cohort study

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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.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

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)
Farlex Partner Medical Dictionary © Farlex 2012

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.
Segen's Medical Dictionary. © 2012 Farlex, Inc. All rights reserved.
References in periodicals archive ?
The cohort analysis included 245 intervals with a diagnosis (all of those from the case-crossover analysis plus 17 that were ineligible for that analysis) and 3,896 intervals in which no infection was detected.
(2000) "The policy response to the Employment Task Force and changing patterns of Domestic Purposes Benefit receipt: a cohort analysis" Social Policy Journal of New Zealand, 14:78-103.
Following the trend analyses, The authors report and discuss their findings from age standardization, decomposition, and cohort analysis. The final section summarizes and concludes the study.
Cohort analysis, following the procedures described in Pope (1972), have previously been carried out for yellowfin sole by Bakkala and Wespestad (1986) and Wakabayashi et al.(4) The former analysis has been updated through 1990 for this report (Table 2).
Data Source: A propensity score-matched cohort analysis involving 12,840 elderly patients taking opioids, NSAIDs, or coxibs for rheumatoid arthritis or osteoarthritis pain.
A multi-centre, retrospective cohort analysis was performed in the Netherlands among couples treated with IUI up to nine cycles.
A national cervical cancer screening program put in place by the British government in 1988 reversed the trend of rapidly increasing incidence of the disease that began in the late 1960s, but even that achievement only hints at the program's success) Projections resulting from a birth cohort analysis suggest that without screening, the annual number of diagnoses of invasive cervical cancer would have reached 11,000 in England and Wales by 2030; the annual number of deaths from the disease, 5,500.
NEW ORLEANS -- Neonates born by elective cesarean section are at greater risk of poor outcomes than those born vaginally, and are also at greater risk than those born to women who intended to deliver vaginally but were converted to operative vaginal or cesarean delivery, according to a large retrospective cohort analysis.
However, I would hope that policy analysts would use this book only as an indicator of trends, and go for deeper and more detailed age-group analysis in their sector, particularly cohort analysis. For me, the key issue of the usefulness of this book is the life-cycle approach versus the policy sector approach, and the need for a consideration of total population analysis as well as the breakdown by life-cycle stage, and for more detailed age-group analysis, and particularly cohort analysis.
Alexander Turchin, M.D., from Brigham and Women's Hospital in Boston, and colleagues conducted a retrospective cohort analysis involving adults taking at least one diabetes medication treated in primary care practices.
Under the terms of the partnership, Illumina will make available to Genomics England researchers and the GENE Consortium part of the 100,000 Genomes dataset as a pilot within NextBio Clinical, which will enable cohort analysis of complex phenotypic and genotypic information from de-identified genomes.