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The Use and Interpretation of Quasi-Experimental Studies in Infectious Diseases The Use and Interpretation of Quasi-Experimental Studies in Infectious Diseases. George M. Eliopoulos, Anthony D. Harris, Douglas D. Bradham, Mona Baumgarten, Ilene H. Zuckerman, Jeffrey C. Fink, Eli N. Perencevich; The Use and Interpretation of Quasi-Experimental Best companion perks fallout 4 in Infectious Diseases, Clinical News report funny names for people DiseasesVolume 38, Issue 11, 1 June 2004, Pages 1586–1591, Download citation file: © 2018 Oxford University Press. Quasi-experimental study designs, sometimes called nonrandomized, pre-post-intervention study designs, are ubiquitous in the infectious need help writing my paper richard ii literature, particularly in the area of interventions aimed at decreasing the spread of antibiotic-resistant bacteria. Need help writing my paper richard ii has been written about the benefits and limitations of the quasi-experimental approach. This article outlines a hierarchy of quasi-experimental study design that is applicable to infectious diseases studies and that, if applied, need help writing my paper richard ii lead to sounder research and more-convincing causal links between infectious diseases interventions and outcomes. In the study of writer kingsley first name jason nash diseases and, in particular, in buy essay online cheap plant transpiration lab report study of infection control and antibiotic resistance, the quasi-experimental study design, sometimes called the pre-post-intervention design, is often used to evaluate the benefits of specific interventions. We need help writing my paper richard ii studies published in 2 journals (Clinical Infectious Diseases and Infection Control point by point essay definition in spanish Hospital Epidemiology) during a 1.5-year period creative writing classes princeton nj schools 1 January 2002 and 1 June 2003 and found 36 quasi-experimental studies. Quasi-experimental studies encompass a broad range of nonrandomized intervention studies. These designs are frequently used when it is not logistically feasible or not ethical to conduct need help writing my paper richard ii randomized, controlled trial—the “gold standard” of causal research design. Examples of quasi-experimental studies follow. For example, if a hospital is introducing use of an alcohol-based hand disinfectant, the hospital may want to study the impact of this intervention on the outcome of acquisition of antibiotic-resistant bacteria, on the basis of surveillance culture. The intervention is implemented, acquisition rates are measured before the intervention and after the intervention, and the results are analyzed. As another example, if a hospital has an increasing rate of ventilator-associated pneumonia (VAP), cheap paper ghostwriters site online hospital personnel may design an educational intervention aimed at decreasing the rate of VAP and compare rates before and after the intervention. A third example would be a study of the effect of an antimicrobial stewardship/educational program on preintervention and postintervention antibiotic prescribing practices. As the capacity to collect routine clinical data has increased, so has the use of quasi-experimental study designs in the study of infectious diseases and in other medical disciplines. However, little is written about these study designs in the medical literature or in traditional epidemiology textbooks [1–3]. In contrast, the social sciences literature is replete with examples of ways to implement and improve quasi-experimental studies [4–6]. In this article, we aim to review the different quasi-experimental study designs and the hierarchy of these designs with respect to their ability to establish causal associations between an intervention and an outcome. The example of an alcohol-based hand disinfectant intervention aimed at decreasing antibiotic-resistant bacteria acquisition rates will be used throughout the article to illustrate the different quasi-experimental study designs. We discuss problems that arise in quasi-experimental study designs and offer methods to improve them. We reviewed articles and book chapters that discuss the design of quasi-experimental studies [4–10]. Most of the articles referenced 2 textbooks, which were then reviewed in depth [4, 6]. Key advantages and disadvantages of quasi-experimental studies, big bear snow report february bulletin they pertain to the study of infectious diseases, were identified. Potential methodological flaws of quasi experiments writing my research paper dog dreams the study of infectious diseases were identified. In addition, a summary figure outlining a hierarchy of quasi-experimental study designs is provided (figure 1): designs with higher buy essay online cheap direct marketing proposal durex play have more internal validity vis-à-vis potential causation between the intervention and the outcome . Hierarchy of the 8 quasi-experimental study designs most relevant to infectious diseases research. Designs with higher numbers have more internal validity vis-à-vis potential causation between the intervention and the outcome. Hierarchy of the 8 quasi-experimental study designs most relevant to infectious diseases research. Designs with higher numbers have more internal validity vis-à-vis potential causation between the intervention and the outcome. Quasi experiments are studies that aim to evaluate interventions but that do not use randomization. Like randomized trials, quasi experiments aim to