Types of study designs in epidemiology pdf

A major goal of epi research is to explain patterns of disease occurrence and causation etiology epi measurements are aimed at quantifying 3 things. Descriptive study designs health research fundamentals. Finally, association versus causal relationships will. Types of epidemiology descriptive epidemiology study of distribution of health states incidence, prevalence time place person analytic epidemiology study of the risk factors for health states. The second course, study designs in epidemiology, provides an overview of the most common study designs, their strengths and limitations.

The next two designs are regarded as primarily descriptive, the last design is primarily analytic, and designs 5 and 6 can be employed in analytic hypothesis testing or descriptive modes, depending upon the extent to which the study is oriented towards a preexisting specific hypothesis. Measures of risk for the exposureoutcome relationship that can be calculated in crosssectional study design are odds ratio, prevalence odds ratio, prevalence ratio, and prevalence difference. Types of epidemiological studies you should know new. A retrospective study is one where the study starts after the exposure and probably outcome has been ascertained. Conclusions from nonrandomized studies subject to many sources of bias the randomized clinical trial is the epitome of all research designs because it provides the strongest conclusions from nonrandomized studies subject to 33. Analytic study designs in this presentation i will cover experimental studies, which are different than observational studies in that the researcher allocates treatment or exposure to study participants. Thus, experimental studies in epidemiology are limited to interventions that are believed to be of potential benefit.

Next month, will discuss how to choose a statistical. Depending on the type of research question, practicability, and resources in terms of manpower, money and time, the investigator has to choose the appropriate study design which will answer the. Case series are studies that describe in detail a group of subjects who share common characteristics andor have received similar interventions. The most commonly used analytical study designs are listed here and are covered in this module. Introduction to ncd epidemiology ncd burden of disease ncd data sources surveillance in public health. Included quiz questions south african heart patients were asked about their experiences with alcohol, then this was compared with the alcohol experiences of gastric bypass patients in the same hospital wing. May 05, 2017 this video gives a simple overview of the most common types of epidemiological studies, their advantages and disadvantages. These include ecological, caseseries, case control, cohort and. To appreciate use of epidemiologic study designs for a variety of applications of potential practical importance z. Im on the clinical faculty at the northwest center for public health practice, at the school of public health and community medicine, university of washington in seattle.

Research design is a framework of methods and techniques chosen by a researcher to combine various components of research in a reasonably logical manner so that the research problem is efficiently handled. Types of questions domains etiology cohort, case control therapy rct prognosis cohort harm cohort, case control diagnosis crosssectional, casecontrol economic costeffectiveness analysis, etc. Epidemiologic study types have their roots in the concepts of scientific experimenta tion. Observational studies are inherently more vulnerable to the effect of bias and confounding. Introduction to study designs intervention studies and. Difference between descriptive and analytic epidemiology. Introductory epidemiology hsc4933 analytic studies analytic epidemiology types of study design factors to help identify the type. Learn vocabulary, terms, and more with flashcards, games, and other study tools. The cohort study is often referred to as the gold standard of observational study designs and is a form of. Descriptive studies include case reports, caseseries.

Essentially, the investigator selects a group of persons with a disease of interest cases, and then selects a group of persons who do not have the. Epidemiology of study design statpearls ncbi bookshelf. Basic epidemiology starts with a definition of epidemiology, introduces the history of modern epidemiology, and provides examples of the uses and applications of epidemiology. In this article, you will learn about the types of epidemiological studies and gain information regarding the issues which are to be kept in mind when understanding the results of the various study designs. Introduction to epidemiology outline what is epidemiology. Fundamentals of epidemiology experimental studies transcript page 2 covered in another prese slide 4. This type of research design draws a conclusion by comparing subjects against a control group, in cases where the researcher has no control over the experiment. Analytic epidemiology refers to the studies which are conducted to test for hypotheses and to generate conclusions on the particular disease. Epidemiologic study designs epidemiology learning materials. These domains are usually addressed by different study designs.

