MD, PhD, FMedSci, FSB, FRCP, FRCPEd

causation

“Wer heilt hat recht”. Every German knows this saying and far too many believe it. Literally translated, it means THE ONE WHO HEALS IS RIGHT, and indicates that, in health care, the proof of efficacy of a treatment is self-evident: if a clinician administers a treatment and the patient improves, she was right in prescribing it and the treatment must have been efficacious. The only English saying which is vaguely similar (but rarely used for therapies) is THE PROOF OF THE PUDDING IS IN THE EATING, translated into a medical context: the proof of the treatment is in the clinical outcome.

The saying is German but the sentiment behind it is amazingly widespread across the world, particularly the alternative one. If I had a fiver for each time a German journalist has asked me to comment on this ‘argument’ I could probably invite all my readers for a beer in the pub. The notion seems to be irresistibly appealing and journalists, consumers, patients, politicians etc. fall for it like flies. It is popular foremost as a counter-argument against scientists’ objections to homeopathy and similar placebo-treatments. If the homeopath cured her patient, then she and her treatments are evidently fine!

It is time, I think, that I scrutinise the argument and refute it once and for all.

The very first thing to note is that placebos never cure a condition. They might alleviate symptoms, but cure? No!

The next issue relates to causality. The saying assumes that the sole reason for the clinical outcome is the treatment. Yet, if a patient’s symptoms improve, the reason might have been the prescribed treatment, but this is just one of a multitude of different options, e.g.:

  • the placebo-effect
  • the regression towards the mean
  • the natural history of the condition
  • the Hawthorne effect
  • the compassion of the clinician
  • other treatments that might have been administered in parallel

Often it is a complex mixture of these and possibly other phenomena that is responsible and, unless we run a proper clinical trial, we cannot even guess the relative importance of each factor. To claim in such a messy situation that the treatment given by the clinician was the cause of the improvement, is ridiculously simplistic and overtly wrong.

But that is precisely what the saying WER HEILT HAT RECHT does. It assumes a simple mono-causal relationship that never exists in clinical settings. And, annoyingly, it somewhat arrogantly dismisses any scientific evidence by implying that the anecdotal observation is so much more accurate and relevant.

The true monstrosity of the saying can be easily disclosed with a little thought experiment. Let’s assume the saying is correct and we adopt it as a major axiom in health care. This would have all sorts of terrible consequences. For instance, any pharmaceutical company would be allowed to produce colourful placebos and sell them for a premium; they would only need to show that some patients do experience some relief after taking it. THE ONE WHO HEALS IS RIGHT!

The saying is a dangerously misleading platitude. That it happens to be German and that the Germans remain so frightfully fond of it disturbs me. That the notion, in one way or another, is deeply ingrained in the mind of charlatans across the world is worrying but hardly surprising – after all, it is said to have been coined by Samuel Hahnemann.

If one spends a lot of time, as I presently do, sorting out old files, books, journals etc., one is bound to come across plenty of weird and unusual things. I for one, am slow at making progress with this task, mainly because I often start reading the material that is in front of me. It was one of those occasions that I had begun studying a book written by one of the more fanatic proponent of alternative medicine and stumbled over the term THE PROOF OF EXPERIENCE. It made me think, and I began to realise that the notion behind these four words is quite characteristic of the field of alternative health care.

When I studied medicine, in the 1970s, we were told by our peers what to do, which treatments worked for which conditions and why. They had all the experience and we, by definition, had none. Experience seemed synonymous with proof. Nobody dared to doubt the word of ‘the boss’. We were educated, I now realise, in the age of EMINENCE-BASED MEDICINE.

All of this gradually changed when the concepts of EVIDENCE-BASED MEDICINE became appreciated and generally adopted by responsible health care professionals. If now the woman or man on top of the medical ‘pecking order’ claims something that is doubtful in view of the published evidence, it is possible (sometimes even desirable) to say so – no matter how junior the doubter happened to be. As a result, medicine has thus changed for ever: progress is no longer made funeral by funeral [of the bosses] but new evidence is much more swiftly translated into clinical practice.

Don’t get me wrong, EVIDENCE-BASED MEDICINE does not does not imply disrespect EXPERIENCE; it merely takes it for what it is. And when EVIDENCE and EXPERIENCE fail to agree with each other, we have to take a deep breath, think hard and try to do something about it. Depending on the specific situation, this might involve further study or at least an acknowledgement of a degree of uncertainty. The tension between EXPERIENCE and EVIDENCE often is the impetus for making progress. The winner in this often complex story is the patient: she will receive a therapy which, according to the best available EVIDENCE and careful consideration of the EXPERIENCE, is best for her.

