This study provides support for the hypothesis that the effectiveness of acupressure bands in reducing nausea can be enhanced through an expectancy manipulation, but it comes with the qualification that such manipulations should be targeted. Our expectancy manipulation resulted in improved control of nausea in patients with high nausea expectancies but lessened control of nausea in patients having low nausea expectancies. This interaction effect approached statistical significance for our analysis of Average Nausea and reached statistical significance for our analysis of Peak Nausea, even though this was a small pilot study.
Understanding that a medical intervention is appropriate for some people but not all is basic to the practice of medicine, and researchers endeavor to find out not only if an intervention is effective, but also for whom it is effective. The present study provides important data regarding both objectives. Our findings support the use of expectancy-enhancing information as an aid to nausea control, at least when acupressure bands are used, and also provides initial evidence that such information may be beneficial only to patients expecting to have nausea. In very simplistic terms, it is as if a negative expectancy for nausea held by a patient can be neutralized by providing an expectancy-enhancing intervention regarding nausea control. We note that negative expectancies such as those for nausea targeted in this study are significant predictors of actual nausea, as detailed in the introduction. Nausea, in turn, is a particularly significant problem in breast cancer patients receiving chemotherapy, the patient group for this study.8
Our intervention also affected the amount of antiemetic medication used; patients who received the expectancy-enhancing information took significantly less than patients who received the expectancy-neutral information. Thus, it appears that in the group of patients expecting nausea, the intervention had a double effect for those receiving the expectancy-enhancing information. This group not only experienced less nausea but also used less antiemetic medication compared to patients who received expectancy-neutral information. It is also possible that the difference in medication use between intervention arms affected nausea levels in the group of patients not expecting nausea and accounts for the increase in nausea in patients receiving the expectancy-enhancing information compared to patients who did not.
The reduction in antiemetic use may have been an unintended consequence of our expectancy-enhancing handout, specifically, the prescription to use the acupressure bands for relief of nausea. Even though a sticker was placed on the prescription with the instruction to use the bands in addition to their antiemetic medication, patients may have reduced their antiemetic use thinking the imprimatur of a doctor’s signed prescription to use the acupressure bands meant the bands alone would control their nausea. Further studies should be done using the expectancy-enhancing materials without the prescription to see if these materials also reduce antiemetic use when used alone. Future studies should use a study design that more rigorously specifies the antiemetic regimen.
While acupressure bands and a relaxation CD were used in this study, our data cannot speak to their actual efficacy because all patients received them. We do know they were well-received and used extensively by most patients. Most of the patients in the study also indicated they would recommend their use to other patients.
A plausible explanation for how expectancies affect nausea is that a patient expecting nausea following chemotherapy might be more likely to interpret vague or ambiguous sensations as nausea than an individual not expecting the symptom.32
Theoretical support for this explanation comes from schema theory which holds that cognitive schemas act as information processing systems that filter and interpret new data, with greater attention being paid to schema congruent information.33–35
In this sense, a nausea expectancy can be considered a schema that can override sensory information.36
As stated by Posner, “The idea that perceptions can be manipulated by expectations is fundamental to the study of cognition.”36
Expectancies, when positively oriented, are at the core of theories attempting to explain the placebo effect.7,37
Stewart-Williams describes the placebo effect in its classic form as beginning with an expectancy or belief: i.e., if I take drug X
, I will experience effect Y
Taking the drug, or something the patient thinks is the drug, then produces the placebo effect. Price and colleagues8,39
report a shifting of understanding and conceptualization of the placebo effect from a focus on the inert content of a physical placebo agent to the overall simulation of a therapeutic intervention. In this broader context, it is understood that the placebo effect occurs not only with drugs and fake drugs, but also with any medical intervention (e.g., a mother’s kiss on a boo-boo). It is also the case that the magnitude of a placebo effect may not be constant and can be enhanced under certain circumstances as shown by Wise et al,13
discussed earlier, and others.40–42
Several studies have shown that information given to patients about a treatment can modify their expectations and thus their response to that treatment.36,43–46
Crow and colleagues in their review of the role of expectancies in the placebo effect state that “the existing evidence justifies the use of strategies to enhance expectancies, specifically to enhance patients’ beliefs in the benefits of effective medical treatments.”47
Our findings lend support to this statement but add a caution that such interventions might be helpful only to patients who have negative response expectancies. If our findings are affirmed in subsequent studies, it would underscore the importance of two-way communication between patients and medical service providers and the need for clinicians to be mindful of patients’ expectations regarding symptoms. As most patients regard their medical professionals as knowledgeable authority entities, those patients holding negative expectancies might benefit from a more tailored communication approach that integrates information about patients’ expectancies regarding symptoms.
Limitations of the study include a small sample size and the fact that we ceased recruitment to two of the treatment arms and changed our planned primary analysis mid-study based upon an interim analysis that was not specified at the time the study began. Even though the data collected following the interim analyses closely matched the data collected before it, our findings need to be considered tentative until replicated. Because this was a small exploratory study, we did not adjust our P values for the multiple comparisons (three total) nor for the interim analysis.
These are additional reasons why our findings need to be considered tentative until replicated. Patient differences in the type of chemotherapy provided could have affected our findings despite our use of a stratified randomization schema. Similarly, differences in the kind of antiemetic medications provided, both in the clinic and for home use, could have affected study outcomes. Given that nausea expectancies are malleable, it is possible that differences in the various providers’ discussions with patients regarding nausea management could have influenced outcomes. Our randomization procedure should have adequately controlled for these factors, but it may not have. An additional study limitation is that we do not know the relative effect of the expectancy-enhancing handout vis-a-vis the expectancy-enhancing CD. Nor do we know if both are needed for a beneficial intervention effect to occur. Future studies should control for these limitations, if possible, and also include a standard care control group.
Despite general acceptance that nonspecific treatment factors such as response expectancy play an important role in health-related outcomes, relatively little randomized, controlled research has examined their effects. This is likely due in part to the abstract nature of response expectancies and the methodological difficulties that come with measuring them. Another impediment is that non-specific treatment factors, such as expectancy, are often regarded as an unquantifiable nuisance or are bundled as part of the “placebo effect,” something that randomized trials “control” for and attempt to show effects beyond. Although controlled trials clearly have their place in medical science, the element we control for in such trials, i.e., the placebo effect, may, nevertheless, be a construct that can be harnessed for improved patient well being.