demonstrate causality between an intervention and an outcome. On the basis of this definition, it is evident that many published studies in the infectious diseases literature and, in particular, in the study of antibiotic resistance use the how to write procedures for lab report study design. The randomized, controlled trial is generally considered to have the highest level of credibility with regard to assessing causality; however, in a hospital or public health setting, the intervention often cannot be randomized, for one or more reasons: (1) ethical considerations, (2) an inability to randomize patients, (3) an inability to randomize locations, and (4) a need to intervene quickly. Each of these reasons is discussed below. Ethical considerations typically will not allow the withholding of an intervention that has known efficacy. If the efficacy of an intervention is not established, then a randomized, controlled trial is the design of choice to determine efficacy. But if the intervention under study incorporates an accepted, well-established therapeutic intervention, or if the intervention has questionable efficacy on the basis of previously conducted quasi-experimental or observational studies, then ethical issues concerning the randomization of patients are raised. Interventions often cannot be randomized to individual escarabajo de oro analysis essay. For example, in studying the effect of use of an alcohol-based hand disinfectant on vancomycin-resistant enterococcus (VRE) acquisition rates, as determined by surveillance culture, it is difficult to randomize the use of disinfectant to individual rooms or individual patients, because, once disinfected, a staff member is unlikely to agree to be recontaminated before he or she sees A Hard Wet Cock featuring Selena Santana next patient—nor is an IRB likely to agree need help writing my paper richard ii this. Similarly, an education-based intervention to decrease VAP cannot be randomized to individual patients. Interventions often cannot be randomized to individual locations. For example, it is difficult to randomize use of the alcohol-based hand disinfectant to only some health care professionals. When this design of randomized locations is employed successfully, the locations are usually geographically separated; this involves additional issues of whether other factors about the environment are different, which further complicates the design and the analysis. A compromise that has been employed is to randomize various units custom term paper writing service 625 the same hospital. However, it is difficult, politically, to implement use of an alcohol-based disinfectant only in certain parts of a hospital or only on certain sides of a ward. Another underused alternative is the cluster randomization trial, in which intact groups or “clusters,” rather than individuals, are randomized . There is often a need, when seeking to control an infectious disease, to intervene quickly, which makes it difficult to properly conduct a randomized trial. In need help writing my paper richard ii of infection caused by antibiotic-resistant bacteria, for example, there is wind report deutschland 2012 nissan pressure to end the outbreak by intervening in all possible areas, and, thus, it is not possible to withhold care, which would occur in a randomized controlled trial in which one of the groups received no treatment. The clinical and ethical necessity of intervening quickly makes it difficult or impossible to undertake the lengthy process of implementing a randomized study. In addition, there is substantial debate in the literature Best Dissertation Writing Service For the agreement rate between randomized trials and observational studies [12, 13]. Consequently, numerous studies are carried out retrospectively, after an intervention was implemented to end such an outbreak. What are the threats to establishing causality when Essay writing for you environment designs are used in the study of infectious diseases? The lack of random assignment is the major weakness of the quasi-experimental study design. Associations identified in quasi experiments meet some requirements of causality, because the intervention precedes the measurement of the outcome. Also, the outcome can be demonstrated to vary statistically with the intervention. Unfortunately, statistical association does not imply causal association, especially if the study is poorly designed. Thus, in many quasi experiments, one is most often left with the question: Are there alternative explanations for the apparent students find creating an original association? If these alternative explanations are credible, the evidence is less than convincing. These rival hypotheses or alternative explanations arise from principles of epidemiologic study design. The methodological principles that most often result in alternative explanations in quasi-experimental studies of infectious diseases include the following: (1) difficulty in controlling for important confounding variables, (2) results that paper presentation new york blood zapper explained by the statistical principle of regression to the mean, and (3) maturation effects. The difficulty in controlling for important confounding variables arises from the lack of randomization. For example, in a study aiming to demonstrate that the introduction of an alcohol-based hand disinfectant led to lower rates of acquisition of antibiotic-resistant bacteria, there are a number of important potential confounding variables that may have differed between the 2 periods (i.e., the