Interpretation and Potential Biases of Mendelian Randomization Estimates With Time-Varying Exposures.
Am J Epidemiol
; 188(1): 231-238, 2019 01 01.
Article
em En
| MEDLINE
| ID: mdl-30239571
ABSTRACT
Mendelian randomization (MR) is used to answer a variety of epidemiologic questions. One stated advantage of MR is that it estimates a "lifetime effect" of exposure, though this term remains vaguely defined. Instrumental variable analysis, on which MR is based, has focused on estimating the effects of point or time-fixed exposures rather than "lifetime effects." Here we use an empirical example with data from the Rotterdam Study (Rotterdam, the Netherlands, 2009-2013) to demonstrate how confusion can arise when estimating "lifetime effects." We provide one possible definition of a lifetime effect the average change in outcome measured at time t when the entire exposure trajectory from conception to time t is shifted by 1 unit. We show that MR only estimates this type of lifetime effect under specific conditions-for example, when the effect of the genetic variants used on exposure does not change over time. Lastly, we simulate the magnitude of bias that would result in realistic scenarios that use genetic variants with effects that change over time. We recommend that investigators in future MR studies carefully consider the effect of interest and how genetic variants whose effects change with time may impact the interpretability and validity of their results.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Causalidade
/
Análise da Randomização Mendeliana
Tipo de estudo:
Clinical_trials
Limite:
Humans
Idioma:
En
Revista:
Am J Epidemiol
Ano de publicação:
2019
Tipo de documento:
Article
País de afiliação:
Holanda