Hormone replacement therapy (HRT) for post-menopausal women was thought to decrease the chance of cardiovascular problems like heart attack and stroke. This ‘made sense’ because the risk of cardiovascular disease in women rose sharply after menopause, indicating that female hormones had a protective effect. Many large observational studies supported this belief, and HRT was widely prescribed in the 1980s and 1990s. Later evidence from large, placebo controlled, randomised trials failed to show any cardiovascular benefit. Again, observational evidence was shown to overestimate the effectiveness of a common medical treatment and again, practice became established before the definitive trials were done.
Sunday, 26 October 2014
Sunday, 19 October 2014
The most recent casualty of the sham surgery trial, adding to the list of operations that looked good and had good results until put to the leased biased test, is a procedure called renal denervation (cutting the nerves to the kidney). Years of good results showing that this procedure lowered blood pressure are now met with a blinded sham-controlled trial that showed no significant benefit over placebo.
Thursday, 18 September 2014
One of the fundamental principles of science is that the results of any experiment should be reproducible. Reproducibility is essential because it means that the results can be relied upon, as they are more likely to be true. Unfortunately, there is little fame in replicating someone else’s study; it is also hard to get such studies funded (because they are not ‘novel’). Consequently, many studies are not repeated and many findings stand alone without verification from separate, independent researchers. This is a problem because often when studies are replicated, they fail to reproduce the original findings.
Wednesday, 10 September 2014
Patients should have a voice in medical policy and treatment. ‘Grass-roots’ groups of patients are more likely to have that voice heard and to effect change if they are organised and well funded. Patient advocacy groups can therefore be more effective if they accept industry (pharma) funding. However, such groups can also serve the interests of the industry doing the funding. It is even better for the industry, however, if they organise the grass-roots patient advocacy group from the start; so-called ‘astroturfing’.
Sunday, 17 August 2014
In the 1940s and 50s (tapering into the 70s and 80s) tens of thousands of prefrontal lobotomies (severing the front part of the brain) were performed in Europe and North America for many types of mental conditions. It was done because doctors at that time believed that it worked, and they didn’t have many effective alternatives. However, it didn’t work, it made people worse and it even killed a few, despite a Nobel prize being awarded to one of the developers of the procedure.
Monday, 11 August 2014
This story is about a procedure that made sense and had supporting evidence, became common practice, but was later discontinued because a high quality study showed it to be ineffective. The story of extra-cranial intra-cranial bypass surgery ticks all the boxes: overestimation of benefit, seduction by the theory, unrecognised bias in studies, and just plain ineffectiveness despite our best effort and beliefs.
Friday, 27 June 2014
Wouldn’t it be great if there was a cheap, non-proprietary, readily available treatment for patients with heart attacks (acute myocardial infarction - AMI)? That’s what doctors wanted to believe, so when they saw the early results of magnesium therapy, they did exactly that. Magnesium therapy for AMI has been labelled a “lesson in medical humility”, but I see it as another example of the pervasive bias amongst researchers, doctors and the public that leads them to overestimate the effectiveness of medical therapies. Put simply, it was another case of ‘believing is seeing’.
Sunday, 22 June 2014
The idea is that experiments are first performed in the lab, are then performed in animals, and these experiments inform the eventual human studies. As a (seemingly) necessary step in this chain, animal experiments are (rightly or wrongly) tolerated based on their eventual benefit to humans. Animal studies however, are not good predictors of human trials, often do not inform human trials, and are methodologically inferior to human trials, so much so, that the results from animal studies are unreliable and biased. In other words, animal studies are often of no benefit to humans. Arguably, they do not benefit humans at all, let alone enough to justify their use. We either need to fix the problem or get out of the animal research game.
Sunday, 27 April 2014
When you raise your arm, the top of your humerus, where the rotator cuff tendons attach, “impinge” against your acromion. When this hurts, it is called impingement syndrome. “Decompressing” the joint by taking some bone off the acromion (an "acromioplasty”) makes sense, and seems to work well. The operation has been around for a long time, and there have been many studies looking at different ways of doing this operation, but very few studies looking at whether or not it works better than not operating. Interestingly, all of the studies that have been done conclude that this operation adds nothing.
Friday, 25 April 2014
Title: Testing Treatments 2nd Ed, 2011
Authors: Imogen Evans, Hazel Thornton, Iain Chalmers, Paul Glasziou
Publisher: Pinter and Martin, London
Testing Treatments is a book, and Testing Treatments Interactive (http://www.testingtreatments.org/) is a website that contains the book, with live links and added information. It is a valuable reference tool for the layperson and also useful for health practitioners who are not well versed in evidence-based medicine. The book tells you why it is important to test treatments, how this type of testing should be done, and how to make research better and more useful to future patients.
