Gill Stannard

Thursday, October 23, 2008

Evidence based medicine update

My relationship with evidence based medicine (EBM) has always been ambivalent. It is a limited system of enquiry but I love it when it confirms my own holistic world view and get exasperated when it does not!

But jokes aside, EBM is an overused tool. While it is easy to be seduced by the world of medical science, when we create the mother of all scientific analysis it tends to replicate rather than eradicate the flaws of the system in the first place.

There are a number of issues with the “gold standard”, placebo controlled, double blinded trials when applying them to an individual system of treatment such as naturopathy. How much of the client’s improved wellbeing is being catalysed by the diet changes, herbs, other natural medicine or the type of consultation itself? Longer than the average GP style visits, that most natural therapists choose, have been accused of creating a placebo effect. Others suggest that it is talk therapy and the process of ‘witnessing’ or acknowledging the clients journey that is a potent healing tool in itself.

We say that as naturopaths we “treat the individual, not the disease”, so while there may be commonalities in prescribing, for a common condition as basic as constipation, there may be dozens of frequently prescribed herbs who’s mode of action varies beyond being a straight laxative. This is because the underlying condition itself may be viewed as having many different causes and not all originating in the bowel itself.

Herbs are a complex mixture of chemicals that vary when sourced in different growing conditions and locations. The herbs can be used in a variety of ways. For internal treatment alone there are alcohol or glycerine extracts, tablets, capsules, powders, teas and combinations within all the above form. These combinations of herbs themselves can potentially have a synergistic reaction, meaning the herb itself may work slightly or even massively differently to when it is used on its own. So with EBM there are many issues that arise from the style and substance of treatment.

Whenever any system of enquiry limits itself in such a way, it is potentially problematic. The Cochrane Collaboration for example, leads the field with systematic reviews of medical literature. Basically it takes all the published research on a certain medical treatment and includes for analysis only studies that meet its rigorous criteria. Then they crunch the numbers and conclude the validity or otherwise of a particular drug, herb, surgery or other method of treatment. If Cochrane doesn’t give the tick to the treatment, it is often deemed unsuitable, ineffective and at worst dangerous by those who take the service at face value. Most reviews of complementary medicines are stamped with Cochrane's “no evidence to inform current practice”. All this means was they couldn’t find enough medical trials to analyze the effectiveness of the treatment.

Unfortunately if there is a lack of literature on the subject, usually due to the vast majority of this kind of research being funded by pharmaceutical companies, Cochrane is unable to recommend the treatment.

A recent example can be found regarding programs for people with dementia that focuses on physical activity rather than drugs. This is a brilliantly low cost treatment in terms of the public health coffers but without obvious profit it is hard to fund pilot programs, then bigger trials and finally reproduce the trial another time to show the first one wasn’t a fluke.

There is insufficient evidence to determine the effectiveness of physical activity programs in managing or improving cognition, function, behaviour, depression, and mortality in people with dementia

Summary: Few trials examined these important outcomes. In addition, family caregiver outcomes and use of health care services were not reported in any of the included studies. There is some evidence that physical activity delays the onset of dementia in healthy older adults and slows down cognitive decline to prevent the onset of cognitive disability. Studies using animal models suggest that physical activity has the potential to attenuate the pathophysiology of dementia. Four trials met the inclusion criteria. However, only two trials were included in the analyses because the required data from the other two trials were not made available. Further well-designed research is required.
The Cochrane Collaboration

But while some members of the medical community are quick to use lack of evidence as a way to discredit complementary health treatment, it can be deafeningly silent on putting it’s love of EBM where its mouth is when it comes to short comings of its own medicines and treatments.

What if the studies used for meta-analysis were fundamentally flawed in the first place? This has been recently discovered to be the case in much of the breast cancer research conducted in vitro, for many years. Due to an initial identification error, cell line 435, used in at least 650 studies of metastatic breast cancer for over quarter of a century was the wrong cancer. In 2000 it was discovered that cell line 435 had the characteristics of melanoma, a skin cancer. It was not breast cancer after all.

The consequences of this mistake must have ramifications on all current breast cancer treatment. But more of a concern is the 8 years it has taken from the first researcher raising the alarm, to the claim being widely accepted in the research community.

In the past month there have been a number of EBM reviews of treatments that have swung against current medical practice. Perhaps the most damning is a Cochrane review of prenatal care. How many women going to their GP to have their pregnancy confirmed are being told that current best practice would recommend that they leave the practitioner's office as fast as possible and consult a midwife, not a doctor or obstetrician for the health of their unborn child and the best chance of a low intervention birth?

