I recently came across this article; essentially it claims that, in 1918, chiropractic proved itself to be the method of choice for treating the flu!
Here is a short quote from it:
Chiropractors got fantastic results from influenza patients while those under medical care died like flies all around. Statistics reflect a most amazing, almost miraculous state of affairs. The medical profession was practically helpless with the flu victims but chiropractors seemed able to do no wrong.”
“In Davenport, Iowa, 50 medical doctors treated 4,953 cases, with 274 deaths. In the same city, 150 chiropractors including students and faculty of the Palmer School of Chiropractic, treated 1,635 cases with only one death.”
“In the state of Iowa, medical doctors treated 93,590 patients, with 6,116 deaths – a loss of one patient out of every 15. In the same state, excluding Davenport, 4,735 patients were treated by chiropractors with a loss of only 6 cases – a loss of one patient out of every 789.
“National figures show that 1,142 chiropractors treated 46,394 patients for influenza during 1918, with a loss of 54 patients – one out of every 886.”
“Reports show that in New York City, during the influenza epidemic of 1918, out of every 10,000 cases medically treated, 950 died; and in every 10,000 pneumonia cases medically treated 6,400 died. These figures are exact, for in that city these are reportable diseases.”
“In the same epidemic, under drugless methods, only 25 patients died of influenza out of every 10,000 cases; and only 100 patients died of pneumonia out of every 10,000 cases…”
“In the same epidemic reports show that chiropractors in Oklahoma treated 3,490 cases of influenza with only 7 deaths. But the best part of this is, in Oklahoma there is a clear record showing that chiropractors were called in 233 cases where medical doctors had cared for the patients, and finally gave them up as lost. The chiropractors saved all these lost cases but 25.”
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So what does that sort of ‘evidence’ really show?
Does it prove that chiropractic is effective against influenza?
Does it even suggest that chiropractic is effective against influenza?
I think it shows that some chiropractors (like many homeopaths) are deluded to a point where they are unable to differentiate pseudoscience from science, anecdote from evidence, cause from effect, etc.
In the case you need more explanations, let me re-phrase this section from a previous post:
In the typical epidemiological case/control study, one large group of patients [A] is retrospectively compared to another group [B]. By large, I mean with a sample size of thousands of patients. In our case, group A has been treated by chiropractors, while group B received the treatments available at the time. It is true that several of such reports seemed to suggest that chiropractic works. But this does by no means prove anything; the result might have been due to a range of circumstances, for instance:
- group A might have been less ill than group B,
- group A might have been richer and therefore better nourished,
- group A might have benefitted from better hygiene,
- group A might have received better care, e. g. hydration,
- group B might have received treatments that made the situation not better but worse.
Because these are RETROSPECTIVE studies, there is no way to account for these and many other factors that might have influenced the outcome. This means that epidemiological studies of this nature can generate interesting results which, in turn, need testing in properly controlled studies where these confounding factors are adequately controlled for. Without such tests, they are next to worthless.
How often have we heard that chiropractic has moved on and has given up the concept of subluxation/malalignment? For sure there is no evidence for such nonsense, and it would be high time to give it up! But, as has been argued here and elsewhere, if chiros give it up, what is there left? What then would differentiate them from physios ? The answer is not a lot.
In any case, chiros have by no means given up subluxation. One can argue this point ad nauseam; yet, most chiros remain in denial.
For this post, I have chosen a different approach to make my point. I simply went on twitter and had a look what messages chiros tweet. The impression I got is that the majority of chiros are totally immersed in subluxation. To provide some proof, I have copied a few images – if chiros do not listen to words, perhaps they understand pictures, I thought.
So, here we go – enjoy![please click to see them full size]
On this blog, we have often discussed the risks of spinal manipulation. As I see it, the information we have at present suggests that
- mild to moderate adverse effects are extremely frequent and occur in about half of all patients;
- serious adverse effects are being reported regularly;
- the occur usually with chiropractic manipulations of the neck (which are not of proven efficacy for any condition) and often relate to vascular accidents;
- the consequences can be permanent neurological deficits and even deaths;
- under-reporting of such cases might be considerable and therefore precise incidence figures are not available;
- there is no system to accurately monitor the risks;
- chiropractors are in denial of these problems.
Considering the seriousness of these issues, it is important to do more rigorous research. Therefore, any new paper published on this subject is welcome. A recent article might shed new light on the topic.
