MD, PhD, FMedSci, FSB, FRCP, FRCPEd

systematic review

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The discussion whether acupuncture is more than a placebo is as long as it is heated. Crucially, it is also quite tedious, tiresome and unproductive, not least because no resolution seems to be in sight. Whenever researchers develop an apparently credible placebo and the results of clinical trials are not what acupuncturists had hoped for, the therapists claim that the placebo is, after all, not inert and the negative findings must be due to the fact that both placebo and real acupuncture are effective.

Laser acupuncture (acupoint stimulation not with needle-insertion but with laser light) offers a possible way out of this dilemma. It is relatively easy to make a placebo laser that looks convincing to all parties concerned but is a pure and inert placebo. Many trials have been conducted following this concept, and it is therefore highly relevant to ask what the totality of this evidence suggests.

A recent systematic review did just that; specifically, it aimed to evaluate the effects of laser acupuncture on pain and functional outcomes when it is used to treat musculoskeletal disorders.

Extensive literature searches were used to identify all RCTs employing laser acupuncture. A meta-analysis was performed by calculating the standardized mean differences and 95% confidence intervals, to evaluate the effect of laser acupuncture on pain and functional outcomes. Included studies were assessed in terms of their methodological quality and appropriateness of laser parameters.

Forty-nine RCTs met the inclusion criteria. Two-thirds (31/49) of these studies reported positive effects. All of them were rated as being of high methodological quality and all of them included sufficient details about the lasers used. Negative or inconclusive studies mostly failed to demonstrate these features. For all diagnostic subgroups, positive effects for both pain and functional outcomes were more consistently seen at long-term follow-up rather than immediately after treatment.

The authors concluded that moderate-quality evidence supports the effectiveness of laser acupuncture in managing musculoskeletal pain when applied in an appropriate treatment dosage; however, the positive effects are seen only at long-term follow-up and not immediately after the cessation of treatment.

Surprised? Well, I am!

This is a meta-analysis I always wanted to conduct and never came round to doing. Using the ‘trick’ of laser acupuncture, it is possible to fully blind patients, clinicians and data evaluators. This eliminates the most obvious sources of bias in such studies. Those who are convinced that acupuncture is a pure placebo would therefore expect a negative overall result.

But the result is quite clearly positive! How can this be? I can see three options:

  • The meta-analysis could be biased and the result might therefore be false-positive. I looked hard but could not find any significant flaws.
  • The primary studies might be wrong, fraudulent etc. I did not see any obvious signs for this to be so.
  • Acupuncture might be more than a placebo after all. This notion might be unacceptable to sceptics.

I invite anyone who sufficiently understands clinical trial methodology to scrutinise the data closely and tell us which of the three possibilities is the correct one.

Chinese proprietary herbal medicines (CPHMs) are a well-established and a hugely profitable part of Traditional Chinese Medicine (TCM) with a long history in China and elsewhere; they are used for all sorts of conditions, not least for the treatment of common cold. Many CPHMs have been listed in the ‘China national essential drug list’ (CNEDL), the official reference published by the Chinese Ministry of Health. One would hope that such a document to be based on reliable evidence – but is it?

The aim of a recent review was to provide an assessment on the potential benefits and harms of CPHMs for common cold listed in the CNEDL.

The authors of this assessment were experts from the Chinese ‘Centre for Evidence-Based Medicine’ and one well-known researcher of alternative medicine from the UK. They searched CENTRAL, MEDLINE, EMBASE, SinoMed, CNKI, VIP, China Important Conference Papers Database, China Dissertation Database, and online clinical trial registry websites from their inception to 31 March 2013 for clinical studies of CPHMs listed in the CNEDL for common cold.

Of the 33 CPHMs listed in the 2012 CNEDL for the treatment of common cold, only 7 had any type of clinical trial evidence at all. A total of 6 randomised controlled trials (RCTs) and 7 case series (CSs) could be included in the assessments.

All these studies had been conducted in China and published in Chinese. All of them were burdened with poor study design and low methodological quality, and all had to be graded as being associated with a very high risk of bias.

