As a researcher, one can face the dilemma of choosing between many different types of research or studies designs, to determine which one will be the more suitable for the kind of topic we are investigating. Recently, a number of studies have been published using the term casecontrol study in the title to describe the study design. A case control study was conducted to investigate if exposure to zinc oxide is a more effective skin cancer prevention measure. I will describe the basic design of case control studies and discuss their strengths and weaknesses. Case control studies have been widely used in genetic studies to identify susceptibility genes and are the best design to study rare conditions, as they are efficient in use of time and money, collecting a lot of relevant information on targeted individuals. The study involved comparing a group of former lifeguards that had developed cancer on their cheeks and noses cases to a group of lifeguards without this type of cancer controls and assess their prior exposure to. On closer examination these studies turn out to be nothing of the kindat least, not in the sense in which the term is understood by epidemiologists. With case control study design, the associated risk factors and diseases may be promptly identified, and establishment of causation is more powerful than in a crosssectional study 107. 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. In these situations a case control design offers an alternative that is much more efficient.
Cases should be selected based on objective inclusion and exclusion criteria from a reliable source such as a disease registry. Tests for two correlated proportions in a matched case. Both exposure and outcome have occurred before the start of the study. The control population can only be used for one specific outcome the disease that the cases have, because of the timematching incidence sampling. Casecontrol studies a case control study involves two populations cases and controls and has three distinct features. The goal of a case control study is the same as that of cohort studies, i. Study design is the procedure under which a study is carried out study design is the procedure under which a study is. The casecontrol design is sensitive to both differential reporting and selection bias, and the choice of study design involves balancing these two sources of bias.
The case control design is sensitive to both differential reporting and selection bias, and the choice of study design involves balancing these two sources of bias. This module introduces the following study designs. Casecontrol research subjects chosen based on disease status and assessed for previous illness to a risk factor of interest. She dives into detail on crosssectional and casecontrol studies, and shows how to plan an analytic data set. However, case control studies employ a different sampling strategy that gives them greater efficiency. Case control study design is a type of observational study. Select the twosided confidence level of 95% from the dropdown list. The case control design is an observational design in which study groups are defined by the response variable rather than by the explanatory variable. The cases and controls are then compared with respect to the frequency of one or more past exposures. Kingshuk roy choudhury and daniel barboriak, department of. I will describe the basic design of casecontrol studies and discuss their strengths and weaknesses. A case control study is a kind of research design in which two subsisting groups varying in outcome are differentiated and classified on the basis of some conjectured casual characteristic.
Using sas to match cases for a casecontrol study wenbin li may 10, 2012. Case control study, in epidemiology, observational nonexperimental study design used to ascertain information on differences in suspected exposures and outcomes between individuals with a disease of interest cases and comparable individuals who do not have the disease controls. Scanningcenter richflorida accessrestricteditem true addeddate 20140718 20. There are two basic types of casecontrol studies, distinguished by the method used to select controls. The casecontrol design uses a different sampling strategy in which the investigators identify a group of individuals who had developed the disease the cases and a comparison of individuals who did not have the disease of interest. 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. As noted in earlier focus issues on study design, analytic studies are conducted to answer the question, what is the relationship between exposure and disease. The response variable is usually binary that is an individual either has a particular condition a case or does not have that condition a control. With casecontrol study design, the associated risk factors and diseases may be promptly identified, and establishment of causation is more powerful than in a crosssectional study 107. In this design, participants are selected for the study based on their outcome status. Casecontrol studies compare cases and diseasefree controls for their exposure status and compare the risk of exposure in cases and controls. Case study design definition of case study design by. However, where a certain outcome is rare then a prospective cohort study is inef. Case studies are appropriate when there is a unique or interesting story to be told.
Asan efficient alternative to the case initiated study some authors employed a control initiated design,3334 whereby the investigator uses the same control series morethan once, to study different diseases anddifferent exposures. In this study design, the number of controls does not necessarily equal the number of cases. The effect of potential problems in obtaining comparable accuracy. There are two basic types of case control studies, distinguished by the method used to select controls. However, case studies typically describe a program or intervention put in place to address a particular problem. Casecontrol study, in epidemiology, observational nonexperimental study design used to ascertain information on differences in suspected exposures and outcomes between individuals with a disease of interest cases and comparable individuals who do not have the disease controls. 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. This work is licensed under a creative commons attribution. Thus, case control studies also allow more intensive. The first is a nonmatched casecontrol study in which we enroll controls without regard to the number or characteristics of the cases.
This section introduces you to basic concepts, application and strengths of case control study. The nested case control study design or the case control in a cohort study is described here and compared with other designs, including the classic case control and cohort studies and the case cohort study. Additionally, investigators can avoid the logistical challenges of following a large sample over time. This design has been used infrequently, and it does not offer any advantage over the case initiated design in. Introduction to study designs casecontrol studies health. Aug 15, 2003 the case crossover design, unlike the case control and the case time control designs, avoids differential recall between mothers of cases and mothers of controls, but within person recall of exposures may be different across study periods. Casecontrol study design is a type of observational study. Not entirely true, if known sampling fractions in each riskset then controls can be reused.
