retrospective study

retrospective study,

a study in which a search is made for a relationship between one (usually current) phenomenon or condition and another that occurred in the past. An example is a study of the family histories of young women diagnosed as having clear cell adenomas of the vagina, which yielded a relationship between the administration of diethylstilbestrol to the mothers of the women during pregnancy and the development of the condition in the daughters. See also case-control 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.

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retrospective study,

a study in which a search is made for a relationship between one phenomenon or condition and another that occurred in the past (e.g., the exposure to toxic agents and the rate of occurrence of disease in the exposed group compared with a control group not exposed).

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study

a scholarly examination. Specific types of study are also detailed under blind, case-control, cohort, cross-sectional.

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analytical study

one in which a phenomenon is described and an attempt made to analyze the effects of variables on the phenomenon.

descriptive study

one in which a phenomenon is described but no attempt is made to analyze the effects of variables on the phenomenon.

follow-up study

one carried out to find out whether there has been change in the situation since the initial study.

longitudinal study

one carried out over a period of time so that chronological time has an opportunity to exert an effect as a variable.

observational study

see descriptive study (above).

prospective study

one in which the data to be studied are yet to be generated, the events having not yet occurred.

retrospective study

one based on examination of existing data, on events that have already occurred.

simulation study

one in which the real circumstances are simulated, either in fact, or by means of a set of mathematical formulae each of which expresses the probability of each outcome in a series of consequential events that mirror the possible pathways in a real-life situation.

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retrospective study

Case-control study Epidemiology An epidemiologic study that analyzes data collected before a certain point in time, to determine if past events are related to the present distribution of disease; a study–eg, case control study in which investigators select groups of Pts who have already been treated and analyze data from the events experienced by these Pts. Cf Prospective study.