PMID: 8470668Mar 15, 1993Paper

Representative and misrepresentative associations of birth defects in livebirths. Conditions under which relative risks greater than unity in livebirths necessarily imply relative risks greater than unity in all conceptuses

American Journal of Epidemiology
E B Hook, R R Regal

Abstract

One may express the relative risk of defect in all conceptuses, r(def), as a function of the relative risk of defect in livebirths, r(def,lb), and in embryonic and fetal deaths, r(def,efd), as r(def) = C(lb)r(def,lb) + C(efd)r(def,efd), where C(lb) and C(efd) are coefficients defined in terms of conceptus and defect viability and lethality. If the relative risk of birth defect in livebirths, r(def,lb), is greater than unity, but the relative risk of defect in all conceptuses, r(def), is equal to or less than unity (or the reverse pattern holds), then the relative risk of defects in livebirths may be said to be "distorting" or "misrepresentative" because it does not reflect the nature of the association in all conceptuses. The authors define and present an explicit expression for a boundary upon the relative risk of defect in livebirths. If the relative risk of defect in livebirths is (validly) greater than this boundary value, then the relative risk in all conceptuses must be greater than unity and the observed relative risk of defect in births is "representative" and not distorting. The authors show that the boundary value is equal to 1/C(lb), where C(lb) is a simple function of the lethality of all unexposed conceptuses, the ...Continue Reading

Citations

Feb 28, 2002·Clinical Obstetrics and Gynecology·Gerald G Briggs
Apr 7, 2020·Paediatric and Perinatal Epidemiology·Dominique HeinkeUNKNOWN National Birth Defects Prevention Study
Apr 24, 2010·Journal of Travel Medicine·Urban Hellgren, Lars Rombo

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