I am sure, we have all heard it hundreds of times: THERE ARE IMPORTANT LINKS BETWEEN OUR DIET AND CERTAIN CANCERS. The evidence for this statement seems fairly compelling. Yet it also is complex and often confusing.
A recent review, for instance, suggested that fruits (particularly citrus) and vegetable consumption may be beneficial in the primary prevention of pancreatic cancer, the consumption of whole grains has been shown to reduce the risk and fortification of whole grains with folate may confer further protection. Red meat, cooked at high temperatures, should be avoided, and replaced with poultry or fish. Total fat should be reduced. The use of curcumin and other flavonoids should be encouraged in the diet. Another equally recent review, however, indicated that there is no conclusive evidence as an independent risk factor for isolated nutrients versus adoption of dietary patterns for cancer risk. Cancer colon risk derived from meat intake is influenced by both total intake and its frequency. The interaction of phenolic compounds on metabolic and signalling pathways seems to exert an inhibitory effect on cell proliferation and tumor metastasis and induces apoptosis in various types of cancer cells, including colon, lung, prostate, hepatocellular or breast cancer. A third recent review concluded that cruciferous vegetable intake protects against cancer of the colon, while a forth review suggested that the Mediterranean dietary pattern and diets composed largely of vegetables, fruit, fish, and soy are associated with a decreased risk of breast cancer. There was no evidence of an association between traditional dietary patterns and risk of breast cancer.
Not least based on these mixed messages from the scientific literature, an entire industry has developed selling uncounted alternative cancer-diets and dietary supplements to desperate patients and consumers. They promise much more than just cancer prevention, in fact, leave little doubt about the notion that cancer might be curable by diet. Here are just a few quotes from the thousands of websites promoting alternative cancer diets:
- The Ketogenic Diet is believed capable of starving cancer cells to death, and thus capable of restricting tumour development.
- a more alkaline body makes it difficult for tumors to grow.
- Budwig diet: This diet was developed by Dr. Johanna Budwig who was nominated for the noble Prize sixth times. The diet is intended as a preventative as well as an alternative cancer treatment.
- the Gerson Therapy naturally reactivates your body’s magnificent ability to heal itself – with no damaging side effects. This a powerful, natural treatment boosts the body’s own immune system to heal cancer, arthritis, heart disease, allergies, and many other degenerative diseases. Dr. Max Gerson developed the Gerson Therapy in the 1930s, initially as a treatment for his own debilitating migraines, and eventually as a treatment for degenerative diseases such as skin tuberculosis, diabetes and, most famously, cancer.
- the concept of macrobiotics is much more than an alternative diet for cancer, or any other illness, but rather the ancient Chinese belief that all life, indeed the whole universe, is a balance of two opposing forces Yin and Yang.
Confused? Yes, I do worry how many cancer patients listen to these claims and pin their hopes on one of these diets. But what exactly does the evidence tell us about them?
A German team of researchers evaluated the following alternative cancer-diets: raw vegetables and fruits, alkaline diet, macrobiotics, Gerson’s regime, Budwig’s and low carbohydrate or ketogenic diet. Their extensive searches of the published literature failed to find clinical evidence supporting any of the diets. Furthermore, case reports and pre-clinical data pointed to the potential harm of some of these diets. The authors concluded that considering the lack of evidence of benefits from cancer diets and potential harm by malnutrition, oncologists should engage more in counselling cancer patients on such diets.
In other words, alternative cancer diets – and I mean not just the ones mentioned above, but all of them – are not supported by good evidence for efficacy as a treatment or prevention of any type of cancer. In addition, they might also cause harm.
What follows is obvious: cancer patients should take sound nutritional advice and adopt a healthy general life-style. But they should run a mile as soon as anyone suggests an alternative dietary cure for their disease.
Web-sites have become a leading source of information on health matters. This is particularly true in the realm of alternative medicine. Conventional health care professionals often know too little about this subject to advise their patients, and alternative practitioners are usually too biased to be trusted. So many consumers turn to the Internet and hope that it offers information which is reliable. But is it?
American pharmacists published a study evaluating the quality of on-line information on herbal supplements. They conducted a search of 13 common herbals – including black cohosh, echinacea, garlic, ginkgo, ginseng, green tea, kava, saw palmetto, and St John’s wort - and reviewed the top 50 Web sites for each using a Google search. Subsequently, they analysed clinical claims, warnings, and other safety information.
