Δευτέρα 6 Ιουνίου 2022

Prenatal Exposure to Insecticides and Weight Trajectories Among South African Children in the VHEMBE Birth Cohort

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imageBackground: Dichlorodiphenyltrichloroethane (DDT) or pyrethroid insecticides are sprayed inside dwellings for malaria vector control, resulting in high exposure to millions of people, including pregnant women. These chemicals disrupt endocrine function and may affect child growth. To our knowledge, few studies have investigated the potential impact of prenatal exposure to DDT or pyrethroids on growth trajectories. Methods: We investigated associations between gestational insecticide exposure and child growth trajectories in the Venda Health Examination of Mothers, Babies and their Environment, a birth cohort of 751 children born between 2012 and 2013 in South Africa. Based on child weight measured at follow-up and abstracted from medical records, we modeled weight trajectories from birth to 5 years using SuperImposition, Translation and Rotation, which estimated two child-specific parameters: size (average weight) and tempo (age at peak weight velocity). We estimated associations between peripartum maternal concentrations of serum DDT, dichlorodiphenyldichloroethylene, or urinary pyrethroid metabolites and SuperImposition, Translation and Rotation parameters using marginal structural models. Results: We observed that a 10-fold increase in maternal concentrations of the pyrethroid metabolite trans-3-(2,2,-dicholorvinyl)-2,2-dimethyl-cyclopropane carboxylic acid was associated with a 21g (95% confidence interval = −40, −1.6) smaller size among boys but found no association among girls (Pinteraction = 0.07). Estimates suggested that pyrethroids may be associated with earlier tempo but were imprecise. We observed no association with serum DDT or dichlorodiphenyldichloroethylene. Conclusions: Inverse associations between pyrethroids and weight trajectory parameters among boys are consistent with hypothesized disruption of androgen pathways and with our previous research in this population, and support the endocrine-disrupting potential of pyrethroids in humans.
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Prenatal Antidepressant Exposure and the Risk of Attention-deficit/Hyperactivity Disorder in Childhood: A Cohort Study With Triangulation

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imageBackground: Uncontrolled confounding from maternal depression and genetic and environmental factors is expected in studies investigating the effect of prenatal antidepressant exposure on the risk of attention-deficit/hyperactivity disorder (ADHD) in childhood and may explain inconsistencies in the existing evidence. We aimed to assess this effect using triangulation. Methods: Using population-based health registries, we conducted a nationwide cohort study of all children born in Denmark between 1997 and 2017 and followed through 2018 for ADHD. We assessed the effect of prenatal antidepressant exposure on the risk of ADHD in childhood by comparing children with and without prenatal antidepressant exposure in terms of adjusted incidence rate ratios (IRRs), adjusted incidence rate differences (IRDs), and adjusted risk differences (RDs) and the associated 95% confidence intervals (CIs). We triangulated results from four different analytic approaches: an overall analysis, a negative control analysis, a sibling analysis, and a former-user analysis. Results: The overall study cohort consisted of 1,253,362 children, among whom 28,910 (2.3%) had prenatal antidepressant exposure. ADHD during follow-up was diagnosed among 1,411 (4.9%) of the exposed and in 37,196 (3.0%) of the unexposed children. Triangulation suggested an IRR of 1.09–1.15; an IRD less than 1 case/1,000 person-years, and an RD of 0.9%–2.2% over an up to 18-year period. Conclusions: Based on triangulation, we estimated a modest effect of prenatal antidepressant exposure on the risk of ADHD in childhood. However, considering the limitations of our approaches, this observed association may be partially due to residual biases. See video abstract at, http://links.lww.com/EDE/B935.
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Use of Recently Vaccinated Individuals to Detect Bias in Test-Negative Case–Control Studies of COVID-19 Vaccine Effectiveness

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imagePostauthorization observational studies play a key role in understanding COVID-19 vaccine effectiveness following the demonstration of efficacy in clinical trials. Although bias due to confounding, selection bias, and misclassification can be mitigated through careful study design, unmeasured confounding is likely to remain in these observational studies. Phase III trials of COVID-19 vaccines have shown that protection from vaccination does not occur immediately, meaning that COVID-19 risk should be similar in recently vaccinated and unvaccinated individuals, in the absence of confounding or other bias. Several studies have used the estimated effectiveness among recently vaccinated individuals as a negative control exposure to detect bias in vaccine effectiveness estimates. In this paper, we introduce a theoretical framework to describe the interpretation of such a bias indicator in test-negative studies, and outline strong assumptions that would allow vaccine effectiveness among recently vaccinated individuals to serve as a negative control exposure.
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Gestational hypertensive disorders and maternal breast cancer risk in a nationwide cohort of 40,720 parous women

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Background: Pre-eclampsia and gestational hypertension are hypothesized to be associated with reduced maternal breast cancer risk, but the epidemiologic evidence is inconclusive. Our objective was to examine associations between gestational hypertensive disorders and breast cancer in a nationwide cohort of women with a family history of breast cancer. Methods: Women ages 35-74 years who had a sister previously diagnosed with breast cancer, but had never had breast cancer themselves, were enrolled in the Sister Study from 2003-2009 (N=50,884). At enrollment, participants reported diagnoses of eclampsia, pre-eclampsia, or gestational hypertension in each pregnancy. We used Cox proportional hazards models to estimate HRs and 95% CIs for the association between history of a gestational hypertensive disorder and incident invasive breast cancer or ductal carcinoma in situ among 40,720 parous women. We used age as the time scale and adjusted for birth cohort, race–ethnicity, and reproductive, socioeconomic, and behavioral factors. We examined effect measure modification by risk factors for gestational hypertensive disease and breast cancer and assessed possible etiologic heterogeneity across tumor characteristics. Results: The prevalence of gestational hypertensive disease was 12%. During follow-up (mean=10.9 years), 3198 eligible women self-reported a breast cancer diagnosis. History of a gestational hypertensive disorder was not associated with breast cancer risk (HR=1.0, 95% CI 0.90, 1.1). We did not observe clear evidence of effect measure modification or etiologic heterogeneity. Conclusions: History of a gestational hypertensive disorder was not associated with breast cancer risk in a cohort of women with a first-degree family history of breast cancer. Copyright © 2022 Wolters Kluwer Health, Inc. All rights reserved.
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