The results from this study support our pre-study hypothesis that a hypnosis intervention does significantly reduce hot flashes. The effect size was large, and a 68% reduction in hot flash scores indicated a clinically significant reduction. Satisfaction with the hypnosis intervention was favorable, and none of the patients complained or dropped out of treatment because of any negative adverse effects. This is generally consistent with our previous impressions from case studies of hypnosis for hot flashes7,8
and with research on hypnosis for symptom management, and it suggests that hypnosis is a well-tolerated intervention for most patients.16-18
Some criticism of this study is that observations were limited to 5 weeks and that it does not provide data regarding long-term follow-up. However, a ≤ 5-week time period has been used in a series of clinical trials that assessed pharmacologic therapies for alleviating hot flashes in breast cancer survivors, and it does allow comparison.5,19-23
Our anecdotal experience has given us reason to believe that patients who continue to practice self-hypnosis continue to benefit with maintenance of reductions.8
Subsequent studies should use a longer-term follow-up period to determine if sustained symptom relief is achieved with hypnosis.
Although it could be argued that physiologic monitoring of hot flashes is needed to validate the reduction of hot flashes, the use of self-report diaries, as used in this study, has long been established as a valid approach to obtain data on subjective phenomena, such as patient-reported symptoms.19,20,24-26
Self-report diaries have been used in the majority of studies of interventions for hot flashes, and they provide the advantage of data about severity.14
Nonetheless, there may be some clinical utility in using physiologic recordings in clinical trials to gain a better understanding of the mechanism of action and the physiologic impact of hypnosis on hot flashes.
It has been established previously that women with unrelieved hot flashes suffer negative emotional consequences, such as anxiety, depression, interrupted sleep, and decreased quality of life.2,3,27
It is reasonable to hypothesize that interventions that effectively relieve hot flashes would also result in improved mood, affect, and daily activities, including sleep. Women who received the hypnosis intervention in this study did, in fact, report significant improvement on each of these secondary outcomes. Not surprisingly, on enrollment, participants reported significant interference with daily activities as a result of their hot flash experiences. HFRDIS total scores range from 0 to 100. The mean baseline HFRDIS score for the treatment group was 39.52; in contrast, the post-treatment HFRDIS scores were significantly lower than pretreatment, and the mean score was only 10.42. Therefore, this study suggests that hypnosis for hot flashes has additional side benefits that include decreased interference with daily activities and quality of life.
In terms of anxiety, the mean HADS score at baseline was below the cutoff score reported in the literature that indicates possible clinically relevant anxiety. The women who participated in the hypnosis intervention group reported significant reductions in anxiety, which supports the concept that hypnosis to treat hot flashes is also effective to alleviate even subclinical symptoms of anxiety.
However, the reason for these benefits is not entirely clear. Individuals who have negative affect (eg, anxiety, depression) may be more likely to attend to and to report physical symptoms,28
and/or unrelieved hot flashes may result in more frustration and negative consequences.14,27
In either case, this study suggests that the effect of hypnosis is to improve emotional and psychosocial adjustment of women who experience hot flashes.
The mechanism of action of hypnosis to reduce hot flashes is unknown, and this question was not addressed in this study. A substantial placebo effect has been observed in multiple hot flash studies.14,19,20,22,29-33
On average, hot flash frequencies diminish by 20% to 30% with 4 weeks of placebo.14
Also, evidence from other studies suggests that women may tend to under-report hot flashes.34
The feeling of security that results from a mind-body intervention, such as hypnosis, may reinforce this tendency. It is generally accepted that treatments that result in hot flash score reductions of less than 40% should be considered consistent with placebo effect; therefore, interventions that result in hot flash score reductions of greater than 50% should be considered greater than would be expected from placebo.14
These study findings indicate that hypnosis is likely to reduce hot flashes to a greater degree than placebo, by 68%. In this study, the mean number of hot flashes, regardless of severity, exceeded seven per day at baseline. Women who received the hypnosis intervention reported an average reduction of 4.39 hot flashes per day, whereas the women in the control group remained relatively unchanged. It is interesting to note that we did not observe the placebo effect for self-reported hot flashes that is typically observed in clinical trials. This outcome most likely is because the control was a no-treatment condition, which is consistent with findings that hot flashes remain stable over time if left untreated. However, given the percent reduction in hot flashes, the effectiveness of the hypnosis intervention would likely hold up against a parallel arm. A randomized clinical trial is currently underway by the authors to compare the hypnosis intervention to a placebo control and to additionally address the possible underlying mechanisms (eg, stress, serotonin).
Seasonal effects are unlikely to account for findings in this study, because the study intervention occurred during a period longer than 1 year and because the effect size was large. Another concern could be the possible use of other complementary therapies. Patients in this study were required to discontinue all other treatments for hot flashes, with the exception of vitamin E, which has had limited efficacy in relieving hot flashes.21
Women are interested in alternatives to traditional hormone therapy and pharmacologic interventions, and this study demonstrates the feasibility and potential effectiveness of hypnosis as an alternative treatment. However, certification in the professional use of hypnosis requires considerable training13
and practice. Also, some patients may not be good candidates for hypnosis. For example, hypnosis should be avoided or should only be used with caution in patients with a history of severe psychopathology (eg, borderline personality disorder, schizophrenia, post-traumatic stress disorder).35
Also, it is possible that some patients may be in the low range of hypnotizability and, as a result, may benefit less. Future studies should assess these variables. Despite these limitations, it has been our impression that most patients can benefit from hypnosis. However, long-term, randomized, placebo-controlled studies will be needed to identify the long-term effect and integrative role of hypnosis in the treatment of hot flashes.