Few subjects lead to such heated debate as the risk of stroke after chiropractic manipulations (if you think this is an exaggeration, look at the comment sections of previous posts on this subject). Almost invariably, one comes to the conclusion that more evidence would be helpful for arriving at firmer conclusions. Before this background, this new publication by researchers (mostly chiropractors) from the US ‘Dartmouth Institute for Health Policy & Clinical Practice’ is noteworthy.
The purpose of this study was to quantify the risk of stroke after chiropractic spinal manipulation, as compared to evaluation by a primary care physician, for Medicare beneficiaries aged 66 to 99 years with neck pain.
The researchers conducted a retrospective cohort analysis of a 100% sample of annualized Medicare claims data on 1 157 475 beneficiaries aged 66 to 99 years with an office visit to either a chiropractor or to a primary care physician for neck pain. They compared hazard of vertebrobasilar stroke and any stroke at 7 and 30 days after office visit using a Cox proportional hazards model. We used direct adjusted survival curves to estimate cumulative probability of stroke up to 30 days for the 2 cohorts.
The findings indicate that the proportion of subjects with a stroke of any type in the chiropractic cohort was 1.2 per 1000 at 7 days and 5.1 per 1000 at 30 days. In the primary care cohort, the proportion of subjects with a stroke of any type was 1.4 per 1000 at 7 days and 2.8 per 1000 at 30 days. In the chiropractic cohort, the adjusted risk of stroke was significantly lower at 7 days as compared to the primary care cohort (hazard ratio, 0.39; 95% confidence interval, 0.33-0.45), but at 30 days, a slight elevation in risk was observed for the chiropractic cohort (hazard ratio, 1.10; 95% confidence interval, 1.01-1.19).
The authors conclude that, among Medicare B beneficiaries aged 66 to 99 years with neck pain, incidence of vertebrobasilar stroke was extremely low. Small differences in risk between patients who saw a chiropractor and those who saw a primary care physician are probably not clinically significant.
I do, of course, applaud any new evidence on this rather ‘hot’ topic – but is it just me, or are the above conclusions a bit odd? Five strokes per 1000 patients is definitely not “extremely low” in my book; and furthermore I do wonder whether all experts would agree that a doubling of risk at 30 days in the chiropractic cohort is “probably not clinically significant” – particularly, if we consider that chiropractic spinal manipulation has so very little proven benefit.
My message to (chiropractic) researchers is simple: PLEASE REMEMBER THAT SCIENCE IS NOT A TOOL FOR CONFIRMING BUT FOR TESTING HYPOTHESES.
On 1/12/2014 I published a post in which I offered to give lectures to students of alternative medicine:
Getting good and experienced lecturers for courses is not easy. Having someone who has done more research than most working in the field and who is internationally known, might therefore be a thrill for students and an image-boosting experience of colleges. In the true Christmas spirit, I am today making the offer of being of assistance to the many struggling educational institutions of alternative medicine .
A few days ago, I tweeted about my willingness to give free lectures to homeopathic colleges (so far without response). Having thought about it a bit, I would now like to extend this offer. I would be happy to give a free lecture to the students of any educational institution of alternative medicine.
I did not think that this would create much interest – and I was right: only the ANGLO-EUROPEAN COLLEGE OF CHIROPRACTIC has so far hoisted me on my own petard and, after some discussion (see comment section of the original post) hosted me for a lecture. Several people seem keen on knowing how this went; so here is a brief report.
I was received, on 14/1/2015, with the utmost kindness by my host David Newell. We has a coffee and a chat and then it was time to start the lecture. The hall was packed with ~150 students and the same number was listening in a second lecture hall to which my talk was being transmitted.
We had agreed on the title CHIROPRACTIC: FALLACIES AND FACTS. So, after telling the audience about my professional background, I elaborated on 7 fallacies:
- Appeal to tradition
- Appeal to authority
- Appeal to popularity
- Subluxation exists
- Spinal manipulation is effective
- Spinal manipulation is safe
- Ad hominem attack
Numbers 3, 5 and 6 were dealt with in more detail than the rest. The organisers had asked me to finish by elaborating on what I perceive as the future challenges of chiropractic; so I did:
- Stop happily promoting bogus treatments
- Denounce obsolete concepts like ‘subluxation’
- Clarify differences between chiros, osteos and physios
- Start a culture of critical thinking
- Take action against charlatans in your ranks
- Stop attacking everyone who voices criticism
I ended by pointing out that the biggest challenge, in my view, was to “demonstrate with rigorous science which chiropractic treatments demonstrably generate more good than harm for which condition”.
