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General Departmental Seminar Series

Potential risk reversal due to heterogeneity

David Oakes
Department of Biostatistics and Computational Biology
University of Rochester


Wednesday, October 17, 2007
12:00 pm
5275 MSC



Prompted by unexpected results from a study of the influence of coronary disease-related
genotypes on recurrent cardiac events among patients whom had already experienced a
myocardial infarction, we consider the potential for risk reversal due to selection in a
heterogeneous population. We discuss two possible mechanisms, frailty selection
and frailty enrichment. Under a simple frailty enrichment model in which the total risk
for an event is the sum of an observed and an unobserved component, we show that
among those who have experienced a first event, those with the higher observed risk
may be at lower risk of a second event, even if, at an individual level, the risks for the
second event are the same as those for the first event.

Reference: Oakes, D. (2006). On potential risk reversal due to heterogeneity.
Student. 5, pp. 205-210

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