The Cochrane Review analysed 11 published trials, involving 12,276 women comparing midwife care to medical doctors. The evidence overwhelmingly supported Midwife care: it was associated with lower rates of both miscarriage and medical intervention as well as a greater likelihood of a vaginal delivery.

Midwife-led care was associated with several benefits for mothers and babies, and had no identified adverse effects. The main benefits were a reduced risk of losing a baby before 24 weeks. Also during labour, there was a reduced use of regional analgesia, with fewer episiotomies or instrumental births. Midwife-led care also increased the woman's chance of being cared for in labour by a midwife she had got to know. It also increased the chance of a spontaneous vaginal birth and initiation of breastfeeding. In addition, midwife-led care led to more women feeling they were in control during labour. There was no difference in risk of a mother losing her baby after 24 weeks. The review concluded that all women should be offered midwife-led models of care.

The current caesarian rate in Australia is 31%, close to a 1:3 of live births. It would be logical to conclude if every GP followed EBM best practice and recommended their client chose midwife based care, not only would more babies survive to 24 weeks but the cost of health care would be much lower.

A second clanger to be dropped by Cochrane this month is in regards to the effectiveness of St John’s Wort in the treatment of major depression. Herbalists have always known that good quality (and quality is the key for all herbal prescribing) St John’s Wort takes the edge of depression. Previously researchers grudgingly accepted it had some validity but only for mild depression. But the effectiveness of St John’s wort for treating mild to severe depression has finally shone through. Cochrane concluded that the herb is at least as good as antidepressant medication but without the nasty side effects.

Depression is characterized by depressed mood and/or loss of interest or pleasure in nearly all activities and a variety of other symptoms for periods longer than two weeks. Extracts of St. John's wort (botanical name Hypericum perforatum L.) are prescribed widely for the treatment of depression.

We have reviewed 29 studies in 5489 patients with depression that compared treatment with extracts of St. John's wort for 4 to 12 weeks with placebo treatment or standard antidepressants. The studies came from a variety of countries, tested several different St. John's wort extracts, and mostly included patients suffering from mild to moderately severe symptoms. Overall, the St. John's wort extracts tested in the trials were superior to placebo, similarly effective as standard antidepressants, and had fewer side effects than standard antidepressants. However, findings were more favourable to St. John's wort extracts in studies form German-speaking countries where these products have a long tradition and are often prescribed by physicians, while in studies from other countries St. John's wort extracts seemed less effective. This differences could be due to the inclusion of patients with slightly different types of depression, but it cannot be ruled out that some smaller studies from German-speaking countries were flawed and reported overoptimistic results.

Patients suffering from depressive symptoms who wish to use a St. John's wort product should consult a health professional. Using a St. John's wort extract might be justified, but important issues should be taken into account: St. John's wort products available on the market vary to a great extent. The results of this review apply only to the preparations tested in the studies included, and possibly to extracts with similar characteristics. Side effects of St. John's wort extracts are usually minor and uncommon. However, the effects of other drugs might be significantly compromised.
Cochrane Review: “St John's wort for major depression”, Linde K, Berner MM, Kriston L.

Beyond the scope of the Review were some of the actual issues with the commonly prescribed antidepressants.

As covered in a previous post, current evidence finds that common antidepressant drugs aren't very effective. In fact, the study reported in the link concludes, “Meta-analyses of antidepressant medications have reported only modest benefits over placebo treatment, and when unpublished trial data are included, the benefit falls below accepted criteria for clinical significance.“

A small study examining the effect of Paroxetine (a common SSRI) on sperm has just been published. Following earlier anecdotal evidence of men experiencing decreased fertility while taking SSRIs this study looked at sperm samples from healthy men before taking the drug and after four weeks of treatment. DNA abnormalities in the sperm rose from 13% before taking the medication to over 30% one month into the trial. This evidence suggests that this class of antidepressant has a significant negative effect on male fertility.

The use of SSRIs in adolescents has become increasingly controversial due to an apparent increase in suicides in young people taking these drugs. According the TGA: ” “None of the SSRIs, and indeed no antidepressant, is currently approved in Australia for the treatment of MDD (major depressive disorder) in children and adolescents (persons aged less than 18 years).”

Yet despite a long list of common side effects, let alone a worsening of symptoms or infertility, the vast majority of GPs and psychiatrists prescribe these drugs over an equally effective and less adversely reacting herb.

As a herbalist, I strongly suggest that you see both a qualified herbalist and registered psychologist for the treatment of depression. You may also be eligible for a Medicare rebate when seeing a psychologist in Australia.

EBM is an interesting tool. If your medical professionals subscribe to it, then you have a right to question their treatment in terms of current evidence.

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