The authors concluded that the use of CPHMs for common cold is not supported by robust evidence. Further rigorous well designed placebo-controlled, randomized trials are needed to substantiate the clinical claims made for CPHMs.

I should state that it is, in my view, most laudable that the authors draw such a relatively clear, negative conclusion. This does certainly not happen often with papers originating from China, and George Lewith, the UK collaborator in this article, is also not known for his critical attitude towards alternative medicine. But there are other, less encouraging issues here to mention.

In the discussion section of their paper, the authors mention that the CNEDL has been approved by the Chinese Ministry of Public Health and is currently regarded as the accepted reference point for the medicines used in China. They also explain that the CNEDL was officially launched and implemented in August 2009. The CNEDL is now up-dated every 3 years, and its 2012 edition contains 520 medicines, including 203 CPHMs. The CPHMs listed in CNEDL cover 137 herbal remedies for internal medicine, 11 for surgery, 20 for gynaecology, 7 for ophthalmology, 13 for otorhinolaryngology and 15 for orthopaedics and traumatology.

Moreover, the authors inform us that about 3,100 medical and clinical experts had been recruited to evaluate the safety, effectiveness and costs of CPHMs. The selection process of medicines into CNEDL was strictly in accordance with the principle that they ‘must be preventive and curative, safe and effective, affordable, easy to use, think highly of both Chinese and Western medicine’. A detailed procedure for evaluation is, however, not available because the files are confidential.

The authors finally state that their paper demonstrates that the selection of CPHMs into the CNEDL is less likely to be ‘evidence-based’ and revealed the sharp contrast between the policy and priority given to by the Chinese government to Traditional Chinese Medicine(TCM).

This surely must be a benign judgement, if there ever was one! I would say that the facts disclosed in this review show that TCM seems to exist in a strange universe where commercial interests are officially allowed to reign supreme over patients’ interests and public health.

Neck pain is a common problem which often causes significant disability. Chiropractic manipulation has become one of the most popular forms of alternative treatment for such symptoms. This seems surprising considering that neck manipulations are neither convincingly effective nor free of adverse effects.

The current Cochrane review on this subject could not be clearer: “Done alone, manipulation and/or mobilization were not beneficial; when compared to one another, neither was superior.” In the absence of compelling evidence for efficacy, any risk of neck manipulation would tilt the risk/benefit balance into the negative.

Adverse effects of neck manipulations range from mild symptoms, such as local neck tenderness or stiffness, to more severe injuries involving the spinal cord, peripheral nerve roots, and arteries within the neck. A recent paper reminds us that another serious complication has to be added to this already long list: phrenic nerve injury.

The phrenic nerve is responsible for controlling the contractions of the diaphragm, which allows the lungs to take in and release air and make us breathe properly. The phrenic nerve is formed from C3, C4, and C5 nerve fibres and descends along the anterior surface of the scalenus anterior muscle before entering the thorax to supply motor and sensory input to the diaphragm. Its anatomic location in the neck leaves it vulnerable to traumatic injury. Phrenic nerve injury can result in paralysis of the diaphragm and often leads to deteriorating function of the diaphragm, which can lead to partial or complete paralysis of the muscle and, as a result, serious breathing problems.

Patients who experience such problems may require emergency medical treatment or surgery. Sudden, severe damage to the phrenic nerve can make it impossible for the diaphragm to contract on its own. In order to make sure that the patient can breathe, a breathing tube needs to be inserted, a process called intubation. Artificial respiration would then be required.

American neurologists published a case report of a healthy man who consulted a chiropractor for his neck pain. Predictably, the chiropractor employed cervical manipulation to treat this condition. The result was bilateral diaphragmatic paralysis.

Similar cases have been reported previously, for instance, here and here and here and here. Damage to other nerves has also been documented to be a possible complication of spinal manipulation, for instance, here and here.