Crosssectional study objective to estimate the magnitude and patterns of violence against pregnant women study populationbased, household, crosssectional study in mbeya and dar es salaam, tanzania, 20012002 result violence experienced by 7% in dar es salaam and 12% in mbeya. To appreciate use of epidemiologic study designs for a variety of. The cohort study is often referred to as the gold standard of observational study designs and is a form of longitudinal study that is commonly. A nonanalytic or descriptive study does not try to quantify the relationship but tries to give us a picture of what is happening in a population, e. The strength of the rct lies in the process of randomisation that is unique to this type of epidemiological study design. Pdf overview of study design in clinical epidemiology. A metaanalysis is a statistical process that combines the findings from individual studies. Principles of study design in environmental epidemiology. The purpose of the study design is to transform the conceptual hypothesis into an operational hypothesis that can be empirically tested all study designs are potentially flawed important to understand the specific strengths and limitations of different study designs. Introduction to epidemiological study designs introduction. Understand key considerations in designing a study, including randomization, matching and blinding.

Design issues edgar r miller iii phd, md welch center for prevention, epidemiology and clinical research johns hopkins university school of medicine and bloomberg school of public health 2 type of studies nonexperimental observational case report case series crosssectional survey. Identify types of research design commonly used in. In an experimental study design, researchers assign patients to. The most common study designs used in epidemiology casecontrol, crosssectional, and cohort studies will also be discussed. In the following article, you can read everything on study designs, types of studies, data acquisition and interpretation. Overview of study designs university of california, davis. Observational and interventional study design types. Study design practice exam questions seethesolutions. Epidemiology is the study of the determinants, distribution, and frequency of disease who gets the disease and why i i epidemiologists study sick people i epidemiologists study healthy people i to determine the crucial di. The cases do not develop until after the study begins and the cases are enrolled in the study over time.

Observational studies casecontrol study casecontrol studies are common study designs used in oral health research. Filippos filippidis, and in this course, with the help of my experienced colleagues at imperial college london, we will introduce you to the main study designs in epidemiological research. Classification of epidemiological study designs article in international journal of epidemiology 412. Clinical study design is the formulation of trials and experiments, as well as observational studies in medical, clinical and other types of research e. Understand the strengths and limitations of each type of study design, as applied to a particular research purpose. The goal of a clinical study is to assess the safety, efficacy, and or the mechanism of action of an investigational medicinal product imp or procedure, or new drug or device that is in. Concerned with the frequencies and types of illnesses and injuries in groups of people and the. There are several types of epidemiological studies figure 1. In epidemiology, researchers are interested in measuring or assessing. Study designs in medical research university of chicago.

Classification of epidemiological study designs request pdf. Our first distinction is whether the study is analytic or nonanalytic. Introduction to epidemiology and study designs janusz kaczorowski phd university of british columbia. Experimental, quasiexperimental, and descriptive chapter outline introduction experimental study designs quasiexperimental designs descriptive quantitative designs additional types of designs researcher interview.

The randomised controlled trial is considered as the most rigorous method of determining whether a causeeffect relationship exists between an intervention and outcome 2. Describe the basic types of epidemiologic study designs that. In direct observations, people know that you are watching them. Epidemiologic study designs johns hopkins medicine. The third course, validity and bias in epidemiology, builds on the fundamental concepts taught in the previous courses to discuss bias and confounding and how they might affect study results.

Anxiety outcomes after physical activity interventions. A mortality odds ratio mor is reported when mortality is studied. This video gives a simple overview of the most common types of epidemiological studies, their advantages and disadvantages. Last in 1988 as, the study of the distribution and determinants of health related states or events in specified populations, and the application of this study to the control of health problems. Seminar objectives provide an overview of different types of study designs. Identify types of research design commonly used in epidemiological studies. There are two primary types of nonexperimental studies in epidemiology.

