作者：Elizabeth Yuko；审核：Anju Goel；发布于2021年2月19日一项队列研究（Cohort study）通常观察两组或更多具有不同属性的人（例如一些人吸烟，一些人不吸烟），试图了解特定属性如何影响结果，了解一个群体的共同属性（在本例中是吸烟）与其最终结果之间的关系。队列研究设计循证医学研究分为两类：实验研究（Experimental research）：这涉及到一个受控的过程，临床试验中的每个参与者都暴露在某种干预或某种情况下，比如药物、疫苗或环境暴露。有时也有一个对照组，与不暴露的进行比较。分析在一段时间内跟踪暴露或干预的影响。观察研究（Observational research）：这是没有干预的情况，研究人员只是观察参与者在一段时间内的暴露情况和结果，试图找出可能影响各种健康状况的潜在因素。队列研究是纵向的，这意味着他们经常在一段时间内进行，每年定期检查参与者，记录他们的健康状况和健康行为等信息。它们可以是：前瞻性（Prospective）：从现在开始，持续到未来。回顾性（Retrospective）：从现在开始，回顾过去，了解医疗结果和事件的信息。队列研究的目的队列研究的目的是帮助提高医学知识和实践，例如更好地了解增加一个人患某种疾病几率的危险因素。队列研究的参与者被分组在一起是基于有一个共同的特征，比如来自相同的地理位置，或有相同的职业，或者有相同的医疗状况的诊断。每次研究人员对队列试验的参与者进行检查时，他们都能够测量参与者在一段时间内的健康行为和结果。例如，一项研究可能涉及两组人：一组吸烟，另一组不吸烟。随着数据收集的完善，研究人员将更好地了解吸烟行为与特定结果（例如肺癌）之间是否存在联系。队列研究的优势医学界目前对疾病危险因素的认识大多来自队列研究。除了显示疾病进展外，队列研究还帮助研究者计算发病率、累积发病率、相对风险和健康状况的危险比。规模（Size）：与小型研究相比，具有许多参与者的大型队列研究通常会给研究人员提供更有说服力的结论。时间轴（Timeline）：因为队列研究可以追踪疾病的进展，所以队列研究也有助于确定健康状况的时间轴，并确定特定行为是否是导致疾病的潜在因素。多重测量（Multiplemeasures）：通常队列研究允许研究人员观察和跟踪同一暴露的多种结果。例如，如果一个队列研究是跟踪一组接受化疗的人，研究人员可以研究病人恶心和皮疹的发生率。在这种情况下，有一个暴露因素（化疗）和多个结果（恶心和皮疹）。准确度（Accuracy）：队列研究的另一个优势，特别是前瞻性队列研究，是研究人员可以相对准确地测量暴露变量、其他变量和参与者的健康结果。一致性（Consistency）：队列研究测量的结果可以统一完成。回顾性队列研究有其自身的优点，即与其他类型的研究相比，它们可以相对快速、容易和低成本的进行。如何保护研究参与者队列研究的弱点虽然队列研究是医学研究的一个重要组成部分，但也有其局限性，其中包括：时间（Time）：研究人员并不是简单地把参与者带到实验室一天来回答几个问题。队列研究可以持续数年甚至数十年，这意味着进行研究的成本确实会增加。自我报告（Self-reporting）：尽管回顾性队列研究成本较低，但它们也有自己的显著缺点，即它们可能依赖于参与者对过去状况、结果和行为的自我报告，可能很难得到准确的结果。中途退出（Drop-out）：考虑到队列研究需要花费很长时间，参与者退出这类研究并不罕见。尽管他们完全有权这么做，但让太多人离开研究可能会增加产生偏差的风险。行为改变（Behavior alteration）：队列研究的另一个缺点是，如果参与者不是研究的一部分，他们可能会改变自己的行为方式，这可能会改变研究的结果。偏差的可能性（Potential for biases）：即使是设计最完善的队列研究也不会取得像随机对照试验那样可靠的结果。这是因为通过设计，人们根据某些共同的特征分成不同的组，这就缺乏内在的随机性。总结经过多年的研究和临床试验，药物、器械和其他治疗方法才能够上市。从在实验室里对一种药物的早期配方进行第一次测试，到在电视上看到它的商业广告以及一系列副作用的列表，有一段很长的路要走。想想你上次体检的时候，你的医生可能测量了你的一些生命体征，给你做了血液测试，然后向你报告了你可能需要改变的各种行为，以降低你患某些疾病的风险。这些危险因素不仅仅是猜测，其中许多是队列研究的结果。【原文】What Is a Cohort Study?By Elizabeth Yuko, PhD；Medically reviewed by Anju Goel, MD, MPHUpdated on February 19, 2021A cohort study often looks at 2 (or more) groups of people that have a different attribute (for example, some smoke and some don't) to try to understand how the specific attribute affects an outcome. The goal is to understand the relationship between one group's shared attribute (in this case, smoking) and its eventual outcome.Cohort Study DesignThere are two categories of evidence-based human medical research:Experimental research: This involves a controlled process through which each participant in a clinical trial is exposed to some type of intervention or situation—like a drug, vaccine, or environmental exposure. Sometimes there is also a control group that is not exposed for comparison. The results come from tracking the effects of the exposure or intervention over a set period of time.Observational research: This is when there is no intervention. The researchers simply observe the participants' exposure and outcomes over a set period of time in an attempt to identify potential factors that could affect a variety of health conditions.Cohort studies are longitudinal, meaning that they take place over a set period of time—frequently, years—with periodic check-ins with the participants to record information like their health status and health behaviors.They can be either:Prospective: Start in the present and continue into the futureRetrospective: Start in the present, but look to the past for information on medical outcomes and eventsPurpose of Cohort StudiesThe purpose of cohort studies is to help advance medical knowledge and practice, such as by getting a better understanding of the risk factors that increase a person's chances of getting a particular disease.Participants in cohort studies are grouped together based on having a shared characteristic—like being from the same geographic location, having the same occupation, or having a diagnosis of the same medical condition.Each time the researchers check-in with participants in cohort trials, they're able to measure their