NOT SO IN ALTERNATIVE MEDICINE!!! Here EXPERIENCE still trumps EVIDENCE any time, and there is no need for acknowledging uncertainty: EXPERIENCE = proof!!!

In case you think I am exaggerating, I recommend thumbing through a few books on the subject. As I already stated, I have done this quite a bit in recent months, and I can assure you that there is very little evidence in these volumes to suggest that data, research, science, etc.. matter a hoot. No critical thinking is required, as long as we have EXPERIENCE on our side!

‘THE PROOF OF EXPERIENCE’ is still a motto that seems to be everywhere in alternative medicine. In many ways, it seems to me, this motto symbolises much of what is wrong with alternative medicine and the mind-set of its proponents. Often, the EXPERIENCE is in sharp contrast to the EVIDENCE. But this little detail does not seem to irritate anyone. Apologists of alternative medicine stubbornly ignore such contradictions. In the rare case where they do comment at all, the gist of their response normally is that EXPERIENCE is much more relevant than EVIDENCE. After all, EXPERIENCE is based on hundreds of years and thousands of ‘real-life’ cases, while EVIDENCE is artificial and based on just a few patients.

As far as I can see, nobody in alternative medicine pays more than a lip service to the fact that EXPERIENCE can be [and often is] grossly misleading. Little or no acknowledgement exists of the fact that, in clinical routine, there are simply far too many factors that interfere with our memories, impressions, observations and conclusions. If a patient gets better after receiving a therapy, she might have improved for a dozen reasons which are unrelated to the treatment per se. And if a patient does not get better, she might not come back at all, and the practitioner’s memory will therefore fail register such events as therapeutic failures. Whatever EXPERIENCE is, in health care, it rarely constitutes proof!

The notion of THE PROOF OF EXPERIENCE, it thus turns out, is little more than self-serving, wishful thinking which characterises the backward attitude that seems to be so remarkably prevalent in alternative medicine. No tension between EXPERIENCE and EVIDENCE is noticeable because the EVIDENCE is being ignored; as a result, there is no progress. The looser is, of course, the patient: she will receive a treatment based on criteria which are less than reliable.

Isn’t it time to burry the fallacy of THE PROOF OF EXPERIENCE once and for all?

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,

concomitant treatments,

social desirability,

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.

Research is essential for progress, and research in alternative medicine is important for advancing alternative medicine, one would assume. But why then do I often feel that research in this area hinders progress? One of the reasons is, in my view, the continuous drip, drip, drip of misleading conclusions usually drawn from weak studies. I could provide thousands of examples; here is one recently published article chosen at random which seems as good as any other to make the point.

Researchers from the Department of Internal and Integrative Medicine, Faculty of Medicine, University of Duisburg-Essen, Germany set out to investigate associations of regular yoga practice with quality of life and mental health in patients with chronic diseases. Using a case-control study design, 186 patients with chronic diseases who had elected to regularly practice yoga were selected and compared to controls who had chosen to not regularly practice yoga. Patients were matched individually on gender, main diagnosis, education, and age. Patients’ quality of life, mental health, life satisfaction, and health satisfaction were also assessed. The analyses show that patients who regularly practiced yoga had a significantly better general health status, a higher physical functioning, and physical component score  on the SF-36 than those who did not.

The authors concluded that practicing yoga under naturalistic conditions seems to be associated with increased physical health but not mental health in chronically diseased patients.

Why do I find these conclusions misleading?

In alternative medicine, we have an irritating abundance of such correlative research. By definition, it does not allow us to make inferences about causation. Most (but by no means all) authors are therefore laudably careful when choosing their terminology. Certainly, the present article does not claim that regular yoga practice has caused increased physical health; it rightly speaks of “associations“. And surely, there is nothing wrong with that – or is there?

Perhaps, I will be accused of nit-picking, but I think the results are presented in a slightly misleading way, and the conclusions are not much better.

Why do the authors claim that patients who regularly practiced yoga had a significantly better general health status, a higher physical functioning, and physical component score  on the SF-36 than those who did not than those who did not? I know that the statement is strictly speaking correct, but why do they not write that “patients who had a significantly better general health status, a higher physical functioning, and physical component score  on the SF-36 were more likely to practice yoga regularly”? After all, this too is correct! And why does the conclusion not state that better physical health seems to be associated with a greater likelihood of practicing yoga?