A total of 1179 Web sites were examined in this way. Less than 8% of retail sites provided information regarding potential adverse effects, drug interactions, and other safety information; only 10.5% recommended consultation with a healthcare professional. Less than 3% cited scientific literature to support their claims.
The authors’ conclusions were worrying: Key safety information is still lacking from many online sources of herbal information. Certain nonretail site types may be more reliable, but physicians and other healthcare professionals should be aware of the variable quality of these sites to help patients make more informed decisions.
Having conducted my fair share of similar research (e.g. here or here or here or here), I can only concur with these conclusions. When it comes to health care, the Internet is a scary place! In the realm of alternative medicine, it is dominated by people who seem not to care much about anything other than their profits.
But what can be done to change this situation? How can we protect the public from Internet-charlatans? How can one control the Internet? I wish I knew! But there are nevertheless means of directing consumers to those sites which do offer reliable information. Kite-marking high quality sites might be one way of achieving this. This task would, of course, be huge and difficult, but in the interest of public safety, governments and other official institutions should consider tackling it.
Colonic irrigation is the alternative therapy of celebrities (and those who like to imitate them): they tend to use it for all sorts of ailments, predominantly for loosing weight. And it works! When they have paid for the session, they are relieved of some cash as well as of about half a kilo of body weight. By the time they wake up the next morning, the money is still gone, but the weight is back. This is a most effective method for getting rid of some £s, but NOT an effective way for shedding a few pounds.
Numerous synonyms for colonic irrigation exist, e.g. colonic treatment, colon cleansing, rectal irrigation, colon therapy, colon hydrotherapy, colonic. The treatment is based on the ancient but obsolete theory of ‘autointoxication’, i.e. the body is assumed to poison itself with, ‘autotoxins’ which, in turn, cause various illnesses. So, it is implausible and there is also no evidence to suggest it is effective. But this does not stop professional organisations to make claims which are good for business.
My analysis of the claims made by professional organisations of practitioners of colonic irrigation across the globe aimed at assessing the therapeutic claims made by these institutions. Six such organisations were identified, and the contents of their websites were studied. The results showed that all of the six organisations make therapeutic claims on their websites. Frequently mentioned themes are ‘detoxification’, normalisation of intestinal functions, treatment of inflammatory bowel diseases and body weight reduction. The claims are mostly confined to symptomatic improvements – but there are exceptions, e.g. prevention of bowel cancer or sorting out Irritable Bowel Syndrome ‘once and for all’ . Other therapeutic claims pertain to asthma, menstrual irregularities, circulatory disorders, skin problems, improvement in energy levels and no longer requiring pharmacotherapy. All these claims represent testable hypotheses.
The question therefore arises whether these hypotheses have been tested and, if so, what the results of such investigations suggest? The use of colonic irrigation by alternative practitioners for any indications is not supported by any sound evidence at all. There are simply no trials to show effectiveness. Even worse is the fact that, although touted as safe, colonic irrigation can lead to serious complications.
The conclusion is therefore simple: colonic irrigation is neither demonstrably effective nor safe, and the information supplied by its professional organisations is therefore a significant contributor to the sea of misinformation in the realm of alternative medicine.
The UK ‘Society of Homeopaths’ (SoH) is the largest professional organisation of UK non-doctor, so-called lay- homeopaths. On their website, the SoH made very specific claims about homeopathy; in particular, they listed conditions for which homeopathy had allegedly been proven to be effective. These claims have now thoroughly been debunked, and the evidence the SoH produced in support of their claims has been shown to be misleading, cherry-picked or misinterpreted.
I have no idea who conducted the above-named investigation and made a youtube video of it, but I think it is essentially correct and well worth watching. My own experiences with the SoH relate mainly to two encounters.
The first was a complaint I made about one of their high-ranking officers, Ralf Jeutter. He had been promotiong homeopathic vaccinations on his website (needless to stress, I think, that there is no evidence to support the notion that homeopathic vaccinations are effective). As I felt that the SoH dragged their feet pursuing my complaint, I had to send several reminders. Eventually, they considered it and concluded that Reuter had done nothing wrong. This, presumably, is the reason why, even today, he can state on his website that Homeopathy is used to help individuals in dealing better with kinds of infections such as leptospirosis, meningitis and cholera. All is fine, it seems as long as a disclaimer is added: Any information obtained here is not to be construed as medical OR legal advice. The decision to vaccinate and how you implement that decision is yours and yours alone. The evidence for the efficacy of homeopathic immunisation is ‘anecdotal’. That means it is based on individuals’ reports past and present.
