Outcomes of Zika virus infection during pregnancy: contributions to the debate on the efficiency of cohort studies

BMC Public Health

Debate

Leila Posenato Garcia¹  Elisabeth Carmen Duarte²  Wildo Navegantes de Araújo³  Maria P. Velez⁴ 

[1] Institute of Applied Economic Research – IPEA, Brasília, Brazil;Institute of Applied Economic Research – SBS Quadra 1, Bloco J, Ed. BNDES/Ipea, 70076-900, Brasília, DF, Brazil;Medical School, University of Brasilia– UnB, Brasília, Brazil;Núcleo de Medicina Tropical, Campus Universitário Darcy Ribeiro, Asa Norte, Caixa Postal 4517, 70910-900, Brasília, DF, Brazil;Núcleo de Medicina Tropical, Campus Universitário Darcy Ribeiro, Asa Norte, Caixa Postal 4517, 70910-900, Brasília, DF, Brazil;Faculty of Ceilândia, University of Brasília – UnB, Brasília, Brazil;School of Medicine – Department of Obstetrics and Gynaecology, Queen’s University, 99 University Ave, K7L 3N6, Kingston, ON, Canada;

关键词: Zika virus infection, Cohort studies, Efficiency, Pregnancy outcome, Congenital abnormalities, Epidemiologic studies;   

DOI  :  10.1186/s12889-017-4915-2

 received in 2017-08-23, accepted in 2017-11-15,  发布年份 2017

来源: Springer

【 摘 要 】

BackgroundZika infection during pregnancy (ZIKVP) is known to be associated with adverse outcomes. Studies on this matter involve both rare outcomes and rare exposures and methodological choices are not straightforward. Cohort studies will surely offer more robust evidences, but their efficiency must be enhanced. We aim to contribute to the debate on sample selection strategies in cohort studies to assess outcomes associated with ZKVP.Main body of the abstractA study can be statistically more efficient than another if its estimates are more accurate (precise and valid), even if the studies involve the same number of subjects. Sample size and specific design strategies can enhance or impair the statistical efficiency of a study, depending on how the subjects are distributed in subgroups pertinent to the analysis. In most ZIKVP cohort studies to date there is an a priori identification of the source population (pregnant women, regardless of their exposure status) which is then sampled or included in its entirety (census). Subsequently, the group of pregnant women is classified according to exposure (presence or absence of ZIKVP), respecting the exposed:unexposed ratio in the source population. We propose that the sample selection be done from the a priori identification of groups of pregnant women exposed and unexposed to ZIKVP. This method will allow for an oversampling (even 100%) of the pregnant women with ZKVP and a optimized sampling from the general population of pregnant women unexposed to ZIKVP, saving resources in the unexposed group and improving the expected number of incident cases (outcomes) overall.ConclusionWe hope that this proposal will broaden the methodological debate on the improvement of statistical power and protocol harmonization of cohort studies that aim to evaluate the association between Zika infection during pregnancy and outcomes for the offspring, as well as those with similar objectives.

【 授权许可】

CC BY   
© The Author(s). 2017