health behaviors and outcomes over a set period of time. For example, a study could involve two cohorts: one that smokes and the other that doesn't. As the data is collected over time, the researchers would have a better idea of whether there appears to be a link between a behavior—in this case, smoking—and a particular outcome (like lung cancer, for example).Strengths of Cohort StudiesMuch of the medical profession's current knowledge of disease risk factors comes from cohort studies. In addition to showing disease progression, cohort studies also help researchers calculate the incidence rate, cumulative incidence, relative risk, and hazard ratio of health conditions.3Size: Large cohort studies with many participants usually give researchers more confident conclusions than small studies.Timeline: Because they track the progression of diseases over time, cohort studies can also be helpful in establishing a timeline of a health condition and determining whether specific behaviors are potential contributing factors to disease.Multiplemeasures: Often, cohort studies allow researchers to observe and track multiple outcomes from the same exposure. For example, if a cohort study is following a group of people undergoing chemotherapy, researchers can study the incidence of nausea and skin rashes in the patients. In this case, there is one exposure (chemotherapy) and multiple outcomes (nausea and skin rashes).Accuracy: Another strength of cohort studies—specifically, prospective cohort studies—is that researchers might be able to measure the exposure variable, other variables, and the participants' health outcomes with relative accuracy.Consistency: Outcomes measured in a study can be done uniformly.Retrospective cohort studies have their own benefits, namely that they can be conducted relatively quickly, easily, and cheaply than other types of research.How Research Participants Are ProtectedWeaknesses of Cohort StudiesWhile cohort studies are an essential part of medical research, they are not without their limitations.These can include:Time: Researchers aren't simply bringing participants into the lab for one day to answer a few questions. Cohort studies can last for years—even decades—which means that the costs of running the study can really add up.Self-reporting: Even though retrospective cohort studies are less costly, they come with their own significant weakness in that they might rely on participants' self-reporting of past conditions, outcomes, and behaviors. Because of this, it can be more difficult to get accurate results.4Drop-out: Given the lengthy time commitment required to be a part of a cohort study, it's not unusual for participants to drop out of this type of research. Though they have every right to do that, having too many people leave the study could potentially increase the risk of bias.Behavior alteration: Another weakness of cohort studies is that participants may alter their behavior in ways they wouldn't otherwise if they were not part of a study, which could alter the results of the research.Potential for biases: Even the most well-designed cohort studies won't achieve results as robust as those reached via randomized controlled trials. This is because by design—i.e. people put into groups based on certain shared traits—there is an inherent lack of randomization.A Word From VerywellMedicines, devices, and other treatments come to the market after many years of research. There's a long journey between the first tests of early formulations of a drug in a lab, and seeing commercials for it on TV with a list of side effects read impossibly quickly.Think about the last time you had a physical. Your doctor likely measured several of your vital signs and gave you a blood test, then reported back to you about the various behaviors you may need to change in order to reduce your risk of developing certain diseases. Those risk factors aren't just guesses; many of them are the result of cohort studies.