My second encounter with the SoH relates to my 2010 analysis of the SoH code of ethics and their adherence to it. The code demanded that:
- ‘all speculative theories will be stated as such and clearly distinguished’
- ‘no advertising may be used which expressly or implicitly claims to cure named diseases’
- ‘Advertising shall not be false, fraudulent, misleading, deceptive, extravagant or sensational.’
Encouraged by these assurances, I decided to study the websites of some members of the SoH, and soon discovered numerous and very obvious violations of the above-mentioned imperatives. In an attempt to find the root of these transgressions, I scrutinised the SoH’s own website where I found a multitude violations on all levels of the SoH’s own code of ethics. Many of the violations related to claims which were not supported by evidence. In other words, the largest professional UK organisation of lay- homeopaths misled the public in several rather devious ways:
they pretended to adhere to a code of ethics which forbids members to mislead the public
SoH -members nevertheless did mislead the public in ways that public health at risk
and they did so not least because the SoH followed exactly the same strategy
thus the SoH violated its own code of ethics to the detriment of public health.
My analysis was conducted a while ago, and some might hope that the SoH has stopped systematically misleading the public. This hope, however, is harshly disappointed when you watch the brand-new video entitled TESTING HOMEOPATHY mentioned above. As the SoH is about to celebrate 35 years of wisdom, courage, knowledge and prosperity, I do wonder whether this should not be 35 years of dangerously misleading the public.
What do you think?
Realgar, a commonly used traditional Chinese medicine, has – according to the teachings of Traditional Chinese Medicine (TCM) – acrid, bitter, warm, and toxic characteristics and is affiliated with the Heart, Liver and Stomach meridians. It is used internally against intestinal parasites and treat sore throats, and is applied externally to treat swelling, abscesses, itching, rashes, and other skin disorders.
Chemically, it is nothing other than arsenic sulphide. Despite its very well-known toxicity, is thought by TCM-practitioners to be safe, and it has been used in TCM under the name ‘Xiong Huang’ for many centuries. TCM-practitioners advise that the typical internal dose of realgar is between 0.2 and 0.4 grams, decocted in water and taken up to two times per day. Some practitioners may recommend slightly higher doses (0.3-0.9 grams). Larger doses of realgar may be used if it is being applied topically.
Toxicologists from Taiwan report a case of fatal realgar poisoning after short-term use of a topical realgar-containing herbal medicine.
A 24-year-old man with atopic dermatitis had received 18 days of oral herbal medicine and realgar-containing herbal ointments over whole body from a TCM-practitioner. Seven days later, he started to develop loss of appetite, dizziness, abdominal discomfort, an itching rash and skin scaling. Subsequently he suffered generalized oedema, nausea, vomiting, decreased urine amount, diarrhoea, vesico-oedematous exanthemas, malodorous perspiration, fever, and shortness of breath.
He was taken to hospital on day 19 when the dyspnoea became worse. Toxic epidermal necrolysis complicated with soft tissue infection and sepsis were then diagnosed. The patient died shortly afterwards of septic shock and multiple organ failure. Post-mortem blood arsenic levels were elevated at 1225 μg/L. The analysis of the patient’s herbal remedies yielded a very high concentration of arsenic in three unlabelled realgar-containing ointments (45427, 5512, and 4229 ppm).
The authors of this report concluded that realgar-containing herbal remedy may cause severe cutaneous adverse reactions. The arsenic in realgar can be absorbed systemically from repeated application to non-intact skin and thus should not be extensively used on compromised skin.
The notion that a treatment that ‘has stood the test of time’ must be safe and effective is very wide-spread in alternative medicine. This, we often hear, applies particularly to the external use of traditional remedies – what can be wrong with putting a traditional Chinese herbal cream on the skin?? This case, like so many others, should teach us that this appeal to tradition is a classical and often dangerous fallacy. And the ‘realgar-story’ also suggests that, in TCM, the ‘learning-curve’ is very flat indeed.
Chinese and Ayurvedic remedies are often contaminated with toxic heavy metals. But the bigger danger seems to be that some of these traditional ‘medicines’ contain such toxins because, according to ‘traditional wisdom’, these constituents have curative powers. I think that, until we have compelling evidence that any of these treatments do more good than harm, we should avoid taking them.
