Oct 16 2008
Recently several chiropractors have been posting comments on this blog, under the blog entry about a law suit over a stroke allegedly due to a chiropractic neck manipulation. A detailed-enough response to the several long comments is worthy of its own entry, so here it is.
First, I want to point out that I greatly appreciate when readers post contrary opinions on my blog. Agreement (while also appreciated) is boring and does not advance the discourse. If I am missing an important piece of information, or my logic is flawed, I love having it pointed out – that way I can make corrections. I want my arguments to be both valid and as complete as possible, so corrective feedback is very valuable.
I also greatly enjoy sparring with those who have used logic and evidence to come to a different conclusion from me. A constructive discourse can only be a learning experience all around. I find I understand a topic much better after having to defend my position to someone adverse to it and who is using every argument they can muster to take it down.
Even those who are closed-minded and ideological can serve a purpose, if only as a spur to discuss real science, and as an example of how thinking can go wrong (creationists are the poster-child for this, but there are plenty of examples).
The chiropractors who have posted here recently bring up many common points, and so readers are likely to encounter them elsewhere. “Cause and Effect” writes:
Yet, many posts could be quoted to the “Anecdotal” nature of us Chiropractors. In MY OPINION, if you were a true scientist, you would commend these anecdotes and suggest further research, rather than write them off as here-say and folly. All good scientists produce their proof or lack-there-of from a single thought. Such was the case in the early 1900’s with the advent of medication to relieve ailments. It began as a thought, was promoted by those in business and has remained as such since.
A certain red flag for medical quackery is the unqualified defense of anecdotal evidence. It is an appeal for a lower quality of evidence to trump a higher quality of evidence, and significantly downplays the serious limitations of uncontrolled observations. Cause and Effect defends it by attacking a straw man – that my position is that anecdotal evidence is all written off as “folly” and should not even be used as a basis for further research.
I have written a thorough entry just on this topic over at Science-Based Medicine, called The Proper Role of Anecdotes in Science-Based Medicine. Briefly, I acknowledge that anecdotal observations are properly used as a starting point for generating hypotheses that can later be tested by controlled experiments. However, they are too low-grade a type of evidence to be used as a basis for a scientific conclusion. Promoters of unscientific medicine are often profoundly confused about the difference between generating hypotheses, and forming conclusions upon which it is reasonable to base therapies.
Another consideration that must be added to anecdotal observations in generating hypotheses is plausibility. Not all ideas in science are equal. Prior probability is an important consideration in determining how scarce research resources should be allocated, and also in what experimental therapies to which it would be ethical to subject patients.
But also notice the common ploy Cause and Effect uses of framing their position as just advocating for research – what can be more reasonable than that – and trying to say that I am not scientific because I am against more research. There are many problems with this position, however. First – I recognize the utility of anecdotes in deciding what is worthy of research (put in the proper context of plausibility), so it is a straw man. Second, there has been research on many of the basic premises of chiropractic and specific therapies. True-believers simply ignore negative evidence and endlessly call for more research – it’s nothing more than a ploy to keep the game going for as long as possible.
The last sentence regarding medication is also very telling: “It began as a thought, was promoted by those in business and has remained as such since.” Cause and Effect is missing an important step in this process – testing the “thoughts” with well-controlled clinical trials to see if they are actually true. Most are not.
Cause and Effect writes:
For example, If you were to witness for yourself a patient with any of these conditions change at the hands of a Chiropractor….For instance, let’s say a child who is instantly relieved of his or her seizure…A common anecdote of a Chiropractor…would you agree that research is warranted? Or would you write it off as coincidence? What if it happened time and time again as it does on a regular basis in Chiropractic offices? Would it be a series of co-incidences and anecdotes or would you then agree that research to the benefits of ADJUSTMENTS (not manipulations) are warranted?
What does that mean to be “instantly relieved” of a seizure? This is an incoherent statement. Seizures are events. They last 1-3 minutes typically, which means they stop spontaneously. So anything you do during a seizure will be followed rapidly by the seizure stopping. Coincidence alone is enough to explain the occasional, even frequent, association between an intervention (like an adjustment) and the end of the seizure. Only statistical information would be able to tell if the seizure duration were actually decreased, since you can’t know how long the seizure would have lasted.