The authors of this new case report conclude that physicians must be aware of this complication and should be cautious when recommending spinal manipulation for the treatment of neck pain, especially in the presence of preexisting degenerative disease of the cervical spine.

I know what my chiropractic friends will respond to this post:

  • I am alarmist,
  • I cherry-pick articles that are negative for their profession,
  • these cases are extreme rarities,
  • conventional medicine is much more dangerous.

To this I reply: Imagine a conventional therapy about which the current Cochrane review says that it has no proven effect for the condition in question. Imagine further that this therapy causes mild to moderate adverse effects in about 50% of all patients in addition to very dramatic complications which are probably rare but, as no monitoring system exists, of unknown frequency. Imagine now that the professionals using this treatment more regularly than any other clinicians steadfastly deny that the risk/benefit balance is way out of kilter.

Would you call someone who repeatedly tries to warn the public of this situation ‘alarmist’?

Would you not consider the professionals who continue to practice the therapy in question to be irresponsible?

Iyengar Yoga, named after and developed by B. K. S. Iyengar, is a form of Hatha Yoga that has an emphasis on detail, precision and alignment in the performance of posture (asana) and breath control (pranayama). The development of strength, mobility and stability is gained through the asanas.

B.K.S. Iyengar has systematised over 200 classical yoga poses and 14 different types of Pranayama (with variations of many of them) ranging from the basic to advanced. This helps ensure that students progress gradually by moving from simple poses to more complex ones and develop their mind, body and spirit step by step.

Iyengar Yoga often makes use of props, such as belts, blocks, and blankets, as aids in performing asanas (postures). The props enable students to perform the asanas correctly, minimising the risk of injury or strain, and making the postures accessible to both young and old.

Sounds interesting? But does it work?

The objective of this recent systematic review was to conduct a systematic review of the existing research on Iyengar yoga for relieving back and neck pain. The authors conducted extensive literature searches and found 6 RCTs that met the inclusion criteria.

The difference between the groups on the post-intervention pain or functional disability intensity assessment was, in all 6 studies, favouring the yoga group, which projected a decrease in back and neck pain.

The authors concluded that Iyengar yoga is an effective means for both back and neck pain in comparison to control groups. This systematic review found strong evidence for short-term effectiveness, but little evidence for long-term effectiveness of yoga for chronic spine pain in the patient-centered outcomes.

So, if we can trust this evidence (I would not call the evidence ‘strong), we have yet another treatment that might be effective for acute back and neck pain. The trouble, I fear, is not that we have too few such treatments, the trouble seems to be that we have too many of them. They all seem similarly effective, and I cannot help but wonder whether, in fact, they are all similarly ineffective.

Regardless of the answer to this troubling question, I feel the need to re-state what I have written many times before: FOR A CONDITION WITH A MULTITUDE OF ALLEGEDLY EFFECTIVE THERAPIES, IT MIGHT BE BEST TO CHOSE THE ONE THAT IS SAFEST AND CHEAPEST.

If we go on the internet, we find no end of positive claims for TM. The official TM website, for instance, claims that more than 350 peer-reviewed research studies on the TM technique have been published in over 160 scientific journals. These studies were conducted at many US and international universities and research centers, including Harvard Medical School, Stanford Medical School, Yale Medical School, and UCLA Medical School.

This may well be true – but do those studies amount to more than a heap of beans? Let’s find out.

The objective of our Cochrane review was to determine the effectiveness of TM for the primary prevention of cardiovascular disease (CVD). We searched the following electronic databases: the Cochrane Central Register of Controlled Trials (CENTRAL) (2013, Issue 10); MEDLINE (Ovid) (1946 to week three November 2013); EMBASE Classic and EMBASE (Ovid) (1947 to week 48 2013); ISI Web of Science (1970 to 28 November 2013); and Database of Abstracts of Reviews of Effects (DARE) and Health Technology Assessment Database and Health Economics Evaluations Database (November 2013). We also searched the Allied and complementary Medicine Database (AMED) (inception to January 2014) and IndMed (inception to January 2014). We hand searched trial registers and reference lists of reviews and articles and contacted experts in the field. We applied no language restrictions.

