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1.
Diabetes Care ; 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31601636

RESUMO

OBJECTIVE: Maternal gestational diabetes mellitus (GDM) has been associated with adverse outcomes in the offspring. Growing evidence suggests that the epigenome may play a role, but most previous studies have been small and adjusted for few covariates. The current study meta-analyzed the association between maternal GDM and cord blood DNA methylation in the Pregnancy and Childhood Epigenetics (PACE) consortium. RESEARCH DESIGN AND METHODS: Seven pregnancy cohorts (3,677 mother-newborn pairs [317 with GDM]) contributed results from epigenome-wide association studies, using DNA methylation data acquired by the Infinium HumanMethylation450 BeadChip array. Associations between GDM and DNA methylation were examined using robust linear regression, with adjustment for potential confounders. Fixed-effects meta-analyses were performed using METAL. Differentially methylated regions (DMRs) were identified by taking the intersection of results obtained using two regional approaches: comb-p and DMRcate. RESULTS: Two DMRs were identified by both comb-p and DMRcate. Both regions were hypomethylated in newborns exposed to GDM in utero compared with control subjects. One DMR (chr 1: 248100345-248100614) was located in the OR2L13 promoter, and the other (chr 10: 135341870-135342620) was located in the gene body of CYP2E1. Individual CpG analyses did not reveal any differentially methylated loci based on a false discovery rate-adjusted P value threshold of 0.05. CONCLUSIONS: Maternal GDM was associated with lower cord blood methylation levels within two regions, including the promoter of OR2L13, a gene associated with autism spectrum disorder, and the gene body of CYP2E1, which is upregulated in type 1 and type 2 diabetes. Future studies are needed to understand whether these associations are causal and possible health consequences.

2.
Environ Health Perspect ; 127(5): 57012, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-31148503

RESUMO

BACKGROUND: Prenatal exposure to air pollution has been associated with childhood respiratory disease and other adverse outcomes. Epigenetics is a suggested link between exposures and health outcomes. OBJECTIVES: We aimed to investigate associations between prenatal exposure to particulate matter (PM) with diameter [Formula: see text] ([Formula: see text]) or [Formula: see text] ([Formula: see text]) and DNA methylation in newborns and children. METHODS: We meta-analyzed associations between exposure to [Formula: see text] ([Formula: see text]) and [Formula: see text] ([Formula: see text]) at maternal home addresses during pregnancy and newborn DNA methylation assessed by Illumina Infinium HumanMethylation450K BeadChip in nine European and American studies, with replication in 688 independent newborns and look-up analyses in 2,118 older children. We used two approaches, one focusing on single cytosine-phosphate-guanine (CpG) sites and another on differentially methylated regions (DMRs). We also related PM exposures to blood mRNA expression. RESULTS: Six CpGs were significantly associated [false discovery rate (FDR) [Formula: see text]] with prenatal [Formula: see text] and 14 with [Formula: see text] exposure. Two of the [Formula: see text] CpGs mapped to FAM13A (cg00905156) and NOTCH4 (cg06849931) previously associated with lung function and asthma. Although these associations did not replicate in the smaller newborn sample, both CpGs were significant ([Formula: see text]) in 7- to 9-y-olds. For cg06849931, however, the direction of the association was inconsistent. Concurrent [Formula: see text] exposure was associated with a significantly higher NOTCH4 expression at age 16 y. We also identified several DMRs associated with either prenatal [Formula: see text] and or [Formula: see text] exposure, of which two [Formula: see text] DMRs, including H19 and MARCH11, replicated in newborns. CONCLUSIONS: Several differentially methylated CpGs and DMRs associated with prenatal PM exposure were identified in newborns, with annotation to genes previously implicated in lung-related outcomes. https://doi.org/10.1289/EHP4522.

