Question

a.one of the major problems with cohort studies is loss to follow-up. b.confounders are not a problem with cohort studies since these studies are essentially prospective in design. c.cohort studies are useful for examining multiple outcomes of a single rare exposure. d.cohort studies are generally quicker and less expensive than case-control studies.  

Answer 1

Loss of follow-up is a problem in most cohort studies and often introduces bias. It is a situation in which a researcher loses contact with a subject, resulting in missing data. Too many subjects failing follow-up diminish the internal validity of the study.

What is follow-up loss in cohort studies?

• Follow-up loss introduces bias (observed deviation of relevant measures from what would have been observed without bias) if there is a difference in the likelihood of loss due to follow-up  related to exposure status and outcome.
• In the clinical research trials industry, loss due to follow-up is defined as patients who were actively participating in a clinical research trial at some point but who lost themselves (due to errors in the computer tracking system or due to unavailability).
• In cohort studies: 1) Imaging outcome, is loss of follow-up. 2) These are essentially prospective studies, so confounding factors are not an issue. 3) These studies help examine multiple outcomes from a single, infrequent exposure. 4) These are usually faster and cheaper than case-control studies.

What are advantage and disadvantages of cohort studies?

• In general, the main advantage of cohort studies is the ability to study multiple exposures and multiple endpoints in a single cohort. This recording allows you to select index groups, so you can explore rare recordings.
• A major weakness of cohort studies is that this type of study design can be time consuming and expensive for results that are rare or evolve over long periods of time. It's a question of research.

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