The possibility that the association is the other way round deserves serious consideration, in my view. Is it not logical to assume that, if someone is  relatively fit and healthy, he/she is more likely to take up yoga (or table-tennis, sky-diving, pole dancing, etc.)?

It’s perhaps not a hugely important point, so I will not dwell on it – but, as the alternative medicine literature is full with such subtly  misleading statements, I don’t find it entirely irrelevant either.

Did I previously imply that osteopaths are not very research-active? Shame on me!

Here are two brand-new studies by osteopaths and they both seem to show that their treatments work.

Impressed?

Well, perhaps we better have a closer look at them before we start praising osteopathic research efforts.

THE FIRST STUDY

Researchers from the ‘European Institute for Evidence Based Osteopathic Medicine’ in Chieti, Italy, investigated the effect of  osteopathic manipulative therapy (OMT) on the length of hospital-stay (LOHS) in premature infants. They conducted an RCT on 110 preterm newborns admitted to a single specialised unit. Thus the subjects with a gestational age between 28 and 38 weeks were randomized to receive either just routine care, or routine care with OMT for the period of hospitalization. Endpoints were differences in LOHS and daily weight gain. The results showed a mean difference in LOHS between the OMT and the control group: -5.906 days (95% C.I. -7.944, -3.869; p<0.001). However, OMT was not associated with any change in daily weight gain.

The authors’ conclusion was bold: OMT may have an important role in the management of preterm infants hospitalization.

THE SECOND STUDY

The second investigation suggested similarly positive effects of OMT on LOHS in a different setting. Using a retrospective cohort study, US osteopaths wanted to determine whether there is a relationship between post-operative use of OMT and post-operative outcomes in gastrointestinal surgical patients, including time to flatus, clear liquid diet, and bowel movement [all indicators for the length of the post-operative ileus] as well as LOHS. They thus assessed the records of 55 patients who underwent a major gastrointestinal operation in a hospital that had been routinely offering OMT to its patients. The analyses showed that 17 patients had received post-operative OMT and 38 had not.The two groups were similar in terms of all variables the researchers managed to assess. The time to bowel movement and to clear liquid diet did not differ significantly between the groups. The mean time to flatus was 4.7 days in the non-OMT group and 3.1 days in the OMT group (P=.035). The mean post-operative hospital LOHS was also reduced significantly with OMT, from 11.5 days in the non-OMT group to 6.1 days in the OMT group (P=.006).

The authors concluded that OMT applied after a major gastrointestinal operation is associated with decreased time to flatus and decreased postoperative hospital LOHS.

WHAT SHOULD WE MAKE OF THESE RESULTS?

Some people may have assumed that OMT is for bad backs; these two studies imply, however, that it can do much more. If the findings are correct, they have considerable implications: shortening the time patients have to spend in hospital would not only decrease individual suffering, it would also save us all tons of money! But do these results hold water?

The devil’s advocate in me cannot help but being more than a little sceptical. I fail to see how OMT might shorten LOHS; it just does not seem plausible! Moreover, some of the results seem too good to be true. Could there be any alternative explanations for the observed findings?

The first study, I think, might merely demonstrate that more time spent handling  premature babies provides a powerful developmental stimulus. Therefore the infants are quicker ready to leave hospital compared to those children who did not receive this additional boost. But the effect might not at all be related to OMT per se; if, for instance, the parents had handled their children for the same amount of time, the outcome would probably have been quite similar, possibly even better.

The second study is not an RCT and therefore it tells us little about cause and effect. We might speculate, for instance, that those patients who elected to have OMT were more active, had lived healthier lives, adhered more rigorously to a pre-operative diet, or differed in other variables from those patients who chose not to bother with OMT. Again, the observed difference in the duration of the post-operative ileus and consequently the LOHS would be entirely unrelated to OMT.

I suggest therefore to treat these two studies with more than just a pinch of salt. Before hospitals all over the world start employing osteopaths right, left and centre in order to shorten their average LOHS, we might be well advised to plan and conduct a trial that avoids the pitfalls of the research so far. I would bet a fiver that, once we do a proper independent replication, we will find that both investigations did, in fact, generate false positive results.

