Acupuncture and blood pressure

Blogging on Peer-Reviewed ResearchHaving exhausted myself for the time being on two things that irritate me a lot (namely creationist neurosurgeon Dr. Michael Egnor and the antivaccination pseudoscience being presented as “evidence” that vaccines cause autism at the Autism Omnibus), it’s time for a change of pace. For all my tendency to deride certain “alternative medicine” modalities as pseudoscientific nonsense (homeopathy, anyone?), you may have noticed that I tend to take a softer line with acupuncture. No, it’s not because I’m a believer. Certainly, I don’t buy for a minute that somehow sticking needles in “meridians” in such a way as to “unblock the flow” of qi (life energy) does anything for serious diseases. More specifically, if acupuncture has any real effects on pain or other medical conditions, it doesn’t do it by altering any sort of mystical and unmeasurable “life energy.” If there is a physiologic effect of acupuncture, it must derive from human physiology, not magic, be it placebo effect, release of endorphins, or a counter-irritant effect, all of which have been postulated by various investigators as possible mechanisms for whatever clinical effects have been reported for it. Whatever the true case is, the scientific method should be able to figure it out in time.

A couple of weeks ago, I came across a rather intriguing study of acupuncture that proved irresistible for me to discuss; so I kept it in my folder of potential blog topics, the better to bring it out when the mood struck me. That day is today, because the article was formally published yesterday. It’s a study of the use of acupuncture in mild to moderate hypertension, and it appeared in a solid jounal, namely Circulation, which is, as I like to joke, the house organ of the American Heart Association. The study, done by a group in Germany in collaboration with a group in China, is entitled Randomized Trial of Acupuncture to Lower Blood Pressure. Here’s the abstract:

Randomized Trial of Acupuncture to Lower Blood Pressure

Frank A. Flachskampf, MD; Joachim Gallasch, MD; Olaf Gefeller, PhD; Junxue Gan, MD; Juntong Mao, MD; Annette B. Pfahlberg, PhD; Alois Wortmann, MD; Lutz Klinghammer, MD; Wolfgang Pflederer, MD; Werner G. Daniel, MD

From Med Klinik 2 (F.A.F., A.W., L.K., W.G.D.) and Institut für Medizininformatik, Biometrie und Epidemiologie (O.G., A.B.P.), Universitätsklinikum Erlangen, Erlangen, Germany; Klinikum Ottobeuren, Ottobeuren, Germany (J.G., W.P.); and Nanjing University of Traditional Chinese Medicine, Nanjing, People’s Republic of China (J.G., J.M.).

Background— Arterial hypertension is a prime cause of morbidity and mortality in the general population. Pharmacological treatment has limitations resulting from drug side effects, costs, and patient compliance. Thus, we investigated whether traditional Chinese medicine acupuncture is able to lower blood pressure

Methods and Results— We randomized 160 outpatients (age, 58±8 years; 78 men) with uncomplicated arterial hypertension in a single-blind fashion to a 6-week course of active acupuncture or sham acupuncture (22 sessions of 30 minutes’ duration). Seventy-eight percent were receiving antihypertensive medication, which remained unchanged. Primary outcome parameters were mean 24-hour ambulatory blood pressure levels after the treatment course and 3 and 6 months later. One hundred forty patients finished the treatment course (72 with active treatment, 68 with sham treatment). There was a significant (P<0.001) difference in posttreatment blood pressures adjusted for baseline values between the active and sham acupuncture groups at the end of treatment. For the primary outcome, the difference between treatment groups amounted to 6.4 mm Hg (95% CI, 3.5 to 9.2) and 3.7 mm Hg (95% CI, 1.6 to 5.8) for 24-hour systolic and diastolic blood pressures, respectively. In the active acupuncture group, mean 24-hour ambulatory systolic and diastolic blood pressures decreased significantly after treatment by 5.4 mm Hg (95% CI, 3.2 to 7.6) and 3.0 mm Hg (95% CI, 1.5 to 4.6), respectively. At 3 and 6 months, mean systolic and diastolic blood pressures returned to pretreatment levels in the active treatment group. Conclusions— Acupuncture according to traditional Chinese medicine, but not sham acupuncture, after 6 weeks of treatment significantly lowered mean 24-hour ambulatory blood pressures; the effect disappeared after cessation of acupuncture treatment.

This is actually a pretty well-designed study for the most part. It’s not without problems (more on that later), but for a study of “alternative medicine” it’s better than most. In essence, the investigators took patients with mild to moderate hypertension. Traditionally, diet and exercise are the first line of treatment for this condition. Unfortunately, human nature being what it is, patients tend to be pretty resistant to long term changes in diet and lifestyle. Most will start out all enthusiastic and may even stick with it for a while, but there is a strong tendency to backslide, which is one reason ultimately so many patients end up on medication (the other is that diet and exercise are not enough for a significant proportion of mildly hypertensive patients). It should be pointed out that the reason that the investigators studied patients both on and off medication was that they deemed it unlikely that they could recruit enough hypertensive patients not on any medication to have adequate statistical power to detect effects on blood pressure. Once patients were recruited, they were subjected to a randomization scheme that was meant to make both groups similar in ranges of blood pressure, antihypertensive use, age, and a number of other parameters.