We included randomised controlled trials (RCTs) of at least three months’ duration involving healthy adults or adults at high risk of CVD. Trials examined TM only and the comparison group was no intervention or minimal intervention. We excluded trials that involved multi-factorial interventions. Outcomes of interest were clinical CVD events (cardiovascular mortality, all-cause mortality and non-fatal events) and major CVD risk factors (e.g. blood pressure and blood lipids, occurrence of type 2 diabetes, quality of life, adverse events and costs). Two authors independently selected trials for inclusion, extracted data and assessed the risk of bias.

We identified 4 RCTs with a total of 430 participants for inclusion in this review. The included trials were small, short term (three months) and at risk of bias. In all studies, TM was practised for 15 to 20 minutes twice a day. None of the included studies reported all-cause mortality, cardiovascular mortality or non-fatal endpoints as trials were short term, but one study reported survival rate three years after the trial was completed. In view of the considerable statistical heterogeneity between the results of the studies for the only outcomes reported, systolic blood pressure (I2 = 72%) and diastolic blood pressure (I2 = 66%), we decided not to undertake a meta-analysis. None of the four trials reported blood lipids, occurrence of type 2 diabetes, adverse events, costs or quality of life.

We concluded that there are few trials with limited outcomes examining the effectiveness of TM for the primary prevention of CVD. Due to the limited evidence to date, we could draw no conclusions as to the effectiveness of TM for the primary prevention of CVD. There was considerable heterogeneity between trials and the included studies were small, short term and at overall serious risk of bias. More and larger long-term, high-quality trials are needed.

Even though I am a co-author of this review, I am not entirely sure that the last sentence of our conclusion is totally correct. The TM movement has, in my view, all the characteristics of a cult with all its the dangers that cults entail. This means, I think, we ought to be cautious about TM and sceptical about their research and results. At the risk of provoking harsh criticism, I would even say we should be distrustful of their aims and methods.

- Chronic low back pain (CLBP) is a condition which affects so many people that it represents a huge burden to individual patients’ suffering as well as to society in terms of loss of work time and increased economic cost. The number of therapies that have been claimed to be effective for CLBP can hardly be counted. Two of the most common treatments are spinal manipulation and exercise.

The purpose of this systematic review was to determine the effectiveness of spinal manipulation vs prescribed exercise for patients diagnosed with CLBP. Only RCTs that compared head-to-head spinal manipulation to an exercise group were included in this review.

A search of the current literature was conducted using a keyword process in CINAHL, Cochrane Register of Controlled Trials Database, Medline, and Embase. The searches included studies available up to August 2014. Studies were included based on PICOS criteria 1) individuals with CLBP defined as lasting 12 weeks or longer; 2) spinal manipulation performed by a health care practitioner; 3) prescribed exercise for the treatment of CLBP and monitored by a health care practitioner; 4) measurable clinical outcomes for reducing pain, disability or improving function; 5) randomized controlled trials. The methodological quality of all included articles was determined using the criteria developed and used by the Physiotherapy Evidence Database (PEDro).

Only three RCTs met the inclusion criteria of this systematic review. The outcomes used in these studies included Disability Indexes, Pain Scales and function improvement scales. One RCT found spinal manipulation to be more effective than exercise, and the results of another RCT indicated the reverse. The third RCT found both interventions offering equal effects in the long term.

The author concluded that there is no conclusive evidence that clearly favours spinal manipulation or exercise as more effective in treatment of CLBP. More studies are needed to further explore which intervention is more effective.

Whenever there are uncounted treatments for a given condition, one has to ask oneself whether they are all similarly effective or equally ineffective. The present review does unfortunately not answer this question, but I fear the latter might be more true than the former.

Considering how much money we spend on treating CLBP, it is truly surprising to see that just three RCTs are available comparing two of the most commonly used treatments for this condition. Equally surprising is the fact that we simply cannot tell, on the basis of these data, which of the two therapies is more effective.