3.
JAMA ; 321(17): 1702-1715, 2019 05 07.
Artigo em Inglês | MEDLINE | ID: mdl-31063572

RESUMO

Importance: Both low and high gestational weight gain have been associated with adverse maternal and infant outcomes, but optimal gestational weight gain remains uncertain and not well defined for all prepregnancy weight ranges. Objectives: To examine the association of ranges of gestational weight gain with risk of adverse maternal and infant outcomes and estimate optimal gestational weight gain ranges across prepregnancy body mass index categories. Design, Setting, and Participants: Individual participant-level meta-analysis using data from 196 670 participants within 25 cohort studies from Europe and North America (main study sample). Optimal gestational weight gain ranges were estimated for each prepregnancy body mass index (BMI) category by selecting the range of gestational weight gain that was associated with lower risk for any adverse outcome. Individual participant-level data from 3505 participants within 4 separate hospital-based cohorts were used as a validation sample. Data were collected between 1989 and 2015. The final date of follow-up was December 2015. Exposures: Gestational weight gain. Main Outcomes and Measures: The main outcome termed any adverse outcome was defined as the presence of 1 or more of the following outcomes: preeclampsia, gestational hypertension, gestational diabetes, cesarean delivery, preterm birth, and small or large size for gestational age at birth. Results: Of the 196 670 women (median age, 30.0 years [quartile 1 and 3, 27.0 and 33.0 years] and 40 937 were white) included in the main sample, 7809 (4.0%) were categorized at baseline as underweight (BMI <18.5); 133 788 (68.0%), normal weight (BMI, 18.5-24.9); 38 828 (19.7%), overweight (BMI, 25.0-29.9); 11 992 (6.1%), obesity grade 1 (BMI, 30.0-34.9); 3284 (1.7%), obesity grade 2 (BMI, 35.0-39.9); and 969 (0.5%), obesity grade 3 (BMI, ≥40.0). Overall, any adverse outcome occurred in 37.2% (n = 73 161) of women, ranging from 34.7% (2706 of 7809) among women categorized as underweight to 61.1% (592 of 969) among women categorized as obesity grade 3. Optimal gestational weight gain ranges were 14.0 kg to less than 16.0 kg for women categorized as underweight; 10.0 kg to less than 18.0 kg for normal weight; 2.0 kg to less than 16.0 kg for overweight; 2.0 kg to less than 6.0 kg for obesity grade 1; weight loss or gain of 0 kg to less than 4.0 kg for obesity grade 2; and weight gain of 0 kg to less than 6.0 kg for obesity grade 3. These gestational weight gain ranges were associated with low to moderate discrimination between those with and those without adverse outcomes (range for area under the receiver operating characteristic curve, 0.55-0.76). Results for discriminative performance in the validation sample were similar to the corresponding results in the main study sample (range for area under the receiver operating characteristic curve, 0.51-0.79). Conclusions and Relevance: In this meta-analysis of pooled individual participant data from 25 cohort studies, the risk for adverse maternal and infant outcomes varied by gestational weight gain and across the range of prepregnancy weights. The estimates of optimal gestational weight gain may inform prenatal counseling; however, the optimal gestational weight gain ranges had limited predictive value for the outcomes assessed.


Assuntos
Índice de Massa Corporal , Ganho de Peso na Gestação , Complicações na Gravidez , Resultado da Gravidez , Adulto , Peso ao Nascer , Cesárea/estatística & dados numéricos , Diabetes Gestacional , Feminino , Humanos , Hipertensão Induzida pela Gravidez , Recém-Nascido , Obesidade , Gravidez , Nascimento Prematuro
4.
J Epidemiol Community Health ; 73(5): 475-480, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30804046

RESUMO

There is debate as to whether cohort studies are valid when they are based on a source population that is non-representative of a given general population. This baseline selection may introduce collider bias if the exposure of interest and some other outcome risk factors affect the probability of being in the source population, thus altering the associations between the exposure and those risk factors. We argue that this mechanism is not specific to 'selected cohorts' and also occurs in 'representative cohorts' due to the selection processes that occur in any population. These selection processes are for example linked to the life status, immigration and emigration, which, in turn, may be affected by environmental and social determinants, lifestyles and genetics. We provide real-world examples of this phenomenon using data on the population of the Piedmont region, Italy. In addition to well-recognised mechanisms, such as shared common causes, the associations between the exposure of interest and the risk factors for the outcome of interest in any source population are potentially shaped by collider bias due to the underlying selection processes. We conclude that, when conducting a cohort study, different source populations, whether 'selected' or 'representative', may lead to different exposure-outcome risk factor associations, and thus different degrees of lack of exchangeability, but that one approach is not inherently more or less biased than the other. The key issue is whether the relevant risk factors can be identified and controlled.

