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What is follow up in cohort studies?
In cohort studies a group of individuals are sampled from a source population and followed over time to ascertain the occurrence of an outcome of interest 1. Such cohort data are often analyzed using a time-to-event framework given the frequent occurrence of loss to follow up.
Is there follow up in retrospective cohort study?
(In retrospective cohort studies the follow-up period begins in the past.) The groups being compared differ in their exposure status. One measures and compares the incidence of the outcome in order to determine whether there is an association between the exposure and the outcome.
Can you suggest ways cohort studies can limit loss to follow up?
Since there is no way of predictiing the effects of loss to follow up, researchers do their best to reduce it by maintaining contact with participants at regular intervals, collecting contact information from friends or relatives that would know how to reach a participant should s/he move, using the National Death …
Do case controls have follow up?
In a case-control study there is no “follow-up” period. In a case-control study, you cannot measure incidence, because you start with diseased people and non-diseased people, so you cannot calculate relative risk. The case-control design is very efficient.
What is a good follow-up rate?
A good rule of thumb is that <5% loss leads to little bias, while >20% poses serious threats to validity. However, even less than 20% loss to follow-up can be a problem. Considering a worst-case scenario can help determine whether loss to follow-up poses a potential threat to validity.
What is acceptable loss to follow-up?
Is death lost to follow up?
In clinical medicine and research, loss to follow up refers to a person who has not returned for continued care or evaluation (e.g., because of death, disability, relocation, or drop-out).