Evidence Based Medicine (EBM) seeks to use the best available evidence in making sound clinical decisions while caring for patients. It seeks to integrate clinical judgment on the part of the physician, the best clinical evidence obtained through robust scientific research methodology, and the patient's values and preference. This is clearly a desirable aim that would benefit patients. This is because physicians with years of experience generally have developed clinical judgment and expertise that enables them to make sound diagnoses while also factoring in any special circumstances and preferences of their patients and their caregivers when developing a patient care plan. External clinical evidence has the positive potential to replace old diagnostic tests and/or treatments with newer tests or treatments that are more effective or may have less deleterious side effects. It is clear that a physician who does not incorporate currently available best evidence risks having a practice that is out of date. So it is fair to say that the goal of EBM is a good one but it is at this point difficulties arise in clearly defining what constitutes EBM.EBM seeks to use “evidence” in the practice of medicine. According to this approach, RCTs or the systematic review of many randomized trials offer better evidence than can be obtained from say, observational studies. To understand the basis of this belief we need to look a bit more closely at what a RCT seeks to achieve. The use of a control is an element that imparts validity to RCTs. Such a control is a means of ensuring that only one factor is being tested at a time and there aren’t any other variables at work that could introduce a bias of some sort and impact results. Additionally, by including a placebo comparison RCTs may attempt to blind participants, intervention providers and other trial stakeholders such as statisticians. RCTs that do not employ control group are also available, such as a comparative effectiveness trial. Hence randomization is not necessarily accompanied by placebo comparison. It depends on whether the aim of the research is to investigate “net efficacy” or “overall effectiveness”.A RCT seeks to remove as many sources of bias as possible from the process hopefully ensuring that no false conclusions are drawn from the experiment. In its essence, a RCT tries to find out if a proposed therapy actually makes a positive difference to the people receiving it. It seeks to do so by using a control group of patients that do not receive the new therapy and instead receive a placebo. This forms the baseline with the aim being to show that patients that do receive the new therapy do better than the control group. In a well performed RCT both groups of patients are randomized, i.e. the researcher does not get to choose who ends up in each group. These RCTs are double-blind in the sense that patients do not know which group they belong to, i.e. do not know they are getting the new therapy or a placebo, nor does the researcher know which patient is getting the new therapy or the placebo. Because RCTs eliminate bias through the use of double-blinding and help eliminate, or at least minimize, confounding factors through randomization, EBM claims that RCTs are the gold standard of evidence. The hope and expectation here is that RCTs will help physicians make better and more informed decisions.I believe that a physician's clinical expertise cannot be replaced by evidence provided by a RCT. It is the physician who decides, based on his or her expertise, whether the evidence provided by RCT applies to the patient and if so, how much. My biggest concern with RCTs has to do with ethical challenges. We know that RCTs involve a randomized control group that does not receive the new therapy while the other randomized group receives new therapy. While this may seem not to pose any significant ethical issue when investigators are trying to determine the efficacy of say a new blood pressure drug, when a RCT requires withholding lifesaving therapy from patients who would likely die without such therapy, that's when ethical concerns become significant. John Worrall cites the same concern in his paper Evidence and Ethics in Medicine while discussing a randomized study involving the use of extracorporeal membrane oxygenation (ECMO) in the treatment of pulmonary hypertension in newborns. This study required withholding this treatment from a control group of babies and instead treating them with them conventional treatments previously known to be ineffective. Based on their previous successful experience with using ECMO it was already known to the physicians conducting the randomized study that ECMO was a vastly superior treatment for pulmonary hypertension. Thus it was already known that the babies assigned to the control group, even if randomly selected, were likely to die. This poses strong ethical concerns in the use of RCTs in certain cases. Many of these cases involve potentially fatal conditions or those cases requiring surgery or those that can’t wait for trials be conducted.As Worrall goes on to successfully argue, the claim that only RCTs can provide objective scientific evidence on the success, or lack thereof, of a therapy is questionable. He points out that no RCT has ever been performed on appendectomy as a treatment for acute appendicitis, or aortic aneurysm repair, or any major surgical intervention. Can one argue with this? Just because there is no evidence one cannot necessarily assume that there is no effect. Howick in makes the argument that because RCTs rule out more confounding factors than observational studies in general RCTs provide superior evidential support than that from observational studies. However, even Howick, an outspoken proponent of EBM, goes on to concede that there is “the paradox that our most effective treatments, ranging from the Heimlich maneuver to external defibrillation, appear to be less well supported by evidence than many of our treatments with much smaller effects since their effects have never been tested in randomized trials on any description.” Clearly, it would be quite absurd and unethical to conduct RCTs on something like appendectomy or the Heimlich maneuver. Thus, even on Howick's view there are cases in which RCTs do not need to be (and indeed should not be) conducted. The difference is that Howick does not see this as a criticism of EBM in the way that Worrall does. Howick just agrees with the fact that in instances when certain interventions show a consistent effect that is clearly sufficient in overcoming the combined effects of plausible confounders, the effects of these interventions can be supported even in the absence of RCTs.There are other issues pertaining to RCTs that also raise questions. It is fairly well-known that well conducted RCTs tend to be quite expensive to conduct. Pharmaceutical companies are likely to conduct RCTs when there is a good opportunity for profit or patents. Then what happens to patients with other serious but rare conditions that do not involve substantial numbers of patients and hence limit profitability of pharmaceutical companies? In these cases RCTs may never be conducted.In closing I would like to say that RCTs are an important component of medical research and have helped improve the health of patients by replacing older and inefficient therapies with more effective ones. However, if no RCT has been carried out or is infeasible for a patient with a specific condition then physicians must use the next best external evidence that happens to be available such as well-designed observational studies.