The only exception to the fact that seizures stop on their own is status epilepticus (a continuous seizure) and it is gross malpractice to treat status epilepticus with anything other than accepted emergency protocols.
So the anecdotal observation of seizures stopping is very problematic. If there were any plausibility to such an observation, that might warrant a pilot study – gathering some statistical data – to see if more elaborate research were indicated. But there is no plausibility to a specific effect from a chiropractic adjustment to altering the course of an electrical event in the brain. There may be non-specific effects from generic sensory feedback (depending upon the type of seizure), but even that is highly questionable. In some patients stimulating part of the brain may prevent the spread of a focal seizure (a seizure that is occurring in just part of the brain, not the whole brain), but it does not stop the seizure instantly. It is also highly unlikely that an adjustment would provide the specific type of brain activation that would have this effect.
It should also be noted that not everything that shakes is a seizure. One hallmark of a seizure is that it cannot be stopped by interacting with the patient, and this is often done to help distinguish a true seizure from a non-epileptic mimicker.
Further, there are no controlled studies supporting the use of chiropractic to treat epilepsy (reduce the frequency of seizures) or to treat seizures in progress. There are only case reports and aggregates of those case reports. Chiropractors have made no progress in research – they have not explored any plausible mechanism, and they have not established that there is a real effect. They are stuck in the starting box – presenting anecdotes. They claim that this justifies further research, but then never do that research. Rather, they use anecdotes to justify treatment, which is completely inappropriate, even unethical.
Imagine if a pharmaceutical company tried to market a drug for seizures and offered as supporting evidence only uncontrolled anecdotes. Imagine further that they dismissed reported cases of liver failure occurring after taking their drug as coincidence.
Next we are given anecdotes about asthma:
I myself was a medical “failure.” As a teen, I was diagnosed with “Asthma” and was told there is no cure, but it can be controlled and treated with medication. That was a risk/benefit decision that I choose to take, although against my judgment. After multiple years of medication, I found a Chiropractor who adjusted my neck subluxations and my asthma went away; I threw away my medications and haven’t looked back since. The only change I made was to be adjusted. Even today, in our Chiropractic office, people with “asthma” find they no longer need their medications, breathe easier and enjoy life to the fullest potential they dream of. Doesn’t that warrant further investigation?
The exact same criticisms apply – there is no plausible mechanism, and all we have are anecdotes. Also, asthma attacks, like seizures, are unpredictable events and are subject to a host of psychological and lifestyle factors. This means they are very susceptible to false-positive observations – it is easy to think there is an effect from an intervention when there isn’t.
In the case of asthma, however, we actually do have some clinical trials. A recent Cochrane systematic review (which I should note does not factor in the lack of plausibility) of manual therapy for asthma concluded:
“There is insufficient evidence to support the use of manual therapies for patients with asthma.”
Another review in the Annals of Allergy Asthma and Immunology from 2004 concluded:
“There is currently no evidence to support the use of chiropractic SMT as a primary treatment for asthma or allergy”
Perhaps the single best designed study of chiropractic and asthma was published in 1998 in the NEJM -A comparison of active and simulated chiropractic manipulation as adjunctive treatment for childhood asthma. This study was well-designed and was a collaboration among chiropractors and MDs. The results were dead negative:
In children with mild or moderate asthma, the addition of chiropractic spinal manipulation to usual medical care provided no benefit.
Of course, after the results were in chiropractors complained, and of course no study is perfect so there were nits to pick. But this study represents the best evidence to date – and don’t forget the recent systematic reviews that also show no evidence. If this were a mainstream medical intervention, it would be dead in the water. If proponents of the treatment did not want to give up, then the onus would be on them to design better and more definitive studies and show a real effect, or admit defeat and move on.