5.
J Med Internet Res ; 20(12): e11046, 2018 12 07.
Artigo em Inglês | MEDLINE | ID: mdl-30530454

RESUMO

BACKGROUND: Web-based questionnaires are increasingly used in epidemiologic studies, as traditional methods are facing a decrease in response rates and an increase in costs. However, few studies have investigated factors related to the level of completion of internet-based epidemiologic questionnaires. OBJECTIVE: Our objective was to identify person-level characteristics and item design factors associated with breakoff (not finishing the questionnaire) and item nonresponse in a Web-based questionnaire. METHODS: This study was a cross-sectional analysis of the baseline questionnaire, applied from 2005 to 2016, of the Italian NINFEA (Nascita e Infanzia: gli Effetti dell'Ambiente) birth cohort. The baseline questionnaire was administered to enrolled women, who could register at any time during pregnancy. We used logistic regression to analyze the influence of person-level factors on questionnaire breakoff, and a logistic multilevel model (first level: items of the questionnaire; second level: sections of the questionnaire; third level: study participants) to analyze the influence of person-level and item design factors on item nonresponse. Since the number of applicable items depended on the respondent's characteristics and breakoff, we used inverse probability weighting to deal with missing by design. RESULTS: Of 5970 women, 519 (8.69%) did not finish the questionnaire. Older age (adjusted odds ratio 1.40, 95% CI 1.05-1.88), lower educational level (adjusted odds ratio [OR] 1.53, 95% CI 1.23-1.90), and earlier stage of pregnancy (adjusted OR 3.01, 95% CI 2.31-3.92) were positively associated with questionnaire breakoff. Of the 1,062,519 applicable items displayed for the participants, 22,831 were not responded to (overall prevalence of item nonresponse 2.15%). Item nonresponse was positively associated with older age (adjusted OR 1.25, 95% CI 1.14-1.38), being in the first trimester of pregnancy (adjusted OR 1.18, 95% CI 1.06-1.31), and lower educational level (adjusted OR 1.23, 95% CI 1.14-1.33). Dropdown menu items (adjusted OR 1.77, 95% CI 1.56-2.00) and items organized in grids (adjusted OR 1.69, 95% CI 1.49-1.91) were positively associated with item nonresponse. CONCLUSIONS: It is important to use targeted strategies to keep participants motivated to respond. Item nonresponse in internet-based questionnaires is affected by person-level and item design factors. Some item types should be limited to reduce item nonresponse.


Assuntos
Coleta de Dados/métodos , Internet/normas , Análise Multinível/métodos , Adulto , Estudos Transversais , Feminino , Humanos , Gravidez , Projetos de Pesquisa , Inquéritos e Questionários
6.
Int J Eat Disord ; 51(8): 842-851, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29722053

RESUMO

OBJECTIVE: This study evaluates associations of maternal eating disorders (bulimia nervosa, anorexia nervosa, and purging behaviors) with infant wheezing and examines the effects of eating disorders on several wheezing determinants. METHOD: We studied 5,150 singletons from the NINFEA birth cohort. Maternal bulimia nervosa and anorexia nervosa diagnoses were ascertained from the questionnaires completed in pregnancy and 6 months after delivery, and were analyzed as: ever diagnosis, only before pregnancy, and during pregnancy. Purging behaviors were assessed for 12 months before or during pregnancy. The associations with wheezing between 6 and 18 months of age were assessed in models adjusted for a priori selected confounders. RESULTS: Children born to mothers with lifetime eating disorders were at an increased risk of developing wheezing (adjusted OR 1.68; [95% CI: 1.08, 2.60]), and this risk further increased when the disorders were active during pregnancy (2.52 [1.23, 5.19]). Increased risk of offspring wheezing was observed also for purging behaviors without history of eating disorder diagnosis (1.50 [1.10, 2.04]). The observed associations were not explained by comorbid depression and/or anxiety. Bulimia nervosa and/or anorexia nervosa during pregnancy were also associated with several risk factors for wheezing, including maternal smoking, adverse pregnancy outcomes, shorter breastfeeding duration, and day-care attendance. DISCUSSION: The associations of maternal eating disorders with offspring wheezing suggest long-term adverse respiratory outcomes in children of mothers with eating disorders. A better understanding of mechanisms implicated is necessary to help reduce the respiratory disease burden in these children.