A casecontrol study is a kind of research design in which two subsisting groups varying in outcome are differentiated and classified on the basis of some conjectured casual characteristic. This is partly due to that the nested case control design has been around longer, since thomas 1976 compared to prentice 1986. This study design was first recognized in janet laneclaypons study of breast cancer in 1926, revealing the finding that low fertility rate raises the risk of breast cancer. The casecontrol design is an observational design in which study groups are defined by the response variable rather than by the explanatory variable. The case control design uses a different sampling strategy in which the investigators identify a group of individuals who had developed the disease the cases and a comparison of individuals who did not have the disease of interest. An inherent issue with selecting cases is that a certain proportion of those with the disease would not have a formal diagnosis, may not present for medical care, may be misdiagnosed or may. Enter the desired power 80% to detect a group difference at that confidence level. The first is a nonmatched case control study in which we enroll controls without regard to the number or characteristics of the cases. Study design 4 present key elements of study design early in the paper setting 5 describe the setting, locations, and relevant dates, including periods of recruitment, exposure, followup, and data collection a give the eligibility criteria, and the sources and methods of case ascertainment and control selection. In the nested casecontrol study, cases of a disease that occur in a defined cohort are identified and, for each, a specified number of. Case control research subjects chosen based on disease status and assessed for previous illness to a risk factor of interest. Usually, cases are people with disease, but treatment outcomes or other criteria can be used to define a case.
This is partly due to that the nested casecontrol design has been around longer, since thomas 1976 compared to prentice 1986. The study uses a casecontrol design that examines the differences in types of exposures between symptomatic individuals with laboratory confirmed ncov infection and healthy controls in order to determine the risk associated with that exposure. It uses a control or comparison group to support or refute an inference. Case cohort study designs were proposed as an alternative to the nested case control study design. A casecontrol study was conducted to investigate if exposure to zinc oxide is a more effective skin cancer prevention measure. Video created by the university of north carolina at chapel hill for the course epidemiology. Cohorts permit calculation of the effect of each variable on the probability of developing the outcome of interest relative risk. Using sas to match cases for a case control study wenbin li may 10, 2012.
Analysis of case control studies the odds ratio or is used in case control studies to estimate the strength of the association between exposure and outcome. Case studies do not have set elements that need to be included. Thus, casecontrol studies also allow more intensive. Case control studies may be nested within cohort studies. As discussed in the previous chapter, one of the drawbacks of using a longitudinal approach to investigate the causes of disease with low incidence is that large and lengthy studies may be required to give adequate statistical power. Case control studies are one of the frequently used study designs due to the relative ease of its application in comparison with other study designs. Jan 29, 20 case control studies are observational studies that have the greatest risk of bias. Advantages of casecontrol studies casecontrol studies are the most efficient design for rare diseases and require a much smaller study sample than cohort studies.
The case group is composed only of individuals known to have the disease or outcome. Thus, some participants have the outcome of interest referred to as cases, whereas others do not have the outcome of interest referred to as controls. Analysis of casecontrol studies the odds ratio or is used in casecontrol studies to estimate the strength of the association between exposure and outcome. Note that it is not possible to estimate the incidence of disease from a casecontrol study unless the study is population based and all cases in a defined population are obtained. Casecontrol study a study that identifies individuals who develop the disease cases and individuals without the disease controls, and then determines the previous exposure for each case and control. Casecontrol designs nested casecontrol design ncc is an option with appropriate sampling and analysis, the or estimates the hr in the full cohort casecohort design is another option. Casecontrol study an overview sciencedirect topics. Dec 29, 2016 casecontrol studies a case control study involves two populations cases and controls and has three distinct features. Topics covered include matching, controlcase ratio, choice of nested casecontrol or casecohort design, twostage sampling, and other methods that can be used for control selection. Casecontrol study to assess potential risk factors related. Casecohort study designs were proposed as an alternative to the nested casecontrol study design. Casecontrol studies advantages good design for rare, chronic and long latency diseases relatively inexpensive population size and time allows for the examination of multiple exposures estimate odds ratios hospitalbased studies and outbreaks.
Several design options available in the planning stage of casecontrol studies are examined. Casecontrol studies are observational studies that have the greatest risk of bias. Case control studies compare cases and diseasefree controls for their exposure status and compare the risk of exposure in cases and controls. The nested casecontrol study design or the casecontrol in a cohort study is described here and compared with other designs, including the classic casecontrol and cohort studies and the casecohort study. This is a single value and the proportion cannot be entered in the format. Advantages of case control studies case control studies are the most efficient design for rare diseases and require a much smaller study sample than cohort studies. In the nested case control study, cases of a disease that occur in a defined cohort are identified and, for each, a specified number of. An alternative which avoids this difficulty is the case control or case referent design. Some of these patients have had exposure to a risk factor of interest. She dives into detail on crosssectional and case control studies, and shows how to plan an analytic data set. The casecontrol study design is often used in the study of rare diseases or as a preliminary study where little is known about the association between the risk factor and disease of interest. Casecrossover and casetimecontrol designs in birth defects. Case control study a study that identifies individuals who develop the disease cases and individuals without the disease controls, and then determines the previous exposure for each case and control.
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