EMS World

MAR 2013

EMS World Magazine is the most authoritative source in the world for clinical and educational material designed to improve the delivery of prehospital emergency medical care.

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EMS RESEARCH For example, you might note that applying a bandage seems to control minor external bleeding. To use the scientific method, you might hypothesize that bandages do indeed control bleeding better than doing nothing at all. You could conduct a randomized control study to test your hypothesis by randomly assigning patients to the "bandage group" or to the "do nothing group." You could then measure the amount of bleeding in each group and compare your results. Although there might be some ethical issues with your study, this experiment would help you prove or disprove the value of bandaging. "A combination of research studies and research methods guides the decisions that are made." Furthermore, if your experiment was done properly, your results would hold up if the study was repeated, regardless of who conducted the experiment. That is the value of quality research. However, not all research can live up to these quality markers. Unfortunately, much of what we do still relies on the "best guess strategy," but as we progress, we rely more and more on research and, in particular, research studies. When making decisions based on evidence (especially patient care decisions), it is clearly best to obtain an opinion based on many studies and not just a single work. The key is to obtain an objective opinion. When more than one study points to the same conclusion, it is more likely to be free from opinion and bias. Many individual studies are clouded by bias, which occurs when research is influenced by prior inclinations, beliefs or prejudices. Bias influences a study when the outcomes are manipulated to fit an expected outcome instead of being measured objectively against the hypothesis. This can occur when researchers have a financial gain in a particular outcome, but more commonly it 60 MARCH 2013 | EMSWORLD.com occurs simply as a result of poor methods used to conduct the research. In the true scientific method, outcomes are not bent to conform to previously held notions, but are examined objectively and evaluated based solely on the facts. Valid research embraces this idea and uses methods designed to limit outside influences. Different methods of research are considered more valid than others. This is typically judged by how well they avoid potential bias and exclude the possibility of error. Consider the following strategies: PROSPECTIVE VERSUS RETROSPECTIVE Retrospective reviews look at events that have occurred in the past. Healthcare frequently uses retrospective reviews to look back at the outcome of therapies previously performed. In contrast, prospective studies are designed to look forward. Methods are designed to test therapies and outcomes that will occur in the future. Prospective studies are generally easier to control, as rules and regulations can be put in place to control errors and prevent bias. Retrospective studies cannot necessarily be controlled in such a way. Retrospective studies can certainly be considered valid, but a prospective method is generally considered more valid. RANDOMIZATION High-quality studies use randomization. In medicine, this type of study typically compares one therapy against another. Bias is controlled by randomly assigning a therapy to patients, as opposed to having predetermined groups. It also improves objectivity when analyzing outcomes. In high-quality studies, the researcher and the patients may not even know which therapy they are receiving. This process is called blinding. A research study can be either single-blinded (the researcher knows who gets what therapy) or double-blinded (neither the patient nor the researcher knows who gets what therapy). By blinding a study, it is very difficult to influence outcomes in any way, and the results are far more likely to be objective. CONTROL GROUPS The use of a control group helps to better evaluate outcomes fairly. In medicine, a control group is commonly a known or currently used therapy. In our previous bandaging study, we compared the bandaging group against a "do nothing" group. In that case, the "do nothing" group would be our control group. Including this group allows us not just to evaluate the outcome of bandaging, but also to compare those outcomes against a different strategy. This comparison adds weight and value to the analysis. STUDY GROUP SIMILARITY If a group of patients is being used to test a new treatment, it is important that subjects in that group have a certain degree of similarity. Let us say, for example, that we want to test a new airway device's impact on survival in trauma patients. We have designed and implemented a study to compare the use of the new device against a group of patients who received care without using the device. In our study, paramedics were allowed to choose the patients on whom they wanted to use the new device. When we look at our results, we find that the device group had a much higher mortality rate. At face, we could assume that this means the device did not work. However, as we analyze the results, we find that the group assigned to the new device was much sicker than the group that did not receive the device. Here, the paramedics just thought it would be better to use the new device only in the worst-off patients. Did more people die because of the device, or did more people die simply because they were hurt worse from the beginning? It is difficult to say—and therein lies the difficulty in comparing two vastly different groups. Consider also the challenges in comparing different age groups, different treatment protocols, or even different genders. No study can be completely free from bias, but as you have seen, certain methods help to minimize the impact of subjectivity. Because of the dynamic and often sensitive nature of medicine, a large variety of research is used to make conclusions on therapies and treatment. Ideally, system-

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