Sunday, 16 March 2014
What if I could produce an experiment that concluded that listening to an old song could make you younger? Not feel younger, but be younger. Impossible, of course, but the story of how this can be achieved is a great example of how easy it is to produce statistically significant findings in science. All you need is enough 'wriggle room' in the data and a pre-conceived notion of what the results will be. Like ghosts in The Sixth Sense, scientists often only see what they want to see.
Monday, 10 March 2014
As a junior doctor in Australia, the country with the deadliest snakes and spiders in the world, you quickly learn where the antivenoms are kept. Now it appears that the deadliness of these critters is less than we thought, and the benefits of the anti-venoms are under question, or have been proven to be ineffective.
Sunday, 23 February 2014
When treatment choices are limited or when true effectiveness is not clear, patients want hope: they want to have a chance to get better. Doctors hold this valuable commodity, and dispense it on demand, for a fee, after which they claim any perceived improvement as being due to their efforts. Even when a treatment is not proven to be effective, or when it is proven to be no better than placebo, doctors too easily fall into the role of hope-peddler, without considering the hidden costs or unintended consequences.
Friday, 24 January 2014
Allow me to make an assertion: breast cancer survival is not influenced by surgical excision of the primary tumour. This goes against the prevailing wisdom that cancer is cured by removing it, but that kind of thinking is simplistic and at odds with much of the evidence. Lets walk through that evidence.
Thursday, 2 January 2014
I have previously written that knee arthroscopy for osteoarthritis is no more effective than alternatives, including placebo. One criticism of those studies was that arthroscopy is usually done for a torn meniscus (often incorrectly called a torn cartilage) rather than arthritis, despite the facts that the original sham trial of arthroscopy included patients with meniscus tears, and later comparative studies looked specifically at patients with torn menisci. Now, however, we have evidence from a placebo-controlled trial of arthroscopic surgery performed specifically for a torn meniscus in patients without arthritis. Evidence that shows that while most patients improve after surgery, they improve equally well after placebo surgery.
Friday, 20 December 2013
In the early days of surgery, surgeons tried to out do each other in their ability to perform bigger operations, and mastectomy was no exception. For breast cancer, excising the tumour seemed like logical treatment, at least for local control. It also seemed logical that if some excision was good, more excision was better. So simple tumour excision soon gave way to simple mastectomy, which gave way to total mastectomy, which gave way to radical mastectomy, which gave way to things like the ‘extended’ radical mastectomy and the ‘supra-radical’ mastectomy (which included excising the chest wall, amongst other things). Yet, all of this effort was done without properly evaluating the effectiveness – it was all based on what seemed like a good idea.
Friday, 29 November 2013
Title: The Doctor’s Guide to Critical Appraisal, 3rd Ed (2012)
Authors: Narinder Gossall, Gurpal Gossall
This book is not an opinion piece and it holds no new information, but it is as important as any other book I have reviewed because it aims to narrow the gap between practice and evidence in medicine by teaching doctors the science of medical practice; in other words, how to recognise and weigh error, and objectively appraise the scientific evidence for clinical practice.
Monday, 18 November 2013
Sunday, 10 November 2013
It seems I will never run out of examples of treatments that sound obviously effective in theory, fall into common use based on the strength of the biological mechanism, and yet they fail to show a significant benefit when put to the test. The story of the IVC filter is one of these.
Deep venous thrombosis (DVTs, clots) in the leg can dislodge, traveling up through the main vein in the pelvis and abdomen (inferior vena cava, IVC), through the heart and then embolise in the lungs (pulmonary embolus, PE), sometimes causing rapid death. An IVC filter is a wire cage placed in the IVC that snares clots that have broken free from the leg veins, before they can travel to the lungs. The device has been used for decades, but without much evidence of benefit, as this recent report tells us.
Thursday, 31 October 2013
One of the most popular drugs prescribed these days are the bisphosphonates. You may know them as Fosamax (alendronate) or Actonel (risendronate). They have been pitched as the drug that everyone with osteoporosis should take, and if you are a female over 50, you may have been advised to get your bone density measured, in case you need to take these drugs. Worldwide sales of Fosamax alone hit the $3 billion mark before it went off patent in 2008. We know the drugs increase bone density, but that is just cosmetic surgery for the bones. How much of that translates into fracture prevention? And how many people would want to take this drug if they were given an accurate description of the risks and benefits?