7.
Epidemiol Prev ; 42(2): 121-126, 2018 Mar-Apr.
Artigo em Italiano | MEDLINE | ID: mdl-29774708

RESUMO

"In March 2016, the website of the NINFEA project (an Internet-based cohort set up to investigate the effects of exposures acting early in life) was enriched with the section «Data¼, which reports aggregated data for selected variables of the cohort. This article discusses the rationale for this new section, available data and their possible uses are described, and some results are compared with figures accessible from surveillance studies. The Italian birth cohort NINFEA includes 7,500 pregnant women, recruited through the Internet from 2005 to June 2016, and of their children, followed up with repeated questionnaires. Thus, the «Data¼ section is based on a selected population. Currently, this new section includes information on maternal lifestyles/characteristics in pregnancy (e.g., alcohol, smoking, use of medications), child health (e.g., obesity, asthma symptoms, growth) and behaviours (e.g., sleeping patterns, being breastfed). Up to December 18th, 2017, its pages were visited 12,620 times. Prevalences for selected variables (e.g., prepregnancy body mass index, breast feeding, infant sleeping position) are similar to those reported by surveillance studies. Aggregated exposure and outcome data from large cohorts can be systematically made publicly available. These data may be of interest to the participants, to population subgroups whose characteristics are similar to the study participants, and to researchers and policy makers, whenever similar data are not available from population-based surveillance systems."

8.
Environ Sci Technol ; 52(9): 5427-5437, 2018 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-29597345

RESUMO

Maternal exposure to airborne particulate matter (PM) has been associated with restricted fetal growth and reduced birthweight. Here, we performed methylome-wide analyses of cord and children's blood DNA in relation to residential exposure to PM smaller than 10 µm (PM10). This study included participants of the Avon Longitudinal Study of Pregnancy and Childhood (ALSPAC, cord blood, n = 780; blood at age 7, n = 757 and age 15-17, n = 850) and the EXPOsOMICS birth cohort consortium including cord blood from ENVIR ONAGE ( n = 197), INMA ( n = 84), Piccolipiù ( n = 99) and Rhea ( n = 75). We could not identify significant CpG sites, by meta-analyzing associations between maternal PM10 exposure during pregnancy and DNA methylation in cord blood, nor by studying DNA methylation and concordant annual exposure at 7 and 15-17 years. The CpG cg21785536 was inversely associated with PM10 exposure using a longitudinal model integrating the three studied age groups (-1.2% per 10 µg/m3; raw p-value = 3.82 × 10-8). Pathway analyses on the corresponding genes of the 100 strongest associated CpG sites of the longitudinal model revealed enriched pathways relating to the GABAergic synapse, p53 signaling and NOTCH1. We provided evidence that residential PM10 exposure in early life affects methylation of the CpG cg21785536 located on the EGF Domain Specific O-Linked N-Acetylglucosamine Transferase gene.

9.
J Proteome Res ; 17(3): 1235-1247, 2018 03 02.
Artigo em Inglês | MEDLINE | ID: mdl-29401400

RESUMO

Birth weight is an important indicator of maternal and fetal health and a predictor of health in later life. However, the determinants of variance in birth weight are still poorly understood. We aimed to identify the biological pathways, which may be perturbed by environmental exposures, that are important in determining birth weight. We applied untargeted mass-spectrometry-based metabolomics to 481 cord blood samples collected at delivery in four birth cohorts from across Europe: ENVIRONAGE (Belgium), INMA (Spain), Piccolipiu (Italy), and Rhea (Greece). We performed a metabolome-wide association scan for birth weight on over 4000 metabolic features, controlling the false discovery rate at 5%. Annotation of compounds was conducted through reference to authentic standards. We identified 68 metabolites significantly associated with birth weight, including vitamin A, progesterone, docosahexaenoic acid, indolelactic acid, and multiple acylcarnitines and phosphatidylcholines. We observed enrichment (p < 0.05) of the tryptophan metabolism, prostaglandin formation, C21-steroid hormone signaling, carnitine shuttle, and glycerophospholipid metabolism pathways. Vitamin A was associated with both maternal smoking and birth weight, suggesting a mediation pathway. Our findings shed new light on the pathways central to fetal growth and will have implications for antenatal and perinatal care and potentially for health in later life.


