Literature critique criteria for casecontrol studies. Casecontrol studies can be useful when a rare event is studied, the sample available is small, or when initial evaluation pilot study of an exposure of interest is necessary. Because the duration, frequency and magnitude of the exposures are not analyzed in many of those studies, most of the conclusions of the committee are made for exposure in general, assuming some recurrent level of recurrent secondhandsmoke exposure. Take all take sample intensive analyses of fewer specimens saves cost increases efficiency temporality assured. Note that it is not possible to estimate the incidence of disease from a case control study unless the study is population based and all cases in a defined population are obtained. Information bias in case control studies occurs when the information obtained from study participants is systematically inaccurate about exposure to the risk factor being studied in casecontrol studies, recall bias is a particular problem. In addition, the temporal sequence of exposure and disease is easier to. In several situations they have greater statistical power than cohort studies, which must often wait for a sufficient number of disease events target disease to accrue.
Consider a casecontrol study intended to establish an association between the use of traditional eye meidicinestem and corneal ulcers. Among the most salient are to observe historical health trends to make useful projections into the future, discover diagnose current health and disease burden in a population, identify specific causes and risk factors of disease, differentiate between natural and intentional events eg, bioterrorism, describe the natural. Cohort studies and casecontrol studies are two primary types of observational studies that aid in evaluating associations between diseases and exposures. Case series, descriptive, and crosssectional studies 6aug14 2 case report and case series detailed description of one or more cases of a disease that are unusual for some reason never seen before occur in unexpected individuals occur in unexpected places example description of. Casecontrol studies matching makes case and control groups more comparable easy to explain and understand timeconsuming, logistically difficult frequency or group matching may be easier cannot study association of matched factor with disease casecontrol studies adjustment accomplished during analysis using. Criteria green yellow red comments selection of controls. This is an excerpt from time, temporality and global politics an eir edited collection available now on amazon uk, usa, ca, ger, fra, in all good book stores, and via a free pdf download. In this paper we present a number of past and present approaches to the definition of temporality. Similarly, in cohort and casecontrol studies the exposures could be chronic or intermittent. Casecontrol studies are often used to identify factors that may contribute to a medical condition by comparing subjects who have that conditiondisease the cases with. A nested casecontrol study design involves the selection of several healthy controls for each case, typically from those still under observation at the time when the case developed the disease 3. The case control case referent design is really an efficient sampling technique for measuring exposuredisease associations in a cohort that is being followed up or study base all casecontrol studies are done within some cohort defined or not in reality, the distinction between cohort and casecontrol designs is artificial. They look back to assess whether there is a statistically significant difference in the rates of. Whenever feasible, conclusions drawn from casecontrol studies should be verified by replication in other designs such as prospective cohort studies.
Case control studies can be useful when a rare event is studied, the sample available is small, or when initial evaluation pilot study of an exposure of interest is necessary. Epidemiology is applied in many areas of public health practice. Nov 03, 20 in this short video, dr greg martin discusses case control and cohort studies. Case series, descriptive, and crosssectional studies. How to assess epidemiological studies postgraduate. What does the word temporal relationship mean here. If reliable data is available on potential exposures prior to the onset of incident cases, there may be some evidence of temporality in a case control study. It costs relatively less and can be conducted in a shorter time for a given disease, a casecontrol study can investigate multiple exposures when the real exposure is not known a casecontrol study is.
Design, conduct, and analysis of case control studies christy mckinney, phd, mph department of oral health sciences university of washington. Introduction to study designs casecontrol studies health. Find out more about eirs range of open access books here. Collect and store bloodurine specimens case control study. In the present chapter we will define and compare various study designs and their usefulness for investigating relationships between an outcome and an exposure or study factor. How to assess epidemiological studies postgraduate medical. Crosssectional studies looks at multiple cohorts over a single point in time. Case control studies have specific advantages compared to other study designs. Case control studies e r i c n o t e b o o k s e r i e s case control studies are used to determine if there is an association between an exposure and a specific health outcome. Cohort studies advantages measure populationbased incidence relative risk and risk ratio estimations rare exposures temporality less likely to be subject to biases recall and selection as compared to casecontrol possible to assess multiple exposures andor outcomes. Table 2 shows these criteria illustrated using the cause effect relationship described for the human papillomavirus and cervical cancer.
