Evidence-Based Medicine
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Evidence-Based Medicine
General Information
NEWS:
Cancer risk over building products “THE consumer watchdog has asked hardware stores to test imported building materials for the carcinogenic chemical formaldehyde. The Australian Competition and Consumer Commission has sought assurances from more than 100 importers of flat timber panels -- such as particle board, medium-density fibreboard and plywood -- that the products are safe. But the ACCC can do nothing to force importers and retailers to comply with voluntary Australian Standards for formaldehyde, which is used in wood glue. “
Gardeners warned over wood mould “Gardeners have been warned about a mould, called Aspergillus, that grows on compost and decaying wood following the death of a middle-aged man. He developed severe breathing problems after working with rotting wood and plant mulch in his garden. Medical journal The Lancet reported that the man, aged 47, died despite hospital anti-fungal treatment. An expert said a dust-mask was a good idea when moving large quantities of mouldy bark chippings or compost. The Aspergillus mould is very common in UK gardens and is better known as an allergy trigger, but serious illness linked to it remains relatively rare. “
Long-Term Pesticide Exposure May Increase Risk of Diabetes
Report: Polluted Air Puts Millions at Risk “After Los Angeles, cities with the worst year-round particle pollution included: • Pittsburgh • Bakersfield, Calif. • Birmingham, Ala. • Visalia-Porterville, Calif. • Atlanta • Cincinnati After Los Angeles, cities with the worst ozone pollution included: • Bakersfield, Calif. • Visalia-Porterville, Calif. • Houston • Fresno, Calif. • Sacramento, Calif. • Dallas/Ft. Worth • New York/Newark, N.J. “
Searching for Clarity: A Primer on Medical Studies “Experts agree that there are three basic principles that underlie the search for medical truth and the use of clinical trials to obtain it. The first, says Dr. Steven Goodman, an epidemiologist and biostatistician at Johns Hopkins University School of Medicine, is that it is important to compare like with like. The groups you are comparing must be the same except for one factor — the one you are studying. For example, you should compare beta carotene users with people who are exactly like the beta carotene users except that they don’t take the supplement. By contrast, observational studies that ask what happens to people who act a certain way in their everyday lives rather than in an experiment are not as tightly controlled. For example, if people who eat fruits and vegetables or take beta carotene are compared with those who don’t, the two groups are quite likely to be different from the start. Fruit and vegetable eaters and vitamin takers tend to be more health-conscious in general, more likely to exercise, less likely to smoke. So scientists try to adjust for these differences with statistical modeling.”
Treatment Bias Can Skew Results of Observational Studies
ARTICLES:
A Reader and Author Respond to "Why Is Evidence-Based Medicine the Legal Standard of Practice?"
Developing the evidence for evidence-based practice “In this issue of CMAJ, Deshauer and colleagues1 note that most (93%) trials of drugs for the treatment of depression last less than 6 months (typically 6–8 weeks); indeed, most are conducted for registration purposes by industry. Despite the widely accepted view that depression is chronic or recurrent, longer-term efficacy and effectiveness studies are few and far between. Thus, when asked by patients about the pros and cons of longer-term treatment, we have little evidence with which to respond. Clinical trials are complex, costly and time consuming. They can be roughly divided into "efficacy" trials and "effectiveness" trials. The former are usually designed to have the highest internal validity, thereby ensuring that differences between treatment groups are entirely attributable to the study treatments (e.g., drug v. placebo). These trials typically look for a signal that the treatment is better than placebo and establish safety and tolerability. Effectiveness trials (sometimes called practical or management trials) are more inclusive of patient groups and often use treatment conducted in routine practices rather than research-guided treatment methods. They often aim to define how the treatment performs in usual practice conditions, but these trials may also define how, for whom, when or in what setting a treatment is to be recommended. Effectiveness trials include a broad assessment of effectiveness, including outcomes such as daily function, quality of life and health care utilization, whereas efficacy trials typically focus on symptoms. … Defining how, when, for whom and in what settings available treatments are best, and how safe and effective new treatments are in representative practice (T2 research) cannot be the sole responsibility of industry. Why not? Because such research will potentially limit the use of a new drug or create data for counter-marketing by competitors. Companies logically want to control study designs to protect their products. Who can blame them? Indeed, even if these studies are well designed and executed, doubt may remain about the findings, given the source of funding. Independent sources of funding (e.g., government and foundations) are needed if we are serious about putting real evidence into evidence-based medicine. Definitive, generalizable studies that involve "real world" patients given treatment under clinically feasible conditions and that use both registries and randomization are needed to better inform us about patient safety, provide evidence for clinical decision-making and improve outcomes. Without such studies, clinical decision-making will remain the art of medicine rather than the science it should be. “
