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When is effect modification present in measure?
What is effect modification?
Does the effect modifier have a causal effect?
Is effect modification a confounder?
Learning Objectives. After reading this chapter, you will be able to do the following: Explain what effect modification is. Differentiate between confounders and effect modifiers. Conduct a stratified analysis to determine whether effect modification is present in the data. In the prior chapter, we discussed confounding.
Effect modifier is a variable that differentially (positively and negatively) modifies the observed effect of a risk factor on disease status. Consider the following examples: The immunization status of an individual modifies the effect of exposure to a pathogen and specific types of infectious diseases.
- Effect Modification
- Confounding
- What Is The difference?
Effect modification is all aboutstratification and occurs when an exposure has a different effect among different subgroups. Effect modification is associated with the outcome but not the exposure. For example, imagine you are testing out a new treatment that has come onto the market, Drug X. If Drug X works in females but does not work in males, t...
Confounding occurs whena factor is associated with both the exposure and the outcome but does not lie on the causative pathway. For example, if you decide to look for an association between coffee and lung cancer, this association may be distorted by smoking if smokers are unevenly distributed between the two groups. It may appear that there is an ...
Confounding factors are a “nuisance” and can account for all or partof an apparent association between an exposure and a disease. Confounding factors simply need to be eliminated to prevent distortion of results. Effect Modificationis not a “nuisance”, it in fact provides important information. The magnitude of the effect of an exposure on an outco...
Effect modification occurs when the effect of a factor is different for different groups. We see evidence of this when the crude estimate of the association (odds ratio, rate ratio, risk ratio) is very close to a weighted average of group-specific estimates of the association.
Aug 1, 2012 · With definition 4, effect modification is said to be present in measure μ if the effect of the exposure using measure μ (e.g. the risk difference, risk ratio, or odds ratio scale) varies across strata of Q. Definition 4 is the definition that is generally considered when effect modification is in view.
- T J Vander Weele
- 10.1515/2161-962X.1004
- 2012
- 2012/08/08
Nov 19, 2020 · Unlike confounding, whose effects we want to get rid of in our analysis, effect modification is an interesting finding in and of itself, and we report it. To check for effect modification, conduct a stratified analysis.
EFFECT MODIFICATION. Epidemiologists apply the term “effect modification” to indicate that the effect of one variable on another varies across strata of a third. There are many different measures of effect and, thus many different measures by which a variable may be an effect modifier for the relationship between a cause and an effect.