We had agreed that my lecture would be followed by half an hour of discussion; this period turned out to be lively and had to be extended to a full hour. Most questions initially came from the tutors rather than the students, and most were polite – I had expected much more aggression.
In his email thanking me for coming to Bournemouth, David Newell wrote about the event: The general feedback from staff and students was one of relief that you possessed only one head, :-). I hope you may have felt the same about us. You came over as someone who had strong views, a fair amount of which we disagreed with, but that presented them in a calm, informative and courteous manner as we did in listening and discussing issues after your talk. I think everyone enjoyed the questions and debate and felt that some of the points you made were indeed fair critique of what the profession may need to do, to secure a more inclusive role in the health care arena.
My own impression of the day is that some of my messages were not really understood, that some of the questions, including some from the tutors, seemed like coming from a different planet, and that people were more out to teach me than to learn from my talk. One overall impression that I took home from that day is that, even in this college which prides itself of being open to scientific evidence and unimpressed by chiropractic fundamentalism, students are strangely different from other health care professionals. The most tangible aspect of this is the openly hostile attitude against drug therapies voiced during the discussion by some students.
The question I always ask myself after having invested a lot of time in preparing and delivering a lecture is: WAS IT WORTH IT? In the case of this lecture, I think the answer is YES. With 300 students present, I am fairly confident that I did manage to stimulate a tiny bit of critical thinking in a tiny percentage of them. The chiropractic profession needs this badly!
Few subjects make chiropractors more uneasy than a discussion of the safety of their spinal manipulations. Many chiropractors flatly deny that there are any risks at all. However, the evidence seems to tell a different story.
The purpose of a new review was to summarise the literature for cases of adverse events in infants and children treated by chiropractors or other manual therapists, identifying treatment type and if a preexisting pathology was present. English language, peer-reviewed journals and non-peer-reviewed case reports discussing adverse events (ranging from minor to serious) were systematically searched from inception of the relevant searchable bibliographic databases through March 2014. Articles not referring to infants or children were excluded.
Thirty-one articles met the selection criteria. A total of 12 articles reporting 15 serious adverse events were found. Three deaths occurred under the care of various providers (1 physical therapist, 1 unknown practitioner, and 1 craniosacral therapist) and 12 serious injuries were reported (7 chiropractors/doctors of chiropractic, 1 medical practitioner, 1 osteopath, 2 physical therapists, and 1 unknown practitioner). High-velocity, extension, and rotational spinal manipulation was reported in most cases, with 1 case involving forcibly applied craniosacral dural tension and another involving use of an adjusting instrument. Underlying preexisting pathology was identified in a majority of the cases.
The authors concluded that published cases of serious adverse events in infants and children receiving chiropractic, osteopathic, physiotherapy, or manual medical therapy are rare. The 3 deaths that have been reported were associated with various manual therapists; however, no deaths associated with chiropractic care were found in the literature to date. Because underlying preexisting pathology was associated in a majority of reported cases, performing a thorough history and examination to exclude anatomical or neurologic anomalies before applying any manual therapy may further reduce adverse events across all manual therapy professions.
This review is a valuable addition to our knowledge about the risks of spinal manipulations. My own review summarised 26 deaths after chiropractic manipulations. In several of these instances, the age of the patient had not been reported. Therefore the above conclusion (no deaths associated with chiropractic) seems a little odd.
The following text is a shortened version of the discussion of my review which, I think, addresses most of the pertinent issues.
… numerous deaths have been associated with chiropractic. Usually high-velocity, short-lever thrusts of the upper spine with rotation are implicated. They are believed to cause vertebral arterial dissection in predisposed individuals which, in turn, can lead to a chain of events including stroke and death. Many chiropractors claim that, because arterial dissection can also occur spontaneously, causality between the chiropractic intervention and arterial dissection is not proven. However, when carefully evaluating the known facts, one does arrive at the conclusion that causality is at least likely. Even if it were merely a remote possibility, the precautionary principle in healthcare would mean that neck manipulations should be considered unsafe until proven otherwise. Moreover, there is no good evidence for assuming that neck manipulation is an effective therapy for any medical condition. Thus, the risk-benefit balance for chiropractic neck manipulation fails to be positive.
