The Principles of Systematic Effect Modification (PRISEM) framework is a methodical and practical approach by which a researcher can further explore the root causes of population level issues. Borrowing from the discipline of epidemiology, this framework can be viewed as complementary to the epidemiological triad model. The technique of effect modification (moderation) is not new (process outlined here aligns with traditional effect modification technique used by statisticians and epidemiologists), but the specific method of organizing research is novel. The acronym itself is meant to evoke the concept how a prism divides light into the colors of the spectrum. Similar to an actual prism, the PRISEM framework helps to bring to focus and solve each part of the problem.
The model is comprised of three tiers. The three major parts of the model are as follows: social or chronic factors, disease condition, and health outcome. The "social or chronic factors" can be an environmental hazard or social factor such as ethnicity (a social rather than biological construct). Understanding the nature of the "chronic factor" is important to fully understand the impact of the effect modifier. Small but cumulative effects can combine to result in long-term health consequences. The middle factor is the "disease condition" which, in this example, is cardiovascular disease. However, in this model, this condition can be replaced with other conditions like asthma, dementia, or chronic kidney disease. Finally, in the bottom category, any health outcome (e.g. morbidity or mortality) can be considered. This is an important way through with social principles from the social determinants of health and/or equity principles can culminate to improve the overall health of the population.
As an extension, in the classic sense moderation is the easiest to implement and described through the PRISEM approach. The effect is not always the same from the third tier as there are enhancing effects, buffering effects, or antagonistic effects. However, it is important to recognize this as one of the most important out of several process analysis techniques. Creatively one can be thinking about other variations of the third tier of the PRISEM model through the moderation/mediation presentation link. You can follow some of the theory in this White Paper link.
Varied third tier relationships (exposure/predictor/independent variables):
Effect Modification: Separate exposure effects according to another variable (PRISEM model)
Moderation: Separate exposure effects according to another variable (PRISEM model) (usually described in contrast to mediation and answers When? there is a relationship)
Mediation: Evaluate indirect and direct effects of exposures. (usually described in contrast to moderation and answers How?/Why? there is a relationship)
Interaction: Evaluate individual and joint effect of exposure and another variable. Sometimes used broadly.
Confounding: Evaluate another variable that distorts the effect of the exposure.
The PRISEM Framework © 2021 by Sri Banerjee is licensed under CC BY-NC 4.0