My conclusion from all this is simple: RESEARCH CAN SOMETIMES BE MISLEADING, AND POOR QUALITY RESEARCH IS ALMOST INVARIABLY MISLEADING.

A recently published study by Danish researchers aimed at comparing the effectiveness of a patient education (PEP) programme with or without the added effect of chiropractic manual therapy (MT) to a minimal control intervention (MCI). Its results seem to indicate that chiropractic MT is effective. Is this the result chiropractors have been waiting for?

To answer this question, we need to look at the trial and its methodology in more detail.

A total of 118 patients with clinical and radiographic unilateral hip osteoarthritis (OA) were randomized into one of three groups: PEP, PEP+ MT or MCI. The PEP was taught by a physiotherapist in 5 sessions. The MT was delivered by a chiropractor in 12 sessions, and the MCI included a home stretching programme. The primary outcome measure was the self-reported pain severity on an 11-box numeric rating scale immediately following the 6-week intervention period. Patients were subsequently followed for one year.

The primary analyses included 111 patients. In the PEP+MT group, a statistically and clinically significant reduction in pain severity of 1.9 points was noted compared to the MCI of 1.90. The number needed to treat for PEP+MT was 3. No difference was found between the PEP and the MCI groups. At 12 months, the difference favouring PEP+MT was maintained.

The authors conclude that for primary care patients with osteoarthritis of the hip, a combined intervention of manual therapy and patient education was more effective than a minimal control intervention. Patient education alone was not superior to the minimal control intervention.

This is an interesting, pragmatic trial with a result suggesting that chiropractic MT in combination with PEP is effective in reducing the pain of hip OA. One could easily argue about the small sample size, the need for independent replication etc. However, my main concern is the fact that the findings can be interpreted in not just one but in at least two very different ways.

The obvious explanation would be that chiropractic MT is effective. I am sure that chiropractors would be delighted with this conclusion. But how sure can we be that it would reflect the truth?

I think an alternative explanation is just as (possibly more) plausible: the added time, attention and encouragement provided by the chiropractor (who must have been aware what was at stake and hence highly motivated) was the effective element in the MT-intervention, while the MT per se made little or no difference. The PEP+MT group had no less than 12 sessions with the chiropractor. We can assume that this additional care, compassion, empathy, time, encouragement etc. was a crucial factor in making these patients feel better and in convincing them to adhere more closely to the instructions of the PEP. I speculate that these factors were more important than the actual MT itself in determining the outcome.

In my view, such critical considerations regarding the trial methodology are much more than an exercise in splitting hair. They are important in at least two ways.

Firstly, they remind us that clinical trials, whenever possible, should be designed such that they allow only one interpretation of their results. This can sometimes be a problem with pragmatic trials of this nature. It would be wise, I think, to conduct pragmatic trials only of interventions which have previously been proven to work.  To the best of my knowledge, chiropractic MT as a treatment for hip OA does not belong to this category.

Secondly, it seems crucial to be aware of such methodological issues and to consider them carefully before research findings are translated into clinical practice. If not, we might end up with  therapeutic decisions (or guidelines) which are quite simply not warranted.

I would not be in the least surprised, if chiropractic interest groups were to use the current findings for promoting chiropractic in hip-OA. But what, if the MT per se was ineffective, while the additional care, compassion and encouragement was? In this case, we would not need to recruit (and pay for) chiropractors and put up with the considerable risks chiropractic treatments can entail; we would merely need to modify the PE programme such that patients are better motivated to adhere to it.

As it stands, the new study does not tell us much that is of any practical use. In my view, it is a pragmatic trial which cannot readily be translated into evidence-based practice. It might get interpreted as good news for chiropractic but, in fact, it is not.

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.

On this blog, we have repeatedly discussed the serious adverse effects of Spinal Manipulative Therapies (SMT) as frequently administered by chiropractors, osteopaths and physiotherapists. These events mostly relate to vascular accidents involving vertebral or carotid arterial dissections after SMT of the upper spine. Lower down, the spine is anatomically far less vulnerable which, however, does not mean that injuries in this region after SMT are impossible. They have been reported repeatedly but, to the best of my knowledge, there is no up-to-date review of such events – that is until recently.