Assuntos
Peso ao Nascer/fisiologia , Sangue Fetal/química , Desenvolvimento Fetal/fisiologia , Metaboloma , Carnitina/análogos & derivados , Carnitina/sangue , Cromatografia Líquida de Alta Pressão , Estudos de Coortes , Ácidos Docosa-Hexaenoicos/sangue , Exposição Ambiental/análise , Europa (Continente) , Feminino , Feto , Humanos , Indóis/sangue , Recém-Nascido , Masculino , Espectrometria de Massas/métodos , Material Particulado/análise , Fosfatidilcolinas/sangue , Gravidez , Progesterona/sangue , Prostaglandinas/sangue , Padrões de Referência , Triptofano/sangue , Vitamina A/sangue
11.
Int J Epidemiol ; 46(5): 1465-1477, 2017 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-28338907

RESUMO

Background: It has been suggested that prenatal exposure to n-3 long-chain fatty acids protects against asthma and other allergy-related diseases later in childhood. The extent to which fish intake in pregnancy protects against child asthma and rhinitis symptoms remains unclear. We aimed to assess whether fish and seafood consumption in pregnancy is associated with childhood wheeze, asthma and allergic rhinitis. Methods: We pooled individual data from 60 774 mother-child pairs participating in 18 European and US birth cohort studies. Information on wheeze, asthma and allergic rhinitis prevalence was collected using validated questionnaires. The time periods of interest were: infancy (0-2 years), preschool age (3-4 years), and school age (5-8 years). We used multivariable generalized models to assess associations of fish and seafood (other than fish) consumption during pregnancy with child respiratory outcomes in cohort-specific analyses, with subsequent random-effects meta-analyses. Results: The median fish consumption during pregnancy ranged from 0.44 times/week in The Netherlands to 4.46 times/week in Spain. Maternal fish intake during pregnancy was not associated with offspring wheeze symptoms in any age group nor with the risk of child asthma [adjusted meta-analysis relative risk (RR) per 1-time/week = 1.01, 95% confidence interval 0.97-1.05)] and allergic rhinitis at school age (RR = 1.01, 0.99-1.03). These results were consistently found in further analyses by type of fish and seafood consumption and in sensitivity analyses. Conclusion: We found no evidence supporting a protective association of fish and seafood consumption during pregnancy with offspring symptoms of wheeze, asthma and allergic rhinitis from infancy to mid childhood.


Assuntos
Asma/epidemiologia , Ácidos Graxos Ômega-3/administração & dosagem , Fenômenos Fisiológicos da Nutrição Pré-Natal , Rinite Alérgica/epidemiologia , Alimentos Marinhos , Animais , Criança , Pré-Escolar , Estudos de Coortes , Europa (Continente)/epidemiologia , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Gravidez , Prevalência , Análise de Regressão , Sons Respiratórios , Inquéritos e Questionários , Estados Unidos/epidemiologia
12.
Thorax ; 71(12): 1091-1096, 2016 12.
Artigo em Inglês | MEDLINE | ID: mdl-27369356

RESUMO

BACKGROUND: Rapid postnatal weight gain has been associated with wheezing and asthma in children, but it remains unclear whether it acts independently of overweight. We aimed to disentangle the roles of infant's size and weight gain velocity in the development of wheezing in early childhood using a novel method that allows for mutual adjustment for different aspects of growth. METHODS: Data were obtained from the NINFEA questionnaires where weight measurements from birth up to 18 months of age were assessed in 4492 term singletons. Wheezing was defined as at least one episode of wheezing/whistling in the chest occurring between 6 and 18 months of age. The SuperImposition by Translation And Rotation model was used to estimate individual weight trajectories defined by three child-specific parameters: size, velocity and tempo, that is age at peak weight velocity. These parameters were standardised and related to wheezing using logistic regression with effects expressed as an increase of one SD. RESULTS: A median of five weight measurements per child were obtained. Infant size (OR=1.28; 95% CI 1.12 to 1.46) and weight gain velocity (OR=1.30; 95% CI 1.15 to 1.48) were independently positively associated with wheezing. We found no evidence of an effect of tempo on infant wheezing. The estimates were changed only minimally after adjustment for potential confounders. CONCLUSIONS: Faster growth and larger size in the first 18 months of life are both independently associated with an increased risk of wheezing. These findings suggest that early growth patterns play a role in shaping the occurrence of wheezing.