One of the most gratifying aspect of my work in Exeter was being able to offer posts to visiting researchers from across the world. Some of these co-workers, after returning to their home countries, became prominent scientists in their own right, and quite a few remained in contact and continued to collaborate with me or with members of my team. In one of these collaborative projects, we wanted to investigate adverse events attributed to traditional medical treatments in the Republic of Korea.
For this purpose, we reviewed adverse events recorded in the Republic of Korea, between 1999 and 2010, by the Food and Drug Administration, the Consumer Agency or the Association of Traditional Korean Medicine. Records of adverse events attributed to the use of traditional medical practices, including reports of medicinal accidents and consumers’ complaints, were evaluated.
Overall, 9624 records of adverse events were identified. Liver problems after the administration of herbal medicines were the most frequently reported adverse events. Only eight of the adverse events were recorded by the pharmacovigilance system run by the Food and Drug Administration. Of the 9624 events, 1389 – mostly infections, cases of pneumothorax and burns – were linked to physical therapies (n = 285) or acupuncture/moxibustion (n = 1104).
We concluded that traditional medical practices often appear to have adverse effects, yet almost all of the adverse events attributed to such practices between 1999 and 2010 were missed by the national pharmacovigilance system. The Consumer Agency and the Association of Traditional Korean Medicine should be included in the national pharmacovigilance system.
The assumption that alternative treatments are entirely harmless is widespread, not least because it is incessantly promoted via millions of web-site, thousands of books, newspaper articles, VIPs like Prince Charles etc. etc. Consumers are incessantly being told that NATURAL = SAFE. Yet, if we look closely, most alternative treatments are not natural and, as this investigation demonstrates, they are certainly not devoid of risks.
I already see the apologists preparing to comment that, compared to conventional therapies, alternative treatments are very safe. So let me pre-empt this fallacy by pointing out (yet again) that 1) in the absence of adequate surveillance systems, nobody can say how frequent adverse-effects of alternative treatments really are, and that 2) even severe adverse effects can normally be tolerated, if the treatment in question has been shown to be efficacious.
So, instead of commenting on my repeated reports about the risks of alternative medicine, I invite, in fact, I challenge my critics to answer this simple question: For how many alternative therapies is there a well-documented positive risk/benefit balance?
Swiss chiropractors have just published a clinical trial to investigate outcomes of patients with radiculopathy due to cervical disk herniation (CDH). All patients had neck pain and dermatomal arm pain; sensory, motor, or reflex changes corresponding to the involved nerve root and at least one positive orthopaedic test for cervical radiculopathy were included. CDH was confirmed by magnetic resonance imaging. All patients received regular neck manipulations.
Baseline data included two pain numeric rating scales (NRSs), for neck and arm, and the Neck Disability Index (NDI). At two, four and twelve weeks after the initial consultation, patients were contacted by telephone, and the data for NDI, NRSs, and patient’s global impression of change were collected. High-velocity, low-amplitude thrusts were administered by experienced chiropractors. The proportion of patients reporting to feel “better” or “much better” on the patient’s global impression of change scale was calculated. Pre-treatment and post-treatment NRSs and NDIs were analysed.
Fifty patients were included. At two weeks, 55.3% were “improved,” 68.9% at four and 85.7% at twelve weeks. Statistically significant decreases in neck pain, arm pain, and NDI scores were noted at 1 and 3 months compared with baseline scores. 76.2% of all sub-acute/chronic patients were improved at 3 months.
The authors concluded that most patients in this study, including sub-acute/chronic patients, with symptomatic magnetic resonance imaging-confirmed CDH treated with spinal manipulative therapy, reported significant improvement with no adverse events.
In the presence of disc herniation, chiropractic manipulations have been described to cause serious complications. Some experts therefore believe that CDH is a contra-indication for spinal manipulation. The authors of this study imply, however, that it is not – on the contrary, they think it is an effective intervention for CDH.
One does not need to be a sceptic to notice that the basis for this assumption is less than solid. The study had no control group. This means that the observed effect could have been due to:
a placebo response,
the regression towards the mean,
the natural history of the condition,
or other factors which have nothing to do with the chiropractic intervention per se.
And what about the interesting finding that no adverse-effects were noted? Does that mean that the treatment is safe? Sorry, but it most certainly does not! In order to generate reliable results about possibly rare complications, the study would have needed to include not 50 but well over 50 000 patients.
So what does the study really tell us? I have pondered over this question for some time and arrived at the following answer: NOTHING!
Is that a bit harsh? Well, perhaps yes. And I will revise my verdict slightly: the study does tell us something, after all – chiropractors tend to confuse research with the promotion of very doubtful concepts at the expense of their patients. I think, there is a name for this phenomenon: PSEUDO-SCIENCE.