The objective of this systematic review was to identify characteristics of 1) patients, 2) practitioners, 3) treatment process and 4) adverse events (AE) occurring after cervical spinal manipulation (CSM) or cervical mobilization. A systematic searches were performed in 6 electronic databases up to December 2014. Of the initial 1043 articles thus located, 144 were included, containing 227 cases. 117 cases described male patients with a mean age of 45 and a mean age of 39 for females. Most patients were treated by chiropractors (66%). Manipulation was reported in 95% of the cases, and neck pain was the most frequent indication for the treatment. Cervical arterial dissection (CAD) was reported in 57% of the cases and 45.8% had immediate onset symptoms. The overall distribution of gender for CAD was 55% for female. Patient characteristics were described poorly. No clear patient profile, related to the risk of AE after CSM, could be extracted, except that women seemed more at risk for CAD. The authors of this review concluded that there seems to be under-reporting of cases. Further research should focus on a more uniform and complete registration of AE using standardized terminology.
This article provides little new information; but it does confirm what I have been saying since many years: NECK MANIPULATIONS ARE ASSOCIATED WITH SERIOUS RISKS AND SHOULD THEREFORE BE AVOIDED.
Systematic reviews are aimed at summarising and critically evaluating the evidence on a specific research question. They are the highest level of evidence and are more reliable than anything else we have. Therefore, they represent a most useful tool for both clinicians and researchers.
But there are, of course, exceptions. Take, for instance, this recent systematic review by researchers from the
- Texas Chiropractic College, Pasadena, the Palmer Center for Chiropractic Research, Palmer College of Chiropractic, Davenport,
- Department of Planning, Policy and Design, University of California, Irvine,
- VA Puget Sound Health Care System, Tacoma,
- New York Chiropractic College, Seneca Falls,
- Logan University College of Chiropractic, Chesterfield,
- University of Western States, Portland.
How often have I pointed out that most studies of chiropractic (and other alternative therapies) are overtly unethical because they fail to report adverse events? And if you think this is merely my opinion, you are mistaken. This new analysis by a team of chiropractors aimed to describe the extent of adverse events reporting in published RCTs of Spinal Manipulative Therapy (SMT), and to determine whether the quality of reporting has improved since publication of the 2010 Consolidated Standards Of Reporting Trials (CONSORT) statement.
The Physiotherapy Evidence Database and the Cochrane Central Register of Controlled Trials were searched for RCTs involving SMT. Domains of interest included classifications of adverse events, completeness of adverse events reporting, nomenclature used to describe the events, methodological quality of the study, and details of the publishing journal. Data were analysed using descriptive statistics. Frequencies and proportions of trials reporting on each of the specified domains above were calculated. Differences in proportions between pre- and post-CONSORT trials were calculated with 95% confidence intervals using standard methods, and statistical comparisons were analysed using tests for equality of proportions with continuity correction.
Of 7,398 records identified in the electronic searches, 368 articles were eligible for inclusion in this review. Adverse events were reported in 140 (38.0%) articles. There was a significant increase in the reporting of adverse events post-CONSORT (p=.001). There were two major adverse events reported (0.3%). Only 22 articles (15.7%) reported on adverse events in the abstract. There were no differences in reporting of adverse events post-CONSORT for any of the chosen parameters.
The authors concluded that although there has been an increase in reporting adverse events since the introduction of the 2010 CONSORT guidelines, the current level should be seen as inadequate and unacceptable. We recommend that authors adhere to the CONSORT statement when reporting adverse events associated with RCTs that involve SMT.
We conducted a very similar analysis back in 2012. Specifically, we evaluated all 60 RCTs of chiropractic SMT published between 2000 and 2011 and found that 29 of them did not mention adverse effects at all. Sixteen RCTs reported that no adverse effects had occurred (which I find hard to believe since reliable data show that about 50% of patients experience adverse effects after consulting a chiropractor). Complete information on incidence, severity, duration, frequency and method of reporting of adverse effects was included in only one RCT. Conflicts of interests were not mentioned by the majority of authors. Our conclusion was that adverse effects are poorly reported in recent RCTs of chiropractic manipulations.
The new paper suggests that the situation has improved a little, yet it is still wholly unacceptable. To conduct a clinical trial and fail to mention adverse effects is not, as the authors of the new article suggest, against current guidelines; it is a clear and flagrant violation of medical ethics. I blame the authors of such papers, the reviewers and the journal editors for behaving dishonourably and urge them to get their act together.