Evidence-based common sense? “Evidence-based medicine (EBM) is the popular term, all too loosely used, to validate claims made by various health practitioners, educators, authors, researchers, and pharmaceutical company representatives about the benefits and limitations of drug use and clinical management of disease. According to Marchevsky’s Critical Appraisal of Medical Literature, EBM aims to "de-emphasize intuition, unsystematic clinical experience, and pathophysiological rationale as sufficient grounds for clinical decision making."1 Certainly, if all research were truly randomized, blinded, and free from any bias, then such a rigorous, scientific approach might offer a reliable source of clinical advancement. The reality, however, is that bias, competing interests, and misinterpretation (or manipulation) of data are all rampant in our medical literature and continuing medical education. It is thus the important responsibility of the clinician reader to interpret such medical literature with a discerning eye, a healthy scepticism, and both feet firmly grounded in their own common-sense intelligence. … Does chronically reducing stomach acid, or even treating H pylori infections with antacids, make sense? The question must arise—have the "evidenced-based" recommendations for PPIs really proven themselves to be best practice? … Examples of common sense being forsaken in clinical practice abound. … Evidence-based medicine and the research that supports it are essential aspects of determining best clinical practice as our medicine continues to change and evolve. And yet our experience has shown that EBM is not sufficient in and of itself. We do not live or practise in a laboratory, nor within the boundaries of double-blind, placebo-controlled trials. We live in a real world with patients who are also people. We are the inheritors of traditions and histories in medicine from which we should have grown and learned. Placebo effects, human bias, research politics, competing interests, and subjective interpretation are plain realities of any research and can easily blur definitive conclusions.”
Is an Evidence-Based Approach to Creating Guidelines Always the Right one? “When evidence is of high quality, strong recommendations are sometimes possible; however, even in the presence of high-quality evidence, recommendations will be weak if benefits and risks are closely balanced between competing interventions. In such instances, the role of relative values and preferences becomes predominant and it is important to make these explicit. There are pitfalls for the unwary. One must be aware of the limitations that might compromise desirable outcomes when reviewing evidence-based guidelines. In some instances, experts creating guidelines do not clearly define their question, in particular by failing to make the outcome(s) of interest explicit. They might also fail to conduct systematic reviews of the literature and, therefore, use biased estimates of treatment effect as the basis for their recommendations. These experts might also fail to consider the quality of the primary studies, including basic and detailed study design, and therefore further the likelihood of publication bias. Moreover, experts do not always make the values and preferences that underlie their recommendations explicit, and substitute their own values and preferences for those of their patients. … The current proliferation and duplication of guidelines is wasteful[8] and, ideally, each specialty group should produce a central repository of evidence that is regularly updated. For each disease, a central evidence base could be built from the available systematic reviews. From this central resource, regional guidelines could be developed, taking account of local resources and expertise and the values and preferences important in that population. The initiative of the US National Guidelines Clearing House to develop syntheses of guidelines that cover similar topics can perhaps be seen as a sensible first step in this direction.[9]“
Scepticism regarding common sense “While I agree that considerable scepticism is required in the interpretation of EBM and the clinical trials upon which it is based, I submit that common sense requires at least as much scepticism in its implementation. … I further assert that any intervention, complementary and alternative medicine or otherwise, that has not been proven effective in a well-designed trial remains in the same category as over zealous phlebotomy and hormone replacement therapy. That is not to say it cannot possibly be effective, but we must also consider the possibility that its use might be based entirely on the impression of a pattern that isn’t really there, just like a shape perceived in the clouds.”
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