cohort study


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study

 [stud´e]
a careful examination of a phenomenon; see also design.
cohort study prospective study.
cross-sectional study one employing a single point of data collection for each participant or system being studied. It is used for examining phenomena expected to remain static through the period of interest. It contrasts with a longitudinal s.
electrophysiological s's (EPS) studies from within the heart of its electrical activation and response to electrical stimuli and certain drugs. In general they include intravenous and/or intra-arterial placement of one or more electrode catheters at sites in the atria, ventricles, or coronary sinus, and sometimes the pulmonary artery or aorta. They record activity or stimulate the heart at various rates and cadences and are aids in the evaluation of electrophysiologic properties such as automaticity, conduction, and refractoriness. They also initiate and terminate tachycardias, map the sequence of activation, and aid in evaluation of patients for various forms of therapy and for the response to therapy. During these studies catheter ablation procedures, such as radio frequency ablation and electrical ablation, may be performed.
flow study uroflowmetry.
longitudinal study one in which participants, processes, or systems are studied over time, with data being collected at multiple intervals. The two main types are prospective studies and retrospective studies. It contrasts with a cross-sectional s.
pilot study a smaller version of a proposed research study, conducted to refine the methodology of the later one. It should be as similar to the proposed study as possible, using similar subjects, the same setting, and the same techniques of data collection and analysis.
prospective study an epidemiologic study in which the groups of individuals (cohorts) are selected on the bases of factors that are to be examined for possible effects on some outcome. For example, the effect of exposure to a specific risk factor on the eventual development of a particular disease can be studied. The cohorts are then followed over a period of time to determine the incidence rates of the outcomes being studied as they relate to the original factors in question. Called also cohort study.



The term prospective usually implies a cohort selected in the present and followed into the future, but this method can also be applied to existing longitudinal historical data, such as insurance or medical records. A cohort is identified and classified as to exposure to the risk factor at some date in the past and followed up to the present to determine incidence rates. This is called a historical prospective study, prospective study of past data, or retrospective cohort study.
retrospective study an epidemiologic study in which participating individuals are classified as either having some outcome (cases) or lacking it (controls); the outcome may be a specific disease, and the persons' histories are examined for specific factors that might be associated with that outcome. Cases and controls are often matched with respect to certain demographic or other variables but need not be. As compared to prospective studies, retrospective studies suffer from drawbacks: certain important statistics cannot be measured, and large biases may be introduced both in the selection of controls and in the recall of past exposure to risk factors. The advantage of the retrospective study is its small scale, usually short time for completion, and its applicability to rare diseases, which would require study of very large cohorts in prospective studies. See also prospective s.
urinary flow study uroflowmetry.
voiding pressure study simultaneous measurement of bladder contraction, urinary flow, and sphincter electromyogram.

co·hort stud·y

a study using epidemiologic methods, such as a clinical trial, in which a cohort with a particular attribute (for example, smokers, recipients of a drug) is followed prospectively and compared for some outcome (for example, disease, cure) with another cohort that does not possess that attribute.
Synonym(s): follow-up study (1)

cohort study

An observational study in which a defined group of people (a cohort) is followed over time and outcomes are compared in subsets of the cohort who were exposed, not exposed, or exposed at different levels to an intervention or other factor of interest. Cohorts can be assembled in the present and followed into the future (a “concurrent cohort study”), or identified from past records and followed from that time up to the present (a “historical cohort study”). Because random allocation is not used, matching or statistical adjustment must be used to ensure that the comparison groups are as similar as possible.
References in periodicals archive ?
Although the participants were experienced with research efforts in the community, the focus group also revealed that there is not a common understanding of what a cohort study is (i.e., long-term observational study).
Consumption of filtered and boiled coffee and the risk of incident cancer: a prospective cohort study. Cancer Causes Control.
The existing cohort studies are well placed to continue following the lives of their members and a new cohort study is joining the portfolio on a larger scale than anything done so far.
The Department of Defense sponsors the Millennium Cohort Study. The primary aim is to follow military personnel over time to assess their health risks during active duty and thereafter.
Overall, perioperative meningitis occurred in 2.1 cases per 1,000 surgeries in the cohort study.
No cohort study has shown evidence of an ABC link, at least for abortions performed in the first trimester.
For example, while one recent prospective cohort study reported an increased risk for meningococcal disease (relative risk 23.8, confidence interval 7.4-76.7; p [is less than] 0.001) in HIV-infected patients in the Atlanta metropolitan area (12), a case-control study in Africa showed no link between HIV infection and epidemic meningococcal disease (14).
Black children and adolescents with renal failure are less likely to be placed on the waiting list for kidney transplantation than their white counterparts, according to a national longitudinal cohort study conducted by researchers at Johns Hopkins Medical Institution in Baltimore, MD.
Lyketsos of the Johns Honkins University School of Medicine in Baltimore and his colleagues found similar rates of CD4 cell decline among depressed and nondepressed participants in the Multicenter AIDS Cohort Study, they report.
the subject of the contract is the provision of the following services: 1) provision of personal data on health status and questionnaire data of middle age cohort study participants (4,000 participants) 2) ensuring the collection of venous blood samples for part of the middle-aged cohort study participants (400 participants) 3) providing anonymized data on the health status of participants in the case study of middle age (70,000 participants) 4) providing questionnaire data of participants in the cohort study of mothers and children (600 mothers) 5) activities related to the collection, Management and transmission of acquired data (preparation of an electronic form of the questionnaire, Preparation of a web interface, Preparation of a data interface and data transmission).
ISLAMABAD -- The Ministry of National Health Services (NHS) has decided to undertake a birth cohort study in Pakistan.