The effects of such non-reporting are obvious: anyone looking at the evidence (for instance via systematic reviews) will get a false-positive impression of the safety of SMT. Consequently, chiropractors are able to claim that very few adverse effects have been reported in the literature, therefore our hallmark therapy SMT is demonstrably safe. Those who claim otherwise are quite simply alarmist.
The new guidelines by the American College of Physicians entitled ‘Noninvasive Treatments for Acute, Subacute, and Chronic Low Back Pain: A Clinical Practice Guideline From the American College of Physicians’ have already been the subject of the previous post. Today, I want to have a closer look at a small section of these guidelines which, I think, is crucial. It is entitled ‘HARMS OF NONPHARMACOLOGIC THERAPIES’. I have taken the liberty of copying it below:
“Evidence on adverse events from the included RCTs and systematic reviews was limited, and the quality of evidence for all available harms data is low. Harms were poorly reported (if they were reported at all) for most of the interventions.
Low-quality evidence showed no reported harms or serious adverse events associated with tai chi, psychological interventions, multidisciplinary rehabilitation, ultrasound, acupuncture, lumbar support, or traction (9,95,150,170–174). Low-quality evidence showed that when harms were reported for exercise, they were often related to muscle soreness and increased pain, and no serious harms were reported. All reported harms associated with yoga were mild to moderate (119). Low-quality evidence showed that none of the RCTs reported any serious adverse events with massage, although 2 RCTs reported soreness during or after massage therapy (175,176). Adverse events associated with spinal manipulation included muscle soreness or transient increases in pain (134). There were few adverse events reported and no clear differences between MCE and controls. Transcutaneous electrical nerve stimulation was associated with an increased risk for skin site reaction but not serious adverse events (177). Two RCTs (178,179) showed an increased risk for skin flushing with heat compared with no heat or placebo, and no serious adverse events were reported. There were no data on cold therapy. Evidence was insufficient to determine harms of electrical muscle stimulation, LLLT, percutaneous electrical nerve stimulation, interferential therapy, short-wave diathermy, and taping.”
The first thing that strikes me is the brevity of the section. Surely, guidelines of this nature must include a full discussion of the risks of the treatments in question!
The second thing that is noteworthy is the fact that the authors confirm the fact I have been banging on about for years: clinical trials of alternative therapies far too often fail to mention adverse effects. I have often pointed out that the failure to report adverse effects in clinical trials is an unacceptable violation of medical ethics. By contrast, the guideline authors seem not to feel strongly about this omission.
The third thing that is noteworthy is that the guidelines evaluate the harms of the treatments purely on the basis of the adverse effects reported in the clinical trials and systematic reviews included in their efficacy assessments. This is nonsensical for at least two reasons:
- The guideline authors themselves are aware that the trials very often fail to mention adverse effects.
- For any assessment of harm, one has to go far beyond the evidence of clinical trials, because trials tend to be too small to pick up rare adverse effects, and because they are always conducted under optimally controlled conditions where adverse effects are less likely to occur than in real life.
Together, these features of the assessment of harms explain why the guideline authors arrive at conclusions which are oddly misguided; I would even feel that they resemble a white-wash. Here are two of the most overt misjudgements:
- no harms associated with acupuncture,
- only trivial harm associated with spinal manipulations.
The best evidence we have today shows that acupuncture leads to mild adverse effects in about 10% of all cases and is also associated with very severe complications (e.g. pneumothorax, cardiac tamponade, infections, deaths) in an unknown number of patients. More details can be found for instance here, here, here and here.
And the best evidence available shows that spinal manipulation leads to moderately severe adverse effects in ~50% of all cases. In addition, we know of hundreds of cases of very severe complications resulting in stroke, permanent neurological deficits or deaths. More details can be found for instance here, here, here and here.
In the introduction, I stated that this small section of the guidelines is crucial.
The reason is simple: any responsible therapeutic decision has to be based not just on the efficacy of the treatment in question but on its risk/benefit balance. The evidence shows that the risks of some alternative therapies can be considerable, a fact that is almost totally neglected in the guidelines. Therefore, the recommendations of the new guidelines by the American College of Physicians entitled ‘Noninvasive Treatments for Acute, Subacute, and Chronic Low Back Pain: A Clinical Practice Guideline From the American College of Physicians’ are in several aspects not entirely correct and need to be reconsidered.