Australian researchers have just filled this gap by publishing a systematic review aimed at systematically reviewing all reports of serious adverse events following lumbo-pelvic SMT. They conducted electronic searches in MEDLINE, EMBASE, CINAHL, and The Cochrane Library up to January 12, 2012. Article-selection was performed by two independent reviewers using predefined criteria. Cases were included involving individuals 18 years or older who experienced a serious adverse event following SMT applied to the lumbar spine or pelvis by any type of provider (chiropractic, medical, physical therapy, osteopathic, layperson). A serious adverse event was defined as an untoward occurrence that resulted in death or was life threatening, required hospital admission, or resulted in significant or permanent disability. Reports published in English, German, Dutch, and Swedish were included.

The searches identified a total of 2046 papers, and 41 articles reporting a total of 77 cases were included in the review. Important case details were frequently missing in these reports, such as descriptions of SMT technique, the pre-SMT presentation of the patient, the specific details of the adverse event, time from SMT to the adverse event, factors contributing to the adverse event, and clinical outcome.

The 77 adverse events consisted of cauda equina syndrome (29 cases); lumbar disk herniation (23 cases); fracture (7 cases); haematoma or haemorrhagic cyst (6 cases); and12 cases of neurologic or vascular compromise, soft tissue trauma, muscle abscess formation, disrupted fracture healing, and oesophageal rupture.

The authors’ conclusion was that this systematic review describes case details from published articles that describe serious adverse events that have been reported to occur following SMT of the lumbo-pelvic region. The anecdotal nature of these cases does not allow for causal inferences between SMT and the events identified in this review.

This review is timely and sound. Yet several factors need consideration:

1) The search strategy was thorough but it is unlikely that all relevant articles were retrieved because these papers are often well-hidden in obscure and not electronically listed journals.

2) It is laudable that the authors included languages other than English but it would have been preferable to impose no language restrictions at all.

3) Under-reporting of adverse events is a huge problem, and it is anyone’s guess how large it really is [we have shown that, in our research it was precisely 100%]

4) This means that the 77 cases, which seem like a minute number, could in reality be 770 or 7700 or 77000; nobody can tell.

Cauda equina (horse tail) syndrome was the most frequent and most serious adverse event reported. This condition is caused by nerve injury at the lower end of the spinal canal. Symptoms can include leg pain along the sciatic nerve, severe back pain, altered or loss of sensation over the area around the genitals, anus and inner thighs as well as urine retention or incontinence and faecal incontinence. The condition must be treated as an emergency and usually requires surgical decompression of the injured nerves.

Disk herniation, the second most frequent adverse event, is an interesting complication of SMT. Most therapists using SMT would probably claim (no, I have no reference for that speculation!) that they can effectively treat herniated disks with SMT. The evidence for this claim is, as far as I know, non-existent. In view of the fact that SMT can actually cause a disk to herniate, I wonder whether SMT should not be contra-indicated for this condition. I am sure there will be some discussion about this question following this post.

The authors make a strong point about the fact that case reports never allow causal inference. One can only agree with this notion. However, the precautionary principle in medicine also means that, if case reports provide reasonable suspicion that an intervention might led to adverse-effects, we need to be careful and should warn patients of this possibility. It also means that it is up to the users of SMT to demonstrate beyond reasonable doubt that SMT is safe.

Neck pain is a common problem which is often far from easy to treat. Numerous therapies are being promoted but few are supported by good evidence. Could yoga be the solution?

The aim of a brand-new RCT was to evaluate the effectiveness of Iyengar yoga for chronic non-specific neck pain. Patients were randomly assigned to either yoga or exercise. The yoga group attended a 9-week yoga course, while the exercise group received a self-care manual on home-based exercises for neck pain. The primary outcome measure was neck pain. Secondary outcome measures included functional disability, pain at motion, health-related quality of life, cervical range of motion, proprioceptive acuity, and pressure pain threshold. Fifty-one patients participated in the study: yoga (n = 25), exercise (n = 26). At the end of the treatment phase, patients in the yoga group reported significantly less neck pain compared as well as less disability and better mental quality of life compared with the exercise group. Range of motion and proprioceptive acuity were improved and the pressure pain threshold was elevated in the yoga group.

The authors draw the following conclusion: “Yoga was more effective in relieving chronic nonspecific neck pain than a home-based exercise program. Yoga reduced neck pain intensity and disability and improved health-related quality of life. Moreover, yoga seems to influence the functional status of neck muscles, as indicated by improvement of physiological measures of neck pain.”