In this lesson, we will look at ecological and case control study designs. Casecontrol studies are an efficient method for the study of rare. This means that it can be hard to establish if there is true temporality i. Observational studies can not control for all the things that people do or happen to them, so there is possibility of uncontrolled confounding. Crosssectional studies are a type of descriptive epidemiologic study in which the exposure and disease status of the population are determined at a given point. Nested case control study time yes cases controls prospective cohort study. The temporal relationship between the supposed cause and effect cannot be. Basic principles of epidemiology public health merck.
In a casecontrol study, it is imperative that the investigator has explicitly defined inclusion and exclusion criteria prior to the selection of cases. However, it actually only applies to those case control studies in which controls are sampled only from the nondiseased rather than the whole population. In a cohort study, investigators follow a group of people over time and note each new occurrence of the disease. In theory, the casecontrol study can be described simply. Often these studies are the only practicable method of studying various problems, for example, studies of aetiology, instances where a randomised controlled trial might be unethical, or if the condition to be studied is rare. Instead of looking at the probability of disease given exposure, look at the probability of exposure given disease. Studies may be prospective following the future developing pattern of exposure and illness or retrospective examining past exposures and present illness. Jun 19, 2018 casecontrol studies are an efficient method for the study of rare outcomes, but suffer various limitations, including susceptibility to bias in recollection about exposure. Literature critique criteria for casecontrol studiestabular. Casecontrol studies are an efficient method for the study of rare outcomes, but suffer various limitations, including susceptibility to bias in recollection about exposure. The centers for disease control and prevention cdc asked the institute of medicine iom to convene an expert committee to assess the state of the science on the relationship between secondhandsmoke exposure and acute coronary events. Cohort, cross sectional, and case control studies are collectively referred to as observational studies. A case control study is designed to help determine if an exposure is associated with an outcome i. In this short video, dr greg martin discusses case control and cohort studies.
Begin with the outcome and look for features of people who share that outcome, then compare characteristics with subjects who do not. Jul 28, 2016 this is an excerpt from time, temporality and global politics an eir edited collection. Y temporality known with certainty multiple outcomes in one study yields incidence. To learn when it is ideal to use a case control study design 2. Temporality is particularly difficult to demonstrate in casecontrol studies where all data are collected at once. Casecontrol studies are not interventional studies and are retrospective, so we use odds ratio rather than relative risk as a measure of the association.
First, identify the cases a group known to have the outcome and the controls a group known to be. In these studies, the study sample is selected based on whether the outcome occurred already. Control selection should reflect the exposure distribution of the hypothetical cohort from which the cases arose. Among the causal criteria presented in the text, temporality was mentioned. When case control studies were first developed, most were conducted retrospectively, and it is sometimes assumed that the raredisease assumption applies to all case control studies. Cohort, cross sectional, and casecontrol studies are collectively referred to as observational studies. For example, if the outcome is having a disease, specific diagnostic criteria, disease subtype, stage of disease, or degree of severity should be defined. The odds ratio or represents the odds that an outcome will occur from a particular exposure, compared with the odds of the outcome occurring in the absence of that exposure.
Case control studies trace backwards from outcome to exposure. Review of casecontrol and cohort nested casecontrol crosssectional ecological. Criteria green yellow red comments outcome definition of cases assessed by examiner using history, physical exam, and ancillary diagnostic tests when appropriate symptom patterns reported which are generally recognized as sensitive and specific for the condition symptoms not clearly. Type of study to conduct sampling methods to use measure of association to calculate for a particular study interpret the results of descriptive and analytic studies. In theory, the case control study can be described simply. However, these studies tend to enroll people from broader backgrounds, possibly strengthening the generalizabilty of their results. However, nested casecontrol studies have some limitations. Starting with an outcome like disease, a casecontrol study looks backwards in time for exposures that might have caused the outcome. Casecontrol studies trace backwards from outcome to exposure. Ensures temporality exposure occurs before observed outcome 23.