The question whether spinal manipulative therapy (SMT) is effective for acute low back pain is still discussed controversially. Chiropractors (they use SMT more regularly than other professionals) try everything to make us believe it does work, while the evidence is far less certain. Therefore, it is worth considering the best and most up-to-date data.
The aim of this paper was to systematically review studies of the effectiveness and harms of SMT for acute (≤6 weeks) low back pain. The research question was straight forward: Is the use of SMT in the management of acute (≤6 weeks) low back pain associated with improvements in pain or function?
A through literature search was conducted to locate all relevant papers. Study quality was assessed using the Cochrane Back and Neck (CBN) Risk of Bias tool. The evidence was assessed using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) criteria. The main outcome measures were pain (measured by either the 100-mm visual analog scale, 11-point numeric rating scale, or other numeric pain scale), function (measured by the 24-point Roland Morris Disability Questionnaire or Oswestry Disability Index [range, 0-100]), or any harms measured within 6 weeks.
Of 26 eligible RCTs identified, 15 RCTs (1711 patients) provided moderate-quality evidence that SMT has a statistically significant association with improvements in pain (pooled mean improvement in the 100-mm visual analog pain scale, −9.95 [95% CI, −15.6 to −4.3]). Twelve RCTs (1381 patients) produced moderate-quality evidence that SMT has a statistically significant association with improvements in function (pooled mean effect size, −0.39 [95% CI, −0.71 to −0.07]). Heterogeneity was not explained by type of clinician performing SMT, type of manipulation, study quality, or whether SMT was given alone or as part of a package of therapies. No RCT reported any serious adverse event. Minor transient adverse events such as increased pain, muscle stiffness, and headache were reported 50% to 67% of the time in large case series of patients treated with SMT.
The authors concluded that among patients with acute low back pain, spinal manipulative therapy was associated with modest improvements in pain and function at up to 6 weeks, with transient minor musculoskeletal harms. However, heterogeneity in study results was large.
This meta-analysis has been celebrated by chiropractors around the world as a triumph for their hallmark therapy, SMT. But there have also been more cautionary voices – not least from the lead author of the paper. Patients undergoing spinal manipulation experienced a decline of 1 point in their pain rating, says Dr. Paul Shekelle, an internist with the West Los Angeles Veterans Affairs Medical Center and the Rand Corporation who headed the study. That’s about the same amount of pain relief as from NSAIDs, over-the-counter nonsteroidal anti-inflammatory medication, such as ibuprofen. The study also found spinal manipulation modestly improved function. On average, patients reported greater ease and comfort engaging in two day-to-day activities — such as finding they could walk more quickly, were having less difficulty turning over in bed or were sleeping more soundly.
It’s not clear exactly how spinal manipulation relieves back pain. But it may reposition the small joints in the spine in a way that causes less pain, according to Dr. Richard Deyo, an internist and professor of evidence-based medicine at the Oregon Health and Science University. Deyo wrote an editorial published along with the study. Another possibility, Deyo says, is that spinal manipulation may restore some material in the disk between the vertebrae, or it may simply relax muscles, which could be important. There may also be mind-body interaction that comes from the “laying of hands” or a trusting relationship between patients and their health care provider, he says.
Deyo notes that there are many possible treatments for lower back pain, including oral medicine, injected medicine, corsets, traction, surgery, acupuncture and massage therapy. But of about 200 treatment options, “no single treatment is clearly superior,” he says.
In another comment by Paul Ingraham the critical tone was much clearer: “Claiming it as a victory is one of the best examples I’ve ever seen of making lemonade out of science lemons! But I can understand the mistake, because the review itself does seem positive at first glance: the benefits of SMT are disingenuously summarized as “statistically significant” in the abstract, with no mention of clinical significance (effect size; see Statistical Significance Abuse). So the abstract sounds like good news to anyone but the most wary readers, while deep in the main text the same results are eventually conceded to be “clinically modest.” But even even that seems excessively generous: personally, I need at least a 2-point improvement in pain on a scale of 10 to consider it a “modest” improvement! This is not a clearly positive review: it shows weak evidence of minor efficacy, based on “significant unexplained heterogeneity” in the results. That is, the results were all over the place — but without any impressive benefits reported by any study — and the mixture can’t be explained by any obvious, measurable factor. This probably means there’s just a lot of noise in the data, too many things that are at least as influential as the treatment itself. Or — more optimistically — it could mean that SMT is “just” disappointingly mediocre on average, but might have more potent benefits in a minority of cases (that no one seems to be able to reliably identify). Far from being good news, this review continues a strong trend (eg Rubinstein 2012) of damning SMT with faint praise, and also adds evidence of backfiring to mix. Although fortunately “no RCT reported any serious adverse event,” it seems that minor harms were legion: “increased pain, muscle stiffness, and headache were reported 50% to 67% of the time in large case series of patients treated with SMT.” That’s a lot of undesirable outcomes. So the average patient has a roughly fifty-fifty chance of up to roughly maybe a 20% improvement… or feeling worse to some unknown degree! That does not sound like a good deal to me. It certainly doesn’t sound like good medicine.”