Upper spinal manipulation, the signature-treatment of many chiropractors is by no means free of serious risks. Most chiropractors negate this, but can any reasonable person deny it? Neurosurgeons from New York have just published an interesting case-report in this context:
A 45 year old male with presented to his internist with a two-week history of right sided neck pain and tenderness, accompanied by tingling in the hand. The internists’ neurological examination revealed nothing abnormal, except for a decreased range of motion of the right arm. He referred the patient to a chiropractor who performed plain X-rays which apparently showed “mild spasm” (how anyone can see spasm on an X-ray is beyond me!). No magnetic resonance imaging study was done.
The chiropractor proceeded manipulating the patient’s neck on two successive days. By the morning of the third visit, the patient reported extreme pain and difficulty walking. Without performing a new neurological examination or obtaining a magnetic resonance study, the chiropractor manipulated the patient’s neck for a third time.
Thereafter, the patient immediately became quadriplegic. Despite undergoing an emergency C5 C6 anterior cervical diskectomy/fusion to address a massive disc found on the magnetic resonance scan, the patient remained quadriplegic. There seemed to be very little doubt that the quadriplegia was caused by the chiropractic spinal manipulation.
The authors of this report also argue that a major point of negligence in this case was the failure of both the referring internist and chiropractor to order a magnetic resonance study of the cervical spine prior to the chiropractic manipulations. In his defence, the internist claimed that there was no known report of permanent quadriplegia resulting from neck manipulation in any medical journal, article or book, or in any literature of any kind or on the internet. Even the quickest of literature searches discloses this assumption to be wrong. The first such case seems to have been published as early as 1957. Since then, numerous similar reports have been documented in the medical literature.
The internist furthermore claimed that the risk of this injury must be vanishingly small given the large numbers of manipulations performed annually. As we have pointed out repeatedly, this argument is pure speculation; under-reporting of such cases is huge, and therefore exact incidence figures are anybody’s guess.
The patient sued both the internist and the chiropractor, and the total amount of the verdict was $14,596,000.00 the internist’s liability was 5% ($759,181.65).
A cult can be defined not just in a religious context, but also as a” usually nonscientific method or regimen claimed by its originator to have exclusive or exceptional power in curing a particular disease.” After ~20 years of researching this area, I have come to suspect that much of alternative medicine resembles a cult – a bold statement, so I better explain.
One characteristic of a cult is the unquestioning commitment of its members to the bizarre ideas of their iconic leader. This, I think, chimes with several forms alternative medicine. Homeopaths, for instance, very rarely question the implausible doctrines of Hahnemann who, to them, is some sort of a semi-god. Similarly, few chiropractors doubt even the most ridiculous assumptions of their founding father, D D Palmer who, despite of having been a somewhat pathetic figure, is uncritically worshipped. By definition, a cult-leader is idealised and thus not accountable to anyone; he (yes, it is almost invariably a male person) cannot be proven wrong by logic arguments nor by scientific facts. He is quite simply immune to any form of scrutiny. Those who dare to disagree with his dogma are expelled, punished, defamed or all of the above.
Cults tend to brain-wash their members into unconditional submission and belief. Likewise, fanatics of alternative medicine tend to be brain-washed, i.e. systematically misinformed to the extend that reality becomes invisible. They unquestioningly believe in what they have been told, in what they have read in their cult-texts, and in what they have learnt from their cult-peers. The effects of this phenomenon can be dramatic: the powers of discrimination of the cult-member are reduced, critical questions are discouraged, and no amount of evidence can dissuade the cult-member from abandoning even the most indefensible concepts. Internal criticism is thus by definition non-existent.
Like religious cults, many forms of alternative medicine promote an elitist concept. Cult-members become convinced of their superiority, based not on rational considerations but on irrational beliefs. This phenomenon has a range of consequences. It leads to the isolation of the cult-member from the rest of the world. By definition, critics of the cult do not belong to the elite; they are viewed as not being able to comprehend the subtleties of the issues at hand and are thus ignored or not taken seriously. For cult-members, external criticism is thus non-existent or invalid.
Cult-members tend to be on a mission, and so are many enthusiasts of alternative medicine. They use any conceivable means to recruit new converts. For instance, they try to convince family, friends and acquaintances of their belief in their particular alternative therapy at every conceivable occasion. They also try to operate on a political level to popularize their cult. They cherry pick data, often argue emotionally rather than rationally, and ignore all arguments which contradict their belief system.
