If you ever want to wonder why I’m sometimes of the mind that the National Center for Complementary and Alternative Medicine should be disbanded and its functions distributed among the other Institutes of the NIH, you just have to consider the sorts of woo-filled studies (like the Gonzalez protocol) funded by NCCAM mixed in among the more reasonable studies of herbal remedies and other modalities that have at least a modicum of scientific plausibility. With that in mind, I came across a study that seems to be getting a fair amount of play in the press, at least around here. The study purports to demonstrate that Tai Chi boosts the immunity to varicella zoster, the virus that causes shingles, in the elderly. Sounds great, right? Unfortunately, that’s not exactly what it really appeared to show. You’ll see what I mean, but first the abstract:
OBJECTIVES: To evaluate the effects of a behavioral intervention, Tai Chi, on resting and vaccine-stimulated levels of cell-mediated immunity (CMI) to varicella zoster virus (VZV) and on health functioning in older adults.
DESIGN: A prospective, randomized, controlled trial with allocation to two arms (Tai Chi and health education) for 25 weeks. After 16 weeks of intervention, subjects were vaccinated with VARIVAX, the live attenuated Oka/Merck VZV vaccine licensed to prevent varicella.
SETTING: Two urban U.S. communities between 2001 and 2005.
PARTICIPANTS: A total of 112 healthy older adults aged 59 to 86.
MEASUREMENTS: The primary endpoint was a quantitative measure of VZV-CMI. Secondary outcomes were scores on the Medical Outcomes Study 36-item Short-Form Health Survey (SF-36).
RESULTS: The Tai Chi group showed higher levels of VZV-CMI than the health education group (P<.05), with a significant rate of increase (P<.001) that was nearly twice that found in the health education group. Tai Chi alone induced an increase in VZV-CMI that was comparable in magnitude with that induced by varicella vaccine, and the two were additive; Tai Chi, together with vaccine, produced a substantially higher level of VZV-CMI than vaccine alone. The Tai Chi group also showed significant improvements in SF-36 scores for physical functioning, bodily pain, vitality, and mental health (P<.05). CONCLUSION: Tai Chi augments resting levels of VZV-specific CMI and boosts VZV-CMI of the varicella vaccine.
So just doing Tai Chi for 16 weeks boosts immunity to varicella, apparently, if this study is to be believed.My first thought in seeing this study was to wonder why on earth the investigators came up with the hypothesis that (1) Tai Chi might boost immunity to varicella zoster and (2) that it would improve response to the vaccination. Did they see old people doing Tai Chi not getting shingles as often? Are they using immunity to varicella as a convenient marker for general immunity? Did they just pull the hypothesis out of their behinds? Inquiring minds want to know! And where on earth did they get the idea to give VZ vaccine at the end of the study period? True, they mentioned how immunity and response to vaccines in general are not as robust in the elderly and that they were looking for ways to boost immunity
So let’s look at this study. I’ll give the investigators props for at least randomizing their studies. That makes it better than at least 90% of “alternative medicine” studies out there. Heck, that makes it better than probably 99% of alternative medicine studies out there. But randomization alone does not make a good study. Equally important is what the experimental groups are and what the control is. So what, exactly, are the experimental groups, both of which are only briefly mentioned in the abstract. Let’s take a look at the Methods section of the paper (note: TCC=Tai Chi; HE=health education):
Subjects received 16 weeks of TCC or HE administered to groups of seven to 10 persons. TCC sessions lasted 40 minutes and were given three times per week for a total 120 minutes of weekly instruction. HE was also allocated a 120- minute period of instruction per week, an identical amount of instructor time as given to TCC. The rationale communicated to subjects was that TCC is a health management intervention that incorporates meditation and repetitive physical activity to promote well-being in aging, whereas HE aims to promote healthy behaviors and well-being by providing knowledge about health management. For TCC, objectives and learning activities related to the specific set of 20 exercises employed were identified according to a therapist manual,29 with verification of skills attainment and weekly supervision by master’s level TCC instructors. The HE intervention involved 16 didactic presentations on a series of health-related themes provided by a physician or licensed clinical psychologists with group discussion, as previously described.30 Treatment credibility and expectation were assessed for change after the second treatment session using a 5-point Likert scale.
Now do you see the problem?
Let me submit to you that I believe that the results are probably valid, even though the subjects were not blinded. For one thing, blinding the subjects of a study like this to the experimental group is virtually impossible anyway; so this is probably the best design that can be done. I believe that Tai Chi in this study actually did modestly boost the measures of immunity studied and the response to the VZV. But that is not the same thing as believing that Tai Chi has any special properties. What I submit to you is that what was really being studied here were two groups, one of which underwent regular, mild exercise (Tai Chi), and the other of which basically sat on their behinds in a class for the same period of time. In other words, the result is not at all surprising. After all, there is a fair amount of literature to suggest that exercise improves immune function in the elderly. Tai chi is nothing more than an exercise regimen, with some meditation thrown in. Why wouldn’t it have similar effects? If the investigators really wanted to see if Tai Chi had any special properties, at least two more control groups would be needed. One of these could be a group that did mild exercise, like walking, to the same estimated level as the Tai Chi regimen. The other could be a “sham” Tai Chi group, in which the participants were told that they were doing Tai Chi but were being led in the “wrong” moves. Heck, if they really wanted to get fancy, they could have separated the meditation and exercise components of Tai Chi and study them.
Maybe I’m just in a bad mood. Maybe I’m just too cynical. Maybe I’m being too harsh on this study, but the whole thing irritates me. My guess is that, had this been a simple study of mild exercise and immunity in the elderly, it wouldn’t have gotten nearly the play that it did. Heck, I’m not even sure it would have been funded in these days of extremely tight NIH dollars. Moreover, contrary to some of the blogospheric commentary, this study most assuredly did not show that Tai Chi prevents shingles; no differences in the incidence of shingles or severity of attacks was studied, and, as the authors pointed out, the increase in antibody response does not correlate reliably with immunity to shingles. But Tai Chi is popular and associated with “alternative” medicine. It’s also associated with woo:
Zhang Gao, a Chinese Kung Fu 6th Duan master who is the 2006 USA National Champion winning four Gold medals and one Silver medal, told foodconsumer.org that among other things Tai Chi helps the flow of vital energy called Qi, which is believed to be responsible for health benefits. Mr. Gao used Qi to effectively treat patients with colds, stomachache, headache, high blood pressure and other illnesses in China. Gao now runs a martial art school in St. Louis teaching a variety of Chinese Kung Fu styles including Tai Chi and Qi Gong.
Of course, whatever benefits Tai Chi has or does not have, they are not due to alterations in qi or any other “vital energies.” They’re almost certainly due to the duller and more prosaic explanation that it’s physical activity. Of course, I’m guessing that it’s because of the woo that Tai Chi gets studied because it’s a “sexier” subject, when in fact it’s pretty likely that any mild-to-moderate exercise would have produced the same results.