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As I have made clear in many previous posts, I do fully agree with these latter statements and would add just three points:
- We know that many of the SMT studies completely neglect reporting adverse effects. Therefore it is hardly surprising that no serious complications were on record. Yet, we know that they do occur with sad regularity.
- None of the studies controlled for placebo effects. It is therefore possible – I would say even likely – that a large chunk of the observed benefit is not due to SMT per se but to a placebo response.
- It seems more than questionable whether the benefits of SMT outweigh its risks.
CBC news (Canada) reported yesterday that, more than a decade ago, the Manitoba Chiropractic Health Care Commission had been tasked to review the cost effectiveness of chiropractic services. It therefore prepared a report in 2004 for the Manitoba province and the Manitoba Chiropractors Association. Since then, this report has been kept secret. The report makes 37 recommendations, including:
- Manitoba Health should limit its funding to “chiropractic treatment of acute lower back pain.”
- Manitoba Health should provide “limited coverage of the treatment of neck pain.” The report called the literature around the efficacy of chiropractic care for neck pain “ambiguous or at best weakly supportive” and noted such treatment carried a “not insignificant safety risk.”
- Manitoba Health should not fund chiropractic treatment anyone under 18 “as the literature does not unequivocally justify” the “efficacy or safety” of such treatment.
A Manitoba Ombudsman’s Office report from 2012 might shed some light on why the Manitoba Chiropractic Health Care Commission’s report was never made public. Someone had attempted to get a copy of the report, but large parts of it were redacted. “Access to this record was refused on the basis that disclosure would be harmful to a third party’s business interest,” the ombudsman report notes, “and harm the economic or financial interests or negotiating position of a public body.”
The report also challenged claims that chiropractic treatments can be address a wide variety of medical conditions. It stated that there was not enough evidence to conclude chiropractic treatments are effective in treating muscle tension, migraines, HIV, carpal tunnel syndrome, gastrointestinal problems, infertility or cancer, or as a preventive care treatment. It also said there was not enough evidence to conclude chiropractic treatments are effective for children.
The report urged Manitoba Health to establish a monitoring system to keep a closer eye on “the advertising practices of the Manitoba Chiropractors Association and its members to ensure claims regarding treatments are restricted to those for which proof of efficacy and safety exist.” It suggested the government should have regulatory powers over chiropractic ads.
A recent CBC I-Team investigation found Manitoba chiropractors advertising treatment for a wide range of conditions including Alzheimer’s, autism and pediatric services. The commission report contained sharp criticisms of previous reports that suggested funding chiropractic care could save the health-care system money. Dr. Pranlal Manga authored two widely cited reports which claim that by offering publicly funded chiropractic care, provinces can cut health-care costs. “The Manga study on Manitoba must be rejected as a guide to public policy,” the commission report states, “because its assumptions, methodology and costing of recommendations are all deeply flawed.” The reports states, “What limited evidence the Commission has suggests he [Manga] grossly exaggerates possible medical savings.” Dr. Manga did not respond to CBC’s repeated attempts to contact him.
The commission report also made recommendations around the use of X-ray machines by chiropractors. It suggested chiropractors not own and operate X-ray machines “Given the restrictive conditions under which X-rays are advisable, their poor correlation with low-back problems, their apparent limitation as a guide to appropriate treatment …[and] the apparent complete lack of monitoring [of] the use of X-ray by chiropractors.” Instead, it recommended consulting with radiologists when imaging is deemed necessary. “The Commission is of the view that the public interest, and even chiropractic itself, would be better served if chiropractors had access to radiologists for this service, rather than perform it themselves,” the report said.