Cult-members, in their isolation from society, tend to be assume that there is little worthy of their consideration outside the cult. Similarly, enthusiasts of alternative medicine tend to think that their treatment is the only true method of healing. Therapies, concepts and facts which are not cult-approved are systematically defamed. An example is the notion of BIG PHARMA which is employed regularly in alternative medicine. No reasonable person assumes that the pharmaceutical industry smells of roses. However, the exaggerated and systematic denunciation of this industry and its achievements is a characteristic of virtually all branches of alternative medicine. Such behaviour usually tells us more about the accuser than the accused.
There are many other parallels between a cult and alternative medicine, I am sure. In my view, the most striking one must be the fact that any spark of cognitive dissonance in the cult-victim is being extinguished by highly effective and incessant flow of misinformation which often amounts to a form of brain-washing.
Some people will probably think that I am obsessed with writing about the risk of chiropractic. True, I have published quite a bit on this subject, both in the peer-reviewed literature as well as on this blog - but not because I am obsessed; on this blog, I will re-visit the topic every time a relevant new piece of evidence becomes available because it is indisputably such an important subject. Writing about it might prevent harm.
So far, we know for sure that mild to moderate as well as serious complications, including deaths, do occur after chiropractic spinal manipulations, particularly those of the upper spine. What we cannot say with absolute certainty is whether they are caused by the treatment or whether they happened coincidentally. Our knowledge in this area relies mostly on case-reports and surveys which, by their very nature, do not allow causal inferences. Therefore chiropractors have, in the past, been able to argue that a causal link remains unproven.
A brand-new blinded parallel group RCT might fill this gap in our knowledge and might reject or establish the notion of causality once and for all. The authors’ objective was to establish the frequency and severity of adverse effects from short term usual chiropractic treatment of the spine when compared to a sham treatment group. They thus conducted the first ever RCT with the specific aim to examine the occurrence of adverse events resulting from chiropractic treatment. It was conducted across 12 chiropractic clinics in Perth, Western Australia. The participants comprised 183 adults, aged 20-85, with spinal pain. Ninety two participants received individualized care consistent with the chiropractors’ usual treatment approach; 91 participants received a sham intervention. Each participant received two treatment sessions.
Completed adverse questionnaires were returned by 94.5% of the participants after the first appointment and 91.3% after the second appointment. Thirty three per cent of the sham group and 42% of the usual care group reported at least one adverse event. Common adverse events were increased pain (sham 29%; usual care 36%), muscle stiffness (sham 29%; usual care 37%), headache (sham 17%; usual care 9%). The relative risk was not significant for either adverse event occurrence (RR = 1.24 95% CI 0.85 to 1.81); occurrence of severe adverse events (RR = 1.9; 95% CI 0.98 to 3.99); adverse event onset (RR = 0.16; 95% CI 0.02 to 1.34); or adverse event duration (RR = 1.13; 95% CI 0.59 to 2.18). No serious adverse events were reported.
The authors concluded that a substantial proportion of adverse events following chiropractic treatment may result from natural history variation and non-specific effects.
If we want to assess causality of effects, we have no better option than to conduct an RCT. It is the study design that can give us certainty, or at least near certainty - that is, if the RCT is rigorous and well-made. So, does this study reject or confirm causality? The disappointing truth is that it does neither.
Adverse events were clearly more frequent with real as compared to sham-treatment. Yet the difference failed to be statistically significant. Why? There are at least two possibilities: either there was no true difference and the numerically different percentages are a mere fluke; or there was a true difference but the sample size was too small to prove it.
My money is on the second option. The number of patients was, in my view, way too small for demonstrating differences in frequencies of adverse effects. This applies to the adverse effects noted, but also, and more importantly, to the ones not noted.
The authors state that no serious adverse effects were observed. With less that 200 patients participating, it would have been most amazing to see a case of arterial dissection or stroke. From all we currently know, such events are quite rare and occur perhaps in one of 10 000 patients or even less often. This means that one would require a trial of several hundred thousand patients to note just a few of such events, and an RCT with several million patients to see a difference between real and sham treatment. It seems likely that such an undertaking will never be affordable.
So, what does this new study tell us? In my view, it is strong evidence to suggest a causal kink between chiropractic treatment and mild to moderate adverse effects. I dose not prove it, but merely suggests it - yet I am fairly sure that chiropractors, once again, will not agree with me.