Education corner classification of epidemiological study designs. Incidence studies ideally measure exposures, confounders and outcome times of all population members. A way of combining data from many different research studies. Measurement of exposure and disease are covered in chapter 2 and a summary of the different types of study designs and their strengths and limitations is provided in. Procedures in the studys design and conduct are used to prevent or reduce possible bias. The first, the cohort study also called thefollowup study or incidence study, is a direct analogue of the experiment. Centre for animal disease research and diagnosis indian veterinary research institute, izatnagar243122, bareilly, up, india. Crosssectional, cohort, and casecontrol study retrospective.

I will argue that when the individual is the unit of analysis and the disease outcome under study is dichotomous, then epidemiological study designs can best be classified according to two criteria. Study types in epidemiology 1 study types in epidemiology welcome to study types in epidemiology. Other study types, such as case series, casecontrol studies, cohort studies, crosssectional studies, crossover designs, and openlabel studies, may be required to hypothesize and evaluate the link between an exposure or predictor variable and an outcome variable. Point prevalence and period prevalence can be calculated in crosssectional studies. Kirsten bibbinsdomingo, phd, md assistant professor of medicine and of epidemiology and biostatistics university of california, san francisco. Ethical considerations naturally prevent us from allocating potentially harmful exposures on an experimental basis in human populations. The purpose of this article is to provide a brief overview of the range of study designs used to address research questions in clinical epidemiology. At, we provide access to the bestquality, bestvalue private tutoring service possible, tailored to your course of study. Following background sections on the quantitative objectives and methods of populationbased research, we present the major types of observational designs used in environmental epidemiology. However, these problems can be minimized by good study design.

Epidemiology studies are conducted using human populations to evaluate whether there is a correlation or causal relationship between exposure to a substance and adverse health effects these studies differ from clinical investigations in that individuals have already been administered the drug during medical treatment or have been exposed to it in the workplace or environment. Epidemiologists must have a sound understanding of the principles of study design. A crosssectional study is an example of a descriptive epidemiologic study that we will discuss on the next slide. Provide an overview of different types of study designs. Download a pdf by jeremy howick about study designs. Introduction to epidemiological study designs oxford medicine. Study designs in epidemiology for formation and evaluation of causal hypothesis and for comparison of groups of animals dr.

Read all about research design definition, characteristics, and types. Epidemiologic study designs descriptive studies seeks to measure the frequency of disease andor collect descriptive data on risk factors analytic studies tests a causal hypothesis about the etiology of disease experimental studies compares, for example, treatments. Welcome to the second course in the epidemiology for public health specialization. Types of bias selection bias unrepresentative nature of sample information misclassification bias errors in measurement of exposure of disease confounding bias distortion of exposure. Population from which the cases and controls are obtained.

These fall under experimental and observational designs. North carolina center for public health preparedness training website. The extension to continuous exposure measures requires minor changes to the data analysis, but it does not alter the 4fold categorization of study design options presented above. The types of measures in ecological studies are aggregates of individuallevel data. Two basic measures of an association between exposure and disease in analytical studies are the rate ratio or relative risk rr and exposure odds ratio or. After this, you will be prepared for your next exam and you will know exactly which types of questions you should ask your patient at which point during the anamnesis. Exploratory studies used when the state of knowledge about the. The key difference between descriptive and analytic epidemiology is the approach taken to address the particular health issue.

Summary by raywat deonandan, phd is from the course types of studies. Describe the basic types of epidemiologic study designs that are used to test hypotheses, identify associations and establish causation. For readers with a particular research question in mind, comparison of the different options may guide selection of an appropriate study design. Epidemiology is the study of the distribution, determinants and control of diseases in populations in order to make inferences about individuals needs to sample many clinical epidemiology is the study of determinants of disease outcome in individuals with disease. Objectives to understand the difference between descriptive and analytic studies to identify the hierarchy of study designs, and the strengths and weakness of each design. Other terminology important for epidemiological studies design module. Analytic study designs the architecture of the various strategies for testing hypotheses through epidemiologic studies, a comparison of their relative strengths and weaknesses, and an in depth investigation of major designs. A common application is in epidemiology for estimating an individuals risk probability of a disease as a. Bhoj r singh, principal scientist vm ic epidemiology. There are two general types of observational designs. It is a type of observational study in which two existing groups differing in outcome are.