What consequences should we draw from this information. Obviously we need more high quality trials. But what should we do in the meantime?

Whenever two treatments are equally effective (or, in this case, perhaps equally ineffective?), we must consider other important criteria such as safety and cost. Regular chiropractic care (chiropractors use spinal manipulation on almost every patient, while osteopaths and physiotherapists employ it less frequently)  is neither cheap nor free of serious adverse effects such as strokes; regular exercise has none of these disadvantages. In view of these undeniable facts, it is hard not to come up with anything other than the following recommendation: until new and compelling evidence becomes available, exercise ought to be preferred over spinal manipulation as a treatment of CLBP – and consequently consulting a chiropractor should not be the first choice for CLBP patients.

Moxibustion is an ancient variation of acupuncture using  moxa made from dried mugwort (Artemisia argyi). It has long played an important role in the traditional heath care systems of China and other Asian countries. More recently, it has become popular also in the West. Practitioners use moxa sticks indirectly to warm acupuncture needles, or burn it close to the patient’s skin. Essentially, moxibustion is a treatment where acupuncture points are stimulated mainly or exclusively by the heat of burning moxa.

Because of moxibustion’s long history of usage and the fact that it is employed in many countries for a very wide range of conditions, some might argue that it has stood the ‘test of time’ and should be considered to be a well-established therapy. More critical thinkers would, however, point out that this is not an argument but a classical fallacy.

My team at Exeter regularly had research fellows from Korea and other Asian countries, and we managed to develop a truly productive cooperation. It enabled us to conduct systematic reviews including the Asian literature – and this is how we got involved in an unusual amount of research into moxibustion which, after all, is a fairly exotic alternative therapy. In 2010, we began a series of systematic reviews of moxibustion.

One of the first such articles included 9 RCTs testing the effectiveness of this treatment for stroke rehabilitation. Three RCTs reported favorable effects of moxibustion plus standard care on motor function versus standard care alone Three randomized clinical trials compared the effects of moxibustion on activities of daily living alone but failed to show favorable effects of moxibustion.

Also in 2010, our systematic review of RCTs of moxibustion as a treatment of ulcerative colitis (UC) concluded that current evidence is insufficient to show that moxibustion is an effective treatment of UC. Most of included trials had high risk of bias. More rigorous studies seem warranted.

Our (2010) systematic review od RCTs of moxibustion as a therapy in cancer care found that the evidence was limited to suggest moxibustion is an effective supportive cancer care in nausea and vomiting. However, all studies had a high risk of bias so effectively there was not enough evidence to draw any conclusion.

Our (2010) systematic review of RCTs of moxibustion for treating hypertension concluded that there was insufficient evidence to suggest that moxibustion is an effective treatment for hypertension.

Our (2010) systematic review of RCTs of moxibustion for constipation concluded as follows: Given that the methodological quality of all RCTs was poor, the results from the present review are insufficient to suggest that moxibustion is an effective treatment for constipation. More rigorous studies are warranted.

Our (2010) systematic review found few RCTs were available that test the effectiveness of moxibustion in the management of pain, and most of the existing trials had a high risk of bias. Therefore, more rigorous studies are required before the effectiveness of moxibustion for the treatment of pain can be determined.

Our (2011) systematic review of 14 RCTs of moxibustion for rheumatic conditions failed to provide conclusive evidence for the effectiveness of moxibustion compared with drug therapy in rheumatic conditions.

The, so far, last article in this series has only just been published. The purpose of this systematic review was to assess the efficacy of moxibustion as a treatment of chemotherapy-induced leukopenia. Twelve databases were searched from their inception through June 2014, without a language restriction. Randomized clinical trials (RCTs) were included, if moxibustion was used as the sole treatment or as a part of a combination therapy with conventional drugs for leukopenia induced by chemotherapy. Cochrane criteria were used to assess the risk of bias.