Assuntos
Sons Respiratórios/etiologia , Ganho de Peso/fisiologia , Envelhecimento/fisiologia , Antropometria/métodos , Peso ao Nascer/fisiologia , Peso Corporal/fisiologia , Estudos de Coortes , Feminino , Seguimentos , Humanos , Recém-Nascido , Masculino , Sons Respiratórios/fisiopatologia , Fatores de Risco , Fatores Sexuais
13.
JAMA Pediatr ; 170(4): 381-90, 2016 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-26882542

RESUMO

IMPORTANCE: Maternal fish intake in pregnancy has been shown to influence fetal growth. The extent to which fish intake affects childhood growth and obesity remains unclear. OBJECTIVE: To examine whether fish intake in pregnancy is associated with offspring growth and the risk of childhood overweight and obesity. DESIGN, SETTING, AND PARTICIPANTS: Multicenter, population-based birth cohort study of singleton deliveries from 1996 to 2011 in Belgium, France, Greece, Ireland, Italy, the Netherlands, Norway, Poland, Portugal, Spain, and Massachusetts. A total of 26,184 pregnant women and their children were followed up at 2-year intervals until the age of 6 years. EXPOSURES: Consumption of fish during pregnancy. MAIN OUTCOMES AND MEASURES: We estimated offspring body mass index percentile trajectories from 3 months after birth to 6 years of age. We defined rapid infant growth as a weight gain z score greater than 0.67 from birth to 2 years and childhood overweight/obesity at 4 and 6 years as body mass index in the 85th percentile or higher for age and sex. We calculated cohort-specific effect estimates and combined them by random-effects meta-analysis. RESULTS: This multicenter, population-based birth cohort study included the 26,184 pregnant women and their children. The median fish intake during pregnancy ranged from 0.5 times/week in Belgium to 4.45 times/week in Spain. Women who ate fish more than 3 times/week during pregnancy gave birth to offspring with higher body mass index values from infancy through middle childhood compared with women with lower fish intake (3 times/week or less). High fish intake during pregnancy (>3 times/week) was associated with increased risk of rapid infant growth, with an adjusted odds ratio (aOR) of 1.22 (95% CI, 1.05-1.42) and increased risk of offspring overweight/obesity at 4 years (aOR, 1.14 [95% CI, 0.99-1.32]) and 6 years (aOR, 1.22 [95% CI, 1.01-1.47]) compared with an intake of once per week or less. Interaction analysis showed that the effect of high fish intake during pregnancy on rapid infant growth was greater among girls (aOR, 1.31 [95% CI, 1.08-1.59]) than among boys (aOR, 1.11 [95% CI, 0.92-1.34]; P = .02 for interaction). CONCLUSIONS AND RELEVANCE: High maternal fish intake during pregnancy was associated with increased risk of rapid growth in infancy and childhood obesity. Our findings are in line with the fish intake limit proposed by the US Food and Drug Administration and Environmental Protection Agency.


Assuntos
Dieta , Desenvolvimento Fetal/fisiologia , Peixes , Sobrepeso/etiologia , Obesidade Pediátrica/etiologia , Complicações na Gravidez , Alimentos Marinhos , Animais , Índice de Massa Corporal , Criança , Desenvolvimento Infantil , Pré-Escolar , Estudos de Coortes , Europa (Continente) , Feminino , Seguimentos , Humanos , Lactente , Recém-Nascido , Masculino , Sobrepeso/epidemiologia , Obesidade Pediátrica/epidemiologia , Gravidez , Fatores de Risco , Estados Unidos
14.
Ann Epidemiol ; 25(12): 955-8, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26603127

RESUMO

BACKGROUND: It is common to use nonrepresentative samples in observational epidemiologic studies, but there has been debate about whether this introduces bias. In this article, we consider the consequences on noncollapsibility of a sample selection related to a relevant outcome-risk factor. METHODS: We focused on the odds ratio and defined the noncollapsibility effect as the difference between the marginal and the conditional (with respect to the outcome-risk factor) exposure-outcome association. We consider a situation in which the aims of the study require the estimate of a conditional effect. RESULTS: Using a classical numerical example, which assumes that all variables are binary and that the outcome-risk factor is not an effect modifier, we illustrate that in the selected sample the noncollapsibility effect can either be larger or smaller than in the population-based study, according to whether the selection moves the prevalence of the risk factor closer to or away from 50%. When the outcome-risk factor is also a confounder, the magnitude of the noncollapsibility effect in the selected sample depends on the effects of the selection on both noncollapsibility and confounding. CONCLUSIONS: When a key outcome-risk factor is unmeasured, in presence of noncollapsibility neither a population-based nor a selected study can directly estimate the conditional effect; whether the computable marginal is closer to the conditional in the selected or in the population-based study depends on the underlying population and the selection process.