Reliable estimates of the frequency of vascular accidents are prevented by the fact that underreporting is known to be substantial. In a survey of UK neurologists, for instance, under-reporting of serious complications was 100%. Those cases which are published often turn out to be incomplete. Of 40 case reports of serious adverse effects associated with spinal manipulation, nine failed to provide any information about the clinical outcome. Incomplete reporting of outcomes might therefore further increase the true number of fatalities.
This review is focussed on deaths after chiropractic, yet neck manipulations are, of course, used by other healthcare professionals as well. The reason for this focus is simple: chiropractors are more frequently associated with serious manipulation-related adverse effects than osteopaths, physiotherapists, doctors or other professionals. Of the 40 cases of serious adverse effects mentioned above, 28 can be traced back to a chiropractor and none to a osteopath. A review of complications after spinal manipulations by any type of healthcare professional included three deaths related to osteopaths, nine to medical practitioners, none to a physiotherapist, one to a naturopath and 17 to chiropractors. This article also summarised a total of 265 vascular accidents of which 142 were linked to chiropractors. Another review of complications after neck manipulations published by 1997 included 177 vascular accidents, 32 of which were fatal. The vast majority of these cases were associated with chiropractic and none with physiotherapy. The most obvious explanation for the dominance of chiropractic is that chiropractors routinely employ high-velocity, short-lever thrusts on the upper spine with a rotational element, while the other healthcare professionals use them much more sparingly.[REFERENCES FOR THE ABOVE STATEMENTS CAN BE FOUND IN MY REVIEW]
Even though I have not yet posted a single article on this subject, it already proved to be a most controversial subject in the comments section. A new analysis of the evidence has just been published, and, in view of the news just out of a Royal Charter for the UK College of Chiropractors, it is time to dedicate some real attention to this important issue.
The analysis comes in the form of a systematic review authored by an international team of chiropractors (we should not fear therefore that the authors have an “anti-chiro bias”). Their declared aim was “to determine whether conclusive evidence of a strong association [between neck manipulation and vascular accidents] exists”. The authors make it clear that they only considered case-control studies and omitted all other articles.
They found 4 such publications all of which had methodological limitations. Two studies were of acceptable quality, and one of these studies seemed to show an association between neck manipulation and stroke, while the other one did not. The authors’ conclusion is ambivalent: “Conclusive evidence is lacking for a strong association between neck manipulation and stroke, but it is also lacking for no association”.
The 4 case-control studies, their strength and weaknesses are, of course, well-known and have been discussed several times before. It was also known that the totality of these data fail to provide a clear picture. I would therefore argue that, in such a situation, we need to include further evidence in an attempt to advance the discussion.
Generally speaking, whenever we assess therapeutic safety, we must not ignore case-reports. One might be next to meaningless but collectively they can provide strong indicators of risk. In drug research, for instance, they send invaluable signals about potential problems and many drugs have been withdrawn from the market purely on the basis of case-reports. If we include case-reports in an analysis of the risks of neck manipulations, the evidence generated by the existing case-control studies appears in a very different light. There are virtually hundreds of cases where neck manipulations have seriously injured patients, and many have suffered permanent neurological deficits or worse. Whenever causation is validated by experts who are not chiropractors and thus not burdened with a professional bias, investigators find that most of the criteria for a causal relationship are fulfilled.
While the omission of case-reports in the new review is regrettable, I find many of the staements of the authors helpful and commendable, particularly considering that they are chiropractors. They seem to be aware that, when there is genuine uncertainty, we ought to err on the safe side [the precautionary principle]. Crucially, they comment on the practical implications of our existing knowledge: “Considering this uncertainty, informed consent is warranted for cervical spinal manipulative therapy that advises patients of a possible increase in the risk of a rare form of stroke…” A little later, in their discussion they write: “As the possibility of an association between cervical spinal manipulative therapy and vascular accidents cannot be ruled out, practitioners of cervical spinal manipulative therapy are obliged to take all reasonable steps that aim to minimise the potential risk of stroke. There is evidence that cervical rotation places greater stresses on vertebral arteries than other movements such as lateral flexion, and so it would seem wise to avoid techniques that involve full rotation of the head.”
At this point it is, I think, important to note that UK chiropractors tend not to obtain informed consent from their patients. This is, of course, a grave breach of medical ethics. It becomes even graver, when we consider that the GCC seems to do nothing about it, even though it has been known for many years.
Is this profession really worthy of a Royal Charter? This and the other question raised here require some serious consideration and discussion which, no doubt, will follow this short post.