The next point about this study is how the acupuncture was administered. There’s a detailed description of the points used. The investigators brought in highly experienced Chinese practitioners who also had studied Western medicine (whatever that means these days) to administer the acupuncture. Patients were assigned to 1 of 4 types of hypertension according to criteria of traditional (TCM). This, of course, begs the question of how these criteria came to be, if TCM is such an “ancient” medical art. After all, a couple of thousands of years ago, the concept of blood pressure was not known, much less that having elevated blood pressure was a bad thing. Indeed, it wasn’t until 1901 that Harvey Cushing introduced a version of the blood pressure cuff into clinical practice in the U.S., bringing the device, which had been invented in Europe a few years before by Scipione Riva-Rocci. In fact, this device was not initially accepted, because it was different from the previously widely used method of palpation of arteries to judge the quality of circulation. It took until 1910 for the device to catch on to the point where nearly every patient in the hospital had his or her blood pressure monitored. It was not until decades later that the longterm risks of hypertension were widely appreciated. So, why would ancient Chinese practitioners care about lowering blood pressure? Alas, the work referenced was a book from 1999 on Chinese acupuncture and was thus not accessible to me. At least the randomization was done by a Chinese physician unaware of which experimental group each subject was in.

But I digress.

Getting back to the study, based on the “type” of blood pressure each patient was judged to have, patients in the treatment group would receive what the TCM practitioner recommended. Patients in the control group would receive “sham” acupuncture, which involved sticking them with the same number of needles, just not in the “right” spots. Sham acupuncture was administered to control subjects in the same way regardless of the “type” of hypertension. Another aspect of the acupuncture given is that each session took 30 minutes, and patients started with 5 sessions a week, tapering to 3 sessions a week later in the treatment period.

In essence, the results are as described in the abstract. The difference between treatment groups was 6.4 mm Hg and 3.7 mm Hg for 24-hour systolic and diastolic blood pressures, respectively. For those receiving acupuncture, the mean 24-hour ambulatory systolic and diastolic blood pressures decreased significantly after treatment by 5.4 mm Hg, respectively. Although the number of patients not taking antihypertensive medicine was small, the pattern was similar but appeared somewhat more heterogeneous. Of note, the treatment effect disappeared after the acupuncture was stopped.

This study raises a number of interesting issues and poses some problems. First, although the decrease in blood pressure was significant and comparable to what angiotensin converting enzyme (ACE) inhibitors produce. However, I was struck at the seeming difficulty and impracticality of it all. We’re talking about at least three sessions a week of a half hour each session. If patients have a tendency not to be compliant taking pills, one has to wonder how compliant patients would be with such an acupuncture regimen. Moreover, this study was done under very controlled conditions with a population free of significant disease other than arterial hypertension. People with heart failure, evidence of heart damage, or evidence of kidney disease were excluded.

One problem is that the control “treatment’ is not necessarily physiologically neutral. “Sham” acupuncture, in which the needles are inserted to the same depth as acupuncture for treatment, has long been a problematic control. Indeed, as an accompanying editorial pointed out, as many as 40%-50% of patients subjected to sham acupuncture experience some degree of analgesia, and even in non-pain conditions, needling in non-acupuncture points may produce physiologic effects. Indeed, if you look at Figure 3 in the paper, you’ll find something very interesting:

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(Click to see a larger image at the Circulation Research website.)

I noticed two things. First, the acupuncture group had a wider variation in its pretreatment blood pressures. Second, the sham acupuncture group consistently seems to have a slightly higher blood pressure, as evidenced by a positive difference to baseline. The editorial also alluded to the possibility that sham acupuncture might actually been slightly increasing blood pressure in the control group. It was also pointed out that regression to the mean might lead one to expect that, even in the absence of treatment, blood pressures might be expected to be slightly lower at six weeks. Does that mean that that’s what happened? We don’t know.

Perhaps the biggest problem with this study is a problem that all studies on acupuncture suffer (and, I must admit, that nearly all surgical clinical trials suffer from also) is the impossibility of double-blinding and the control group. The patients may have been blinded to the experimental group that they were in, but the practitioners were not. Practitioners were blinded to blood pressure but not to treatment. Remember, these are TCM practitioners who really believe in acupuncture. It’s quite possible that, because they believe acupuncture to be effective the practitioners administering sham acupuncture may have given off subtle signs of discomfort at administering a form of acupuncture that they believe to be useless. Also, because they were not needling points that they normally used, they may have been less sure of themselves than usual, at least in the beginning. Blood pressure is quite sensitive to emotional state; so it’s not outside the pale to wonder whether patients picked up on this and if it had an effect. It is also not clear whether the assessors measuring blood pressures were fully blinded to patient treatment group.

So, what does this study tell us? Not much. Acupuncture might be mildly effective in reducing blood pressure in uncomplicated mild to moderate hypertension through an as yet unknown physiologic mechanism, but it requires considerable investment in time, with half-hour sessions done multiple times per week, making it more difficult a treatment regimen to adhere to than most antihypertensive treatment regimens. Even if this research pans out and the results of this study are replicated and extended, it doesn’t appear to me that acupuncture would be all that useful in the general population, other than in a subset of highly motivated patients willing to let TCM practitioners stick needles in them for a half hour three times a week indefinitely. Personally, if I ever end up needing treatment for hypertension (and my diastolic pressure is sometimes borderline), I’d probably take medication and use a half hour three times a week to go to the gym–something I probably should be doing anyway.