I’d love to agree with the authors and would be more than delighted, if an effective treatment for neck pain had been identified. Yoga is fairly safe and inexpensive; it promotes a generally healthy life-style, and is attractive to many patients; it has thus the potential to help thousands of suffering individuals. However, I fear that things might not be quite as rosy as the authors of this trial seem to believe.

The principle of an RCT essentially is that two groups of patients receive two different therapies and that any difference in outcome after the treatment phase is attributable to the therapy in question. Unfortunately, this is not the case here. One does not need to be an expert in critical thinking to realise that, in the present study, the positive outcome might be unrelated to yoga. For instance, it could be that the unsupervised home exercises were carried out wrongly and thus made the neck pain worse. In this case, the difference between the two treatment groups might not have been caused by yoga at all. A second possibility is that the yoga-group benefited not from the yoga itself but from the attention given to these patients which the exercise-group did not have. A third explanation could be that the yoga teachers were very kind to their patients, and that the patients returned their kindness by pretending to have less symptoms or exaggerating their improvements. In my view the most likely cause of the results seen in this study is a complex mixture of all the options just mentioned.

This study thus teaches us two valuable lessons: 1) whenever possible, RCTs should be designed such that a clear attribution of cause and effect is possible, once the results are on the table; 2) if cause and effect cannot be clearly defined, it is unwise to draw conclusions that are definite and have the potential to mislead the public.

In the UK, we have about 150000 practitioners of Spiritual Healing (SH). They treat all sorts of conditions claiming to channel ‘healing energy’ into the patient’s body which enables him/her to heal itself. The plausibility of SH is very close to zero and, despite numerous trials, its clinical effectiveness remains unproven. A new and, in my view, remarkable study of SH was aimed at investigating whether “SH could support patients with breast cancer”.

Spiritual Healing was provided by 4 healers registered with the National Federation of Spiritual Healers. Twelve patients with breast cancer undergoing long-term hormone treatment and experiencing its adverse-effects as onerous, self-referred themselves and were given ten weekly sessions of approximately 40 minutes each. Data collected included participant’s daily records, direct observations noted by the healers, the researcher’s field diary and a one-to-one semi-structured interview.

The alleged positive effects of SH included alleviation of the physical adverse-effects of their treatment, increased energy levels, enhanced well-being, emotional relaxation, and re-engagement with pre-cancer activities. Although one participant admitted considering a drug holiday prior to joining the study, none of the participants felt tempted to stop their hormonal treatments while receiving SH. The authors concluded that “these qualitative findings indicate that SH has the potential to support patients with breast cancer in the maintenance of their long-term orthodox treatments. Further research is needed to test SH as a cost-effective complementary therapy, for those undergoing long-term cancer treatments.”

As I already mentioned, I think this study is remarkable. Having done quite a bit of research into SH myself, I know how bizarre this intervention truly is. A typical treatment session might be with the patient lying on a couch in a relaxing atmosphere, often accompanied by soothing background music; the healer would talk gently but very little to enable the patient to be comfortable and relax; the SH itself might be performed by the healer moving his/her hands at a distance over the body of the patient; the healer would explain that this may cause the sensation of warmth as the ‘healing energy’ enters the body. Altogether, the experience is exotic to say the least.

It is therefore not surprising that SH generates a host of non-specific effects, including the most enormous placebo-response I have ever witnessed in any clinical trial which I have been involved in. I am mentioning this, of course, to point out that the above-noted effects are entirely compatible with those of placebo. As the study has no control group, there is no way of knowing what the effects of SH per se might have been. The fact that patients self-referred themselves to SH would only amplify this placebo-response. In the discussion of the paper, we find a further interesting pointer regarding patients’ prior experience with conventional health care professionals: “participants felt they were left to cope alone as their side-effects were trivialized.”  This seems to suggest that the group of patients were indeed highly selected and all had suffered badly from previous experiences of poorly administered heath care. Thus their expectations of SH were probably high which, in turn, would exaggerate the placebo-response even further.

All of these phenomena might well be fascinating and could provide ample material for relevant research. They deserve to be analysed carefully and discussed openly and critically. Unfortunately none of this happened in the present study. The authors do not even consider the possibility that the observed effects could be related to anything else than their SH. Their stated aim to investigate whether SH supports cancer patients is not even approached; the authors simply assume a cause-effect relationship without demonstrating one. I find this is more than just a missed opportunity; in my view, it is pseudo-science. And this is the reason why I find this study remarkable.

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