Six RCTs with a total of 681 patients met our inclusion criteria. All of the included RCTs were associated with a high risk of bias. The trials included patients with various types of cancer receiving ongoing chemotherapy or after chemotherapy. The results of two RCTs suggested the effectiveness of moxibustion combined with chemotherapy vs. chemotherapy alone. In four RCTs, moxibustion was more effective than conventional drug therapy. Six RCTs showed that moxibustion was more effective than various types of control interventions in increasing white blood cell counts.

Our conclusion: there is low level of evidence based on these six trials that demonstrates the superiority of moxibustion over drug therapies in the treatment of chemotherapy-induced leukopenia. However, the number of trials, the total sample size, and the methodological quality are too low to draw firm conclusions. Future RCTs appear to be warranted.

Was all this research for nothing?

I know many people who would think so. However, I disagree. If nothing else, these articles demonstrated several facts quite clearly:

  • There is quite a bit of research even on the most exotic alternative therapy; sometimes one needs to look hard and include languages other than English.
  • Studies from China and other Asian counties very rarely report negative results; this fact casts a dark shadow on the credibility of such data.
  • The poor quality of trials in most areas of alternative medicine is lamentable and must be stimulus for researchers in this field to improve their act.
  • Authors of systematic reviews must resist the temptation to draw positive conclusions based on flawed primary data.
  • Moxibustion is a perfect example for demonstrating that the ‘test of time’ is no substitute for evidence.
  • As for moxibustion, it cannot currently be considered an evidence-based treatment for any condition.

On this blog and elsewhere, I have repeatedly cast doubt on the efficacy of homeopathy – not because I have ‘an axe to grind’, as some seem to believe, but because

  1. the assumptions which underpin homeopathy fly in the face of science,
  2. the clinical evidence fails to show that it works beyond a placebo effect.

But was I correct?

A new systematic review and meta-analysis seems to indicate that I was mistaken. It tested the hypothesis that the outcome of an individualised homeopathic treatment (homeopaths would argue that this is the only true approach to homeopathy) is distinguishable from that with placebos.

The review’s methods, including literature search strategy, data extraction, assessment of risk of bias and statistical analysis, were strictly protocol-based. Judgment in seven assessment domains enabled a trial’s risk of bias to be designated as low, unclear or high. A trial was judged to comprise ‘reliable evidence’ if its risk of bias was low or was unclear in one specified domain. ‘Effect size’ was reported as odds ratio (OR), with arithmetic transformation for continuous data carried out as required; OR > 1 signified an effect favouring homeopathy.

Thirty-two eligible RCTs studied 24 different medical conditions in total. Twelve trials were classed ‘uncertain risk of bias’, three of which displayed relatively minor uncertainty and were designated reliable evidence; 20 trials were classed ‘high risk of bias’. Twenty-two trials had extractable data and were subjected to meta-analysis; OR = 1.53 (95% confidence interval (CI) 1.22 to 1.91). For the three trials with reliable evidence, sensitivity analysis revealed OR = 1.98 (95% CI 1.16 to 3.38).

The authors arrived at the following conclusion: medicines prescribed in individualised homeopathy may have small, specific treatment effects. Findings are consistent with sub-group data available in a previous ‘global’ systematic review. The low or unclear overall quality of the evidence prompts caution in interpreting the findings. New high-quality RCT research is necessary to enable more decisive interpretation.

One does not need to be a prophet to predict that the world of homeopathy will declare this article as the ultimate proof of homeopathy’s efficacy beyond placebo. Already the ‘British Homeopathic Association’ has issued the following press release:

Clinical evidence for homeopathy published

Research into the effectiveness of homeopathy as an individualised treatment has produced results that may surprise many from the worlds of science and medicine. The conclusions are reported cautiously, but the new publication is the first of its type to present evidence that medicines prescribed in individualised homeopathy may have specific effects.

The paper, published in the peer-reviewed journal Systematic Reviews,1 reports a rigorous systematic review and meta-analysis of 32 randomised controlled trials (RCTs) in which homeopathic medicines were prescribed on an individual basis to each participant, depending on their particular symptoms.