Chiropractors did what non-science-based practitioners do – they complained but then never did the follow up studies. Instead they went backwards, doing pilot studies and case reports. The high quality evidence was against them, so they went back to low quality evidence where false-positives are common. What they did not do was stop promoting adjustments for asthma – the one adjustment they did not make was adjusting their practice to the best scientific evidence.
Instead we get the endless cycle of anecdotes and cries for more research, all the while practice continues without change. Again – imagine a pharmaceutical company doing this.
Cause and Effect next writes:
Secondly, it is the treatment that is of concern to the Chiropractor, as we do not “treat.” For example, Hypertension…a typical medical scientific approach is to administer a medication to lower blood pressure….at least that is what my patients and friendly MDs tell me…but why? To lower the “number?” Why not then lower the BP when a person is exercising? The body has driven it up to accommodate the need of increased blood flow (due to exercise); but it is now “not normal” according to medical standards; it is above “normal.” Hypertension is the same…the body reacting to an increase in “exercise;” a situation that requires increased blood flow.
This is a juicy straw man – attacking a childish caricature of modern medicine rather than actual practice. This is not to say that there are no bad doctors out there, of course there are. But they do not represent the standard of care.
In general, good clinical practice includes avoiding the temptation to simply treat numbers. I teach this to medical students all the time – what are you actually treating? Are you just trying to make yourself feel good by making the numbers better, or will this help the patient?
However, with blood pressure, we do treat the number. That is because high blood pressure is the “silent killer” – it usually causes no symptoms but it increases the risk of strokes and heart attacks. This increased risk correlates with the number – so yes, we treat the number as a preventive measure. This is real, effective, preventive medicine based upon rock solid scientific evidence and plausible and well-established mechanisms.
Notice the further silly straw man he includes: “Why not then lower the BP when a person is exercising?” This represents a gross misunderstanding of the standard of care. Hypertension is diagnosed on the basis of chronically increased blood pressure at rest. In fact, the diagnosis of hypertension needs to be confirmed by multiple measures. We even worry that the patient’s blood pressure might be artificially elevated because they are anxious about their doctor visit, so-called “white coat hypertension.” We do not want to treat blood pressure that is physiologically elevated due to normal sympathetic activity, from exercise or even anxiety, only primary hypertension – “primary” means it is not secondary to a normal physiological cause.
Much of the rest of Cause and Effect’s comment has to do with a misunderstanding of risk/benefit analysis. He writes:
When people DIE due to medication, liver damage is due to medication, kidney failure is due to medication…When proper medical protocols are followed and people DIE…when the wrong organ is removed, or the wrong knee is operated on…when does the risk/benefit need to be re-evaluated? The ratios are minimal, yes, but so to are the ratios of Chiropractic and stroke.
The answer is, that risk/benefit ratios are constantly evaluated and re-evaluated in medicine. And (this is an important bit) medical practice actually changes in response to such analysis. For example, felbatol was a new anti-seizure drug that came on the market about a decade ago. It was demonstrated to be safe and effective in large double-blind clinical trials. There was far more evidence for the safety and effectiveness of this drug than for chiropractic neck manipulation for any indication. Once on the market, however, there were reports of a number of cases of liver damage. The FDA says: “THE REPORTED RATE IN THE U.S. HAS BEEN ABOUT 6 CASES OF LIVER FAILURE LEADING TO DEATH OR TRANSPLANT PER 75,000 PATIENT YEARS OF USE.”
This resulted in the immediate suspension of the drug while the data was reviewed. Then the FDA decided that a black-box warning was indicated, with liver monitoring in patients on felbatol. Prescriptions for felbatol plummeted, as the new risk/benefit assessment favored the use of other safer drugs for most patients. I have not seen a patient on this drug in the last 10 years, especially since there are now newer anti-seizure drugs with no reported liver or other organ toxicity.
There were fewer cases of liver failure from this drug than reported cases of stroke following chiropractic neck manipulation, so why hasn’t the chiropractic community responded in a way similar to the medical community? Some chiropractors rail against the risks of mainstream medicine, ignoring the benefits, while they promote treatments without proven benefit and ignore their own risks. They then have the nerve to accuse physicians of applying a double standard.