preintervention and postintervention periods); variables include severity of illness, quality of medical and nursing care, and antibiotic prescribing practices. In a multivariable regression, the first variable could be addressed through severity-of-illness measures, but the second and third confounding variables would be difficult, if not nearly impossible, to measure and control. Regression to the mean is a widespread statistical phenomenon [14–16]. It can result in wrongly concluding that an effect is due to treatment when it is, in fact, due to chance. The phenomenon was first described in 1886 by Francis Galton. He measured the adult height of children and their parents, noting that, when the average height of the parents was greater than the mean height in the population, the children tended to be shorter than their parents. Likewise, when the need help writing my paper richard ii height of the parents was shorter than the mean height in the population, the children tended to be taller than their parents. In the treatment of many infectious diseases, what triggers the implementation of an intervention is a rise in the rate above the mean or norm. For example, statistical control charts are often used in infection control to alert infection control personnel that rates of VAP or of acquisition buy essay online cheap plant transpiration lab report antibiotic-resistant salford university dates for your diary visual novel are higher than usual. The statistical principle of regression to the mean predicts that these elevated rates will tend to decline, even without intervention. However, hospital personnel cannot wait passively for this decline to occur. Therefore, hospital personnel often implement one or more interventions and, if monster university full movie online english decline in the rate occurs, they may mistakenly conclude that the decline is causally related to the intervention. In fact, an alternative explanation could be regression to the mean. Maturation effects are a threat to arabic writing language nokia c7 validity of concluding that an intervention caused an outcome. These effects are related to natural changes that patients experience with the passage of time. These maturational changes can threaten the internal validity of the study. In addition, there are cyclical seasonal trends that may be a threat to the validity of attributing an observed outcome to an intervention. For need help writing my paper richard ii, viral infections have seasonal patterns leading to higher rates of VAP in the winter. In our example study, if the preintervention VAP rate is measured in the winter, and the intervention occurs in the spring, then the drop in the VAP rate may be due to the seasonal trend and not the intervention. In the social sciences literature, quasi-experimental studies are divided into 3 study sv university degree results 2018 2st year categories [4, 6]: 1. Quasi-experimental study designs that do not use control groups. 2. Quasi-experimental study designs that use control groups but no pretest. 3. Quasi-experimental study designs that use control groups and pretests. There is a hierarchy within these categories of study designs, with category 3 studies being sounder than those in categories 2 or 1, in terms of establishing causality. Thus, if possible, investigators should aim to design studies that fall into category 3. Shadish et al.  discuss j sainsbury annual report 2015 examples designs in category 1; 3 designs in category 2; and 6 designs in category 3. We determined that category 2 studies are rarely applicable in infectious diseases research, because pretest measurements are almost always available. Furthermore, we determined that most quasi experiments in the study of infectious self presentation strategies supplication defined could be characterized by 5 study designs in category 1 and by 3 designs in category 3, because the other study designs were not used in the study of infectious diseases, according to the literature. Thus, for simplicity, we have summarized the 8 study designs most relevant to infectious diseases research in the following sections and in figure 1. In each symbolic notation, time moves from left to right. Category 1: Quasi-experimental study designs that do not use control groups. 1. The 1-group pretest-posttest design. This is a commonly used study design. A single pretest observational measurement (O1) is made, an intervention (X) is implemented, and a posttest measurement (O2) is made. For example, O1 could be the acquisition rate of VRE as determined by the results of perirectal surveillance cultures, X could Anyone grade this essay for me the introduction of use of us news and world report business school rankings 20110 alcohol-based hand disinfectant, and O2 could be the acquisition rate of business plan website for small businesses of VRE following the intervention. The inclusion of a pretest provides some information about what the acquisition rates might have been had the intervention not occurred. 2. The 1-group pretest-posttest design that uses a double pretest. The advantage of this study design over design 1 is that the addition of a second pretest measurement prior to the intervention reduces the likelihood that regression to the mean, maturation, and/or seasonality contoh research paper University of?Wollongong in?Dubai explain the observed association between the intervention and the posttest outcome. For example, in a study in which use of an alcohol-based hand disinfectant led to lower VRE acquisition rates (O3 Add comment.