All three report authors declined comment. Calls to Dave Chomiak, who was health minister at the time the report was prepared, were not returned. In an email to CBC, Manitoba Chiropractors Association president Perry Taylor said, “I personally have never seen this 13-year-old document and [it] pre-dates my time as President. As such I have no comment on this.” The CBC I-Team offered to go through the report with Taylor but he did not respond.
This report seems to confirm much of what we have discussed repeatedly on this blog: Chiropractic is not nearly as effective and safe as chiropractors try to make us believe. To hide this fact is certainly dishonest and unethical, but it is in some ways understandable: this knowledge would directly threaten the income of most chiropractors.
Yesterday I commented on another post: “the conflict of interest seems obvious: if homeopaths speak the truth, they are out of business. therefore, they are taught untruths from the first day of their training and eventually end up believing them. there is only one solution, as far as I can see: regulators must prevent them from making false claims. if not, this will go on for another 200 years and damage many patients’ health”. In the light of the above report, I will now re-phrase this: the conflict of interest seems obvious: if chiropractors allowed the truth to be known, they would soon be out of business. Therefore, they are taught untruths from the first day of their training and many end up believing them. There is only one solution, as far as I can see: regulators must prevent chiropractors from making false claims. If not, this abuse will go on for another 120 years and damage many patients’ health.
Charlotte Leboeuf-Yde, DC,MPH,PhD, is professor in Clinical Biomechanics at the University of Southern Denmark and works at the French-European Institute of Chiropractic in Paris. She is a chiropractor with extensive research experience, for example, she was one of the first chiropractors to have studied adverse reactions of spinal manipulation.
Charlotte certainly knows a thing or two about adverse effects of spinal manipulation, and I have always found her work interesting. Therefore, I was delighted to find a recent blog post where she discussed the Cassidy study of 2008 and two opposed views on the validity of this much-discussed paper.
One team (Paulus &Thaler) argued, Charlotte explained, that the Cassidy case-control study is faulty, because vertebro-basilar stroke in general was not separated from stroke specifically caused by vertebral artery dissections, the presumed culprit in cervical spinal manipulation. According to Paulus & Thaler, this would potentially result in a dilution of ‘real’ manipulative-related strokes among all other causes of stroke that are much more common. They argue that the Cassidy-analyses therefore were polluted by this misclassification, whereas the other team (Murphy et al) vehemently disagrees.
The final word is clearly not yet pronounced on this issue, Charlotte concluded, and both teams agree that research has to address various methodological challenges to obtain a trustable answer. Nevertheless, without an international collaboration involving prospective cases this seems an almost impossible task, particularly in view of the rarity of the condition; problems in capturing all cases (going from the reversible to the permanent injuries); the likely large anatomical and physiological variations between individuals; and the daunting task of obtaining relevant and precise descriptions of treatments from a multitude of practitioners.
In the meantime, Charlotte concluded, “practitioners and patients have to make a decision, similarly to judging risk in other walks of life, such as, should I take the plane or stay at home?”
I have always thought highly of Charlotte’s work, however, her conclusion made me doubt whether my high opinion of her reasoning was justified.
Should I take the plane or stay at home?
This question is not remotely similar to the question “should I have chiropractic upper neck manipulation or not?”
Here are a the two main reasons why:
- Taking the plane of demonstrably effective in transporting you from A to B, while neck manipulation is not demonstrably effective for anything.
- If you want to go from A to B [assuming B is far way], you need to fly. If you have neck pain or other symptoms, you can employ plenty of therapies other than neck manipulations.
Charlotte Leboeuf-Yde, DC,MPH,PhD, may be a professor in Clinical Biomechanics etc., etc., however, logical and critical thinking do not seem to be her forte.
So, how should we deal with the risks of chiropractic neck manipulations? I think, we should deal with them as responsible healthcare professionals deal with any other suspected therapeutic risks: we must ask whether the known risks of the treatment outweigh the known benefits (as they do with spinal manipulation). If that is so, we have an ethical, legal and moral duty not to employ the therapy in question in routine care. At the same time, we must focus or research efforts on producing full clarity about the open questions. It’s called the precautionary principle!
Is spinal manipulative therapy (SMT) dangerous? This question has kept us on this blog busy for quite some time now. To me, there is little doubt that SMT can cause adverse effects some of which are serious. But many chiropractors seem totally unconvinced. Perhaps this new overview of reviews might help to clarify the issue. Its aim was to elucidate and quantify the risk of serious adverse events (SAEs) associated with SMT.
