would play some role in the experiment’s outcome.
Cook and Sheets added that personal equipoise should be also considered in research design, which is “when the clinical service provider (or clinician) involved in the research study has no preference or is truly uncertain about the overall benefit or harm offered by the treatment…In other words, the clinician has no personal preconceived preferences toward the ability of one or more of the interventions to have a better outcome than another.”
However, they pointed out that most RCTs have “migrated toward directional hypotheses,” which is intended to prove one method is better than another.
“One of the reasons for this change is publication bias, which is the tendency for journals to accept papers for publication based on the direction or strength of the study findings,” Cook and Sheets wrote. “Studies have a higher likelihood of being published if they show a significant difference between groups.”
Thus, publication bias may exaggerate an intervention’s effectiveness. For example, a 2023 review identified eight clinical trials “key concerns” that skew the results of 32 systematic reviews and 10 clinical practical guidelines for spinal pain. The interventions examined were cognitive behavioral therapy and physiotherapy exercise.
When the researchers removed these eight trials, the effect size was reduced by an average of 58%.
How manual therapy RCTs are typically done
According to Cook and Sheets, researchers usually compare two types of treatments. The first type compares specific techniques, like joint movements or nerve stretches, often based on a certain therapy style. The second type compares whole systems or methods, like McKenzie versus orthopedic manual therapy. Most of the time, the therapists doing the treatment are trained in just one of the methods, and they often feel more confident or excited about the one they know best.
That confidence—whether they realize it or not—can affect how well the treatment works.
“When the results of a study support a clear pre-study directional hypothesis, (particularly one that supports the authors’ previous line of research) interpretation of the results should include analysis about a potential conscious lack of equipoise,” Cook and Sheets wrote.
Also, they wrote that almost every manual therapy method has been used both as a real treatment and as a “fake” or sham treatment in studies. A technique might work well when done by one trained therapist but have no effect when done by someone who doesn’t use it the same way.
How could massage therapy research improve?
Massage and manual therapy RCTs can still be done with minimal biases. Cook and Sheets suggested a few ways to improve equipoise in manual therapy RCTs.
One way is to assign patients to specific clinicians rather than just assigning them to a treatment. For example, patients in a trial comparing Swedish massage to lymphatic drainage massage for chronic pain among breast cancer patients could be treated by therapists who specialize in each approach.
“Ideally, this would involve practitioners of similar levels of training, and include multiple therapists in each group,” Cook and Sheets wrote. “This would increase the likelihood that the variable examined is the technique or method rather than the skill of a particular clinician.”
Another approach he proposed is the equipoise-stratified design, which takes into account therapists’ preferences for certain treatments before the trial begins. By balancing these biases across the study groups, the design aims to reduce the influence of those preferences, especially in studies involving multiple or complex treatments.
A third option is the clinician’s choice design model where therapists choose from approved treatments based on what they think is best for each patient. However, this can make group sizes uneven and weaken the randomization, which can make it harder to tell what really caused the outcome, they concluded.
Cook and Sheets wrote that if none of the previous three designs are used, researchers can still adjust statistically after the study by including therapists’ confidence or preference in one treatment as a factor in the analysis. While this is the weakest form of bias control, it’s better than doing nothing and should be the minimum standard in massage therapy trials.
“Until clinical equipoise is clearly accounted for, studies at risk for violating equipoise should be interpreted with caution,” Cook and Sheets wrote.
Nick Ng is the editor of Massage & Fitness Magazine and the managing editor for My Neighborhood News Network.
An alumni from San Diego State University with a bachelor’s in graphic communications, Nick also completed his massage therapy training at International Professional School of Bodywork in San Diego in 2014. In 2021, he earned an associate degree in journalism at Palomar College.
When he gets a chance, he enjoys weightlifting at the gym, salsa dancing, and exploring new areas in the Puget Sound area in Washington state.