He compares the strengthes of each study design and descibes when each of them would be a preferred research method. Malonza, md, mph department of reproductive health and research world health organization. In this lesson, we will look at ecological and casecontrol study designs. Cohort studies and case control studies are two primary types of observational studies that aid in evaluating associations between diseases and exposures. This means results lack the element of temporality and therefore causality cannot be implied from these studies. Casecontrol studies selection of a comparison group, i.
A study is defined as a type of casecontrol study in which cases and controls are drawn from the population in a cohort study. While cohort studies are sampled according to exposure, characteristic or cause, casecontrol studies are sampled according to disease or outcome. A casecontrol study also known as casereferent study is a type of observational study in which two existing groups differing in outcome are identified and compared on the basis of some supposed causal attribute. Study designs included are i cohort studies general prospective cohort.
Crosssectional studies collect all data at a set point in time. Gehlbach, interpreting the medical literature, 1993 casecontrol studies start with a disease, and work backward to find associations between exposures and the disease. In cancer development, it isverydifficulttodistinguishdriversandpassengers,and this prohibits the identification. To learn how selection bias can occur and some strategies to minimize it. Of the following study designs, which is best for establishing temporality.
Thelle, petter laake, in research in medical and biological sciences second edition, 2015. Pdf casecontrol study design is a type of observational study. First, identify the cases a group known to have the outcome and the controls a group known to be free of the outcome. The authors 2016 in studying the human microbiome and. It remains to this day a model for the design and conduct of casecontrol studies, with excellent suggestions on how to. A casecontrol study is designed to help determine if an exposure is. The landmark study of doll and hill 1950, 1952, in particular, inspired future generations of epidemiologists to use this methodology. Descriptive and analytic studies presenters name presenters title.
Starting with an outcome like disease, a case control study looks backwards in time for exposures that might have caused the outcome. Design, conduct, and analysis of case control studies. Casecontrol studies e r i c n o t e b o o k s e r i e s casecontrol studies are used to determine if there is an association between an exposure and a specific health outcome. Analysis of casecontrol studies the odds ratio or is used in case control studies to estimate the strength of the association between exposure and outcome. Cross sectional study an overview sciencedirect topics. A casecontrol study is designed to help determine if an exposure is associated with an outcome i. Compare diseased with not diseased on previous exposures. Define and give the formula for a relative risk rr. In cancer development, it isverydifficulttodistinguishdriversandpassengers,and this prohibits the identification of early markers of the disease.
Descriptive and analytic studies learning objectives identify the following for an ncd problem. Efficient use of biological specimens and resources, e. The most common measurement of association in casecontrol studies is the odds ratio. Traditionally, casecontrol studies have been viewed as an alternative to cohort studies in which individuals were selected on the basis of whether or not they had the disease outcome of interest, with investigators then comparing exposure history between those with the disease the cases and those free of the disease the controls.
Available now on amazon uk, usa, ca, ger, fra, in all good book stores, and via a free pdf download. Pdf a reflection on the role of temporality in translation history. A cohort study is one of the observational study designs which is used to evaluate association between exposure and disease. Or stands for odds ratio and rr stands for relative risk. Groups of individuals that share something in common and studying them at a certain point in time. Nested casecontrol versus casecohort study nested casecontrol. Longitudinal studies looks at cohorts forward and back in time. Temporary 3, presenttimewise casecontrol studies may prove an association but they do not demonstrate causation.
This work is licensed under a creative commons attribution. A casecontrol study is usually conducted before a cohort or an experimental study to identify the possible etiology of the disease. They look back to assess whether there is a statistically significant difference in the rates of exposure to a defined risk factor between the groups. Case series, descriptive, and crosssectional studies 6aug14 2 case report and case series detailed description of one or more cases of a disease that are unusual for some reason never seen before occur in unexpected individuals occur in unexpected places example description of series of infants born with. A brief introduction to temporality and causality kamran karimi dwave systems inc.
Casecontrol studies can be useful but have many limitations. While cohort studies are sampled according to exposure, characteristic or cause, case control studies are sampled according to disease or outcome. Crosssectional are weaker since they cannot establish temporal precedence. Compared to prospective cohort studies, casecontrol study tends to be less costly and shorter in duration. In a casecontrol study, persons with the disease of interest the cases and persons without.
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