The overall quality of the RCT evidence was found to be low or unclear, preventing the researchers from reaching decisive conclusions. Three RCTs were identified as “reliable evidence”.

The study was led by Dr Robert Mathie, research development adviser for the British Homeopathic Association, in partnership with a number of collaborators, including colleagues at the Robertson Centre for Biostatistics, University of Glasgow, who independently verified the statistical methods and findings.

“What we found from the statistics,” says Dr Mathie, “is that the effect of individualised treatment using homeopathic medicines was significantly greater than placebos, and that this effect was retained when we included only the three trials with reliable evidence. This tentatively provides proof of concept that homeopathic medicines have clinical treatment effects.”

Surprised? I was stunned and thus studied the article in much detail (luckily the full text version is available online). Then I entered into an email exchange with the first author who I happen to know personally (to his credit, he responded regularly). In the end, this conversation helped me to better understand the review’s methodology; but it also resulted in me being very much underwhelmed by the reliability of the authors’ conclusion.

Normally I would now explain why. But, in this particular case, I thought it would be interesting and helpful to give others the opportunity to examine the article and come up with their own comments. Subsequently I will add my criticisms.

SO PLEASE TAKE SOME TIME TO STUDY THIS PAPER AND TELL US WHAT YOU THINK.

The regular consumption of fish-oil has a potentially favourable role in inflammation, carcinogenesis inhibition and cancer outcomes. An analysis of the literature aimed to review the evidence for the roles of dietary-fish and fish-oil intake in prostate-cancer (PC) risk, aggressiveness and mortality.

A systematic-review, following PRISMA guidelines was conducted. PubMed, MEDLINE and Embase were searched to explore PC-risk, aggressiveness and mortality associated with dietary-fish and fish-oil intake. 37 studies were selected.

A total of 37-studies with 495,321 participants were analysed. They revealed various relationships regarding PC-risk (n = 31), aggressiveness (n = 8) and mortality (n = 3). Overall, 10 studies considering PC-risk found significant inverse trends with fish and fish-oil intake. One found a dose–response relationship whereas greater intake of long-chain-polyunsaturated fatty acids increased risk of PC when considering crude odds-ratios [OR: 1.36 (95% CI: 0.99–1.86); p = 0.014]. Three studies addressing aggressiveness identified significant positive relationships with reduced risk of aggressive cancer when considering the greatest intake of total fish [OR 0.56 (95% CI 0.37–0.86)], dark fish and shellfish-meat (p < 0.0001), EPA (p = 0.03) and DHA (p = 0.04). Three studies investigating fish consumption and PC-mortality identified a significantly reduced risk. Multivariate-OR (95% CI) were 0.9 (0.6–1.7), 0.12 (0.05–0.32) and 0.52 (0.30–0.91) at highest fish intakes.

The authors concluded that fish and fish-oil do not show consistent roles in reducing PC incidence, aggressiveness and mortality. Results suggest that the specific fish type and the fish-oil ratio must be considered. Findings suggest the need for large intervention randomised placebo-controlled trials.

Several other recent reviews have also generated encouraging evidence, e.g.:

Available evidence is suggestive, but currently inadequate, to support the hypothesis that n-3 PUFAs protect against skin malignancy.

…omega-3 fatty acids may exert their anticancer actions by influencing multiple targets implicated in various stages of cancer development, including cell proliferation, cell survival, angiogenesis, inflammation, metastasis and epigenetic abnormalities that are crucial to the onset and progression of cancer.

If I was aiming for a career as a cancer quack, I would now use this evidence to promote my very own cancer prevention and treatment diet. As I have no such ambitions, I should tell you that regular fish oil consumption is no way to treat cancer. It also is no way to prevent cancer. If anything, it might turn out to be a way of slightly reducing the risk of certain cancers. To be sure, we need a lot more research, and once we have it, fish oil will be entirely mainstream. Raising false hopes regarding ‘alternative cancer cures’ based on fairly preliminary evidence is counter-productive, unethical and irresponsible.

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]

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