The authors searched five electronic databases from inception to December 8, 2015 and included reviews on any type of studies, patients, and SMT technique. The primary outcome was SAEs. The quality of the included reviews was assessed using a measurement tool to assess systematic reviews (AMSTAR). Since there were insufficient data for calculating incidence rates of SAEs, they used an alternative approach; the conclusions regarding safety of SMT were extracted for each review, and the communicated opinion were judged by two reviewers independently as safe, harmful, or neutral/unclear. Risk ratios (RRs) of a review communicating that SMT is safe and meeting the requirements for each AMSTAR item, were calculated.
A total of 283 eligible reviews were identified, but only 118 provided data for synthesis. The most frequently described adverse events (AEs) were stroke, headache, and vertebral artery dissection. Fifty-four reviews (46%) expressed that SMT is safe, 15 (13%) expressed that SMT is harmful, and 49 reviews (42%) were neutral or unclear. Thirteen reviews reported incidence estimates for SAEs, roughly ranging from 1 in 20,000 to 1 in 250,000,000 manipulations. Low methodological quality was present, with a median of 4 of 11 AMSTAR items met (interquartile range, 3 to 6). Reviews meeting the requirements for each of the AMSTAR items (i.e. good internal validity) had a higher chance of expressing that SMT is safe.
The authors concluded that it is currently not possible to provide an overall conclusion about the safety of SMT; however, the types of SAEs reported can indeed be significant, sustaining that some risk is present. High quality research and consistent reporting of AEs and SAEs are needed.
This article is valuable, if only for the wealth of information one can extract from it. There are, however, numerous problems. One is that the overview included mostly reviews of the effectiveness of SMT for various conditions. We know that studies of SMT often do not even mention AEs. If such studies are then pooled in a review, they inevitably generate an impression of safety. But this would, of course, be a false-positive result!
The authors of the overview are aware of this problem and address it in the following paragraph: “When only considering the subset of reviews, where the objective was to investigate AEs (37 reviews), then 8 reviews (22%) expressed that SMT is safe, 13 reviews (35%) expressed that SMT is harmful and 16 reviews (43%) were neutral or unclear regarding the safety of SMT. Hence, there is a tendency that a bigger proportion of these reviews are expressing that SMT is harmful compared to the full sample of reviews…”
To my surprise, I found several of my own reviews in the ‘neutral or unclear’ category. Here are the verbatim conclusions of three of them:
- It is concluded that serious cerebrovascular complications of spinal manipulation continue to be reported.
- The most common serious adverse events are vertebrobasilar accidents, disk herniation, and cauda equina syndrome.
- These data indicate that mild and transient adverse events seem to be frequent. Serious adverse events are probably rare but their incidence can only be estimated at present.
I find it puzzling how this could be classified as neutral or unclear. The solution of the puzzle might lie in the methodology used: “we appraised the communicated opinions of each review concerning the safety of SMT based on their conclusions regarding the AEs and SAEs. This was done by two reviewers independently (SMN, LK), who judged the communicated opinions as either ‘safe’, ‘neutral/unclear’ or ‘harmful’, based on the qualitative impression the reviewers had when reading the conclusions. The reviewers had no opinion about the safety/harmfulness of SMT before commencing the judgements. Cohen’s weighted Kappa was calculated for the agreement between the reviewers, with a value of 0.40–0.59 indicating ‘fair agreement’, 0.60–0.74 indicating ‘good agreement’ and ≥0.75 indicating ‘excellent agreement’. Disagreements were resolved by a third reviewer (MH).”
In other words, the categorisation was done on the basis of subjective judgements of two researchers. It seems obvious that, if their attitude was favourable towards SMT, their judgements would be influenced. The three examples from my own work cited above indicates to me that their verdicts were indeed far from objective.
So what is the main message here? In my view, it can be summarized in the following quote from the overview: “a bigger proportion of these reviews are expressing that SMT is harmful …”
Yes, yes, yes – I know that, if you are a chiropractor (or other practitioner using mostly SMT), you are unlikely to agree with this!
Perhaps you can agree with this statement then:
As long as there is reasonable doubt about the safety of SMT, and as long as we cannot be sure that SMT generates more good than harm, we should be very cautious using it for routine healthcare and do rigorous research to determine the truth (it’s called the precautionary principle and applies to all types of healthcare).