Another chiropractor, carpdc, writes:
The good neurologists pontificating is one example of the deity complex that has gotten medicine to be so mistrusted by the average consumer today. We are continuing to fund good studies in chiroipractic and I would welcome you to my practice with open arms so that we can come together and do what serves patients best.
The dismissal of legitimate criticism as “pontificating” from a “deity complex” is a classic ad hominem logical fallacy. While referring vaguely to “good studies” carpdc only offers anecdotes to support his practices. He offers to have me visit his practice, so that I can add my own anecdotal observations to the mix – missing the point that my anecdotal observations are no better than anyone else’s. How about some controlled clinical data?
Further, while offering to “come together” he then writes:
Let’s leave medicine to what it can competently treat which is acute trauma and life threatening situations. Medicine must do better though. It is vastly inadequate in answering the rise of degenerative diseases and woefully inadequate in the maintenance of health. This is where chiropractic is FAR superior to allopathy.
He is dismissing all of medicine that does not deal with trauma or acute life-threatening situations, which is most of medicine and just about all of my practice as a neurologist. Of course medicine can and should do better – this will always be the case. But he is implying that our approach to health maintenance is misguided or wrong, which is based upon nothing but propaganda.
He then follows up with the outrageous claim that chiropractic is “FAR” superior to “allopathy.” Allopathy is not a meaningful term. It is a derogatory term invented by Hannheman, the inventor of the fairy tale known as homeopathy, to denigrate the practices of the time. Modern medicine does not have much relationship to what he dismissed as “allopathy.”
Also, I challenge carpdc to provide adequate evidence to show that chiropractic is superior to science-based medicine for anything, let alone far superior for all health maintenance and degenerative diseases.
Given these statements, I can only conclude that carpdc is insincere in his offer to “come together.”
Finally, Nwtk2007 joined the frey with this:
The ratios in chiro are much, much better than in medicine when chiro is appropriate.
The bloggers here only admit to benefit for uncomplicated low back pain but evidence has been posted supporting chiro for neck pain and HA, but they refuse to even read it or consider it, thus they feel there is never a good reason to do cervical manipulation based upon their assessment of the “risk to benefit” ratio.
Again, an unsubstantiated claim for chiropractic superiority, and an unwarranted ad hominem. In fact, I and my colleagues at Science-Based Medicine, as well as many other science bloggers, make a specific effort to read and review published evidence. And again, I have nothing against manipulation as a treatment modality, I just want it to be science-based.
While Nwtk2007 accuses us of refusing to look at evidence, he does not provide anything specific.
But, TheTruth (I admit I always have a negative reaction to anyone attempting to grab the mantle of “Truth”) does offer a specific reference – http://www.webmd.com/hypertension-high-blood-pressure/news/20070316/chiropractic-cuts-blood-pressure.
This is a small (50 subjects) pilot study – even the study authors label it as such in the title. A small pilot study of an implausible treatment is not convincing. This is not a double-standard – I would not be compelled by such evidence for any implausible treatment, and not even for a plausible treatment if that was all there was.
Individual studies, or small numbers of pilot studies, are simply not compelling. Remember the research of John Iaonnidis – he convincingly showed that most published medical studies are later refuted by better studies. Also, the risk of this increases with the implausibility of the treatment.
What science-based practitioners rely upon are studies that are well-designed and reproducible – the kind of studies that eventually evolve out of those pilot studies. Chiropractic has not been able to produce such studies for any of the medical claims made for it. There have been enough studies to show a symptomatic benefit for uncomplicated lower back pain, but no better than other standard treatment modalities.
But for asthma, seizures, blood pressure, headaches – no. Just mixed results from small studies, and chiropractors cherry pick the positive ones.
I think the quality of the arguments put forth by the chiropractors trying to defend their profession speak for themselves. But further, I am struck by the hypocrisy of whining about evidence-based criticisms of chiropractic in the same comments that make outrageous and unsupported attacks on mainstream medicine.
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