Assuntos
Pesquisa Biomédica/normas , Confiabilidade dos Dados , Projetos de Pesquisa/normas , Viés de Seleção , Estudos Epidemiológicos , Humanos , Razão de Chances , Fatores de Risco
15.
JMIR Res Protoc ; 4(2): e71, 2015 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-26071071

RESUMO

BACKGROUND: International collaborative cohorts the NINFEA and the ELF studies are mother-child cohorts that use the internet for recruitment and follow-up of their members. The cohorts investigated the association of early life exposures and a wide range of non-communicable diseases. OBJECTIVE: The objective is to report the research methodology, with emphasis on the advantages and limitations offered by an Internet-based design. These studies were conducted in Turin, Italy and Wellington, New Zealand. METHODS: The cohorts utilized various online/offline methods to recruit participants. Pregnant women who became aware volunteered, completed an online questionnaire, thus obtaining baseline information. RESULTS: The NINFEA study has recruited 7003 pregnant women, while the ELF study has recruited 2197 women. The cohorts targeted the whole country, utilizing a range of support processes to reduce the attrition rate of the participants. For the NINFEA and ELF cohorts, online participants were predominantly older (35% and 28.9%, respectively), highly educated (55.6% and 84.9%, respectively), and were in their final trimester of pregnancy (48.5% and 53.6%, respectively). CONCLUSIONS: Internet-based cohort epidemiological studies are feasible, however, it is clear that participants are self-selective samples, as is the case for many birth cohorts. Internet-based cohort studies are potentially cost-effective and novel methodology for conducting long-term epidemiology research. However, from our experience, participants tend to be self-selective. In marked time, if the cohorts are to form part of a larger research program they require further use and exploration to address biases and overcome limitations.

16.
Epidemiol Prev ; 39(1): 14-8, 2015 Jan-Feb.
Artigo em Italiano | MEDLINE | ID: mdl-25855542

RESUMO

In the last decade a new form of participation of the citizens in research activities and in the production of knowledge has emerged.This development has started to reach epidemiological research, as illustrated in the recent section "EpiChange" of the journal Epidemiologia e Prevenzione. The conduction of epidemiological research through the engagement of citizens and new forms of production of knowledge - including peer-production - is still in its infancy. In 2005,we started in Italy a birth cohort, the NINFEA project, which uses the Internet to recruit pregnant women and to follow-up their children. Participants are volunteers who decide to take part in the research project. In this paper, we consider the aspects of the NINFEA project that are consistent with the concept of collaborative production of knowledge. In particular,we discuss issues related to the motivation of the participants, the selection of the research hypotheses to be evaluated and the definition of the population of interest of the study.


Assuntos
Saúde da Criança , Participação da Comunidade , Crowdsourcing , Saúde Ambiental , Bases de Dados Factuais , Feminino , Humanos , Recém-Nascido , Internet , Itália , Estudos Longitudinais , Motivação , Seleção de Pacientes , Gravidez , Projetos de Pesquisa , Apoio à Pesquisa como Assunto , Inquéritos e Questionários
18.
PLoS One ; 9(2): e90291, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24587314

RESUMO

BACKGROUND: Studying prenatal influences of early life growth is relevant to life-course epidemiology as some of its features have been linked to the onset of later diseases. METHODS: We studied the association between prenatal maternal characteristics (height, age, parity, education, pre-pregnancy body mass index (BMI), smoking, gestational diabetes and hypertension) and offspring weight trajectories in infancy using SuperImposition by Translation And Rotation (SITAR) models, which parameterize growth in terms of three biologically interpretable parameters: size, velocity and tempo. We used data from three contemporary cohorts based in Portugal (GXXI, n=738), Italy (NINFEA, n=2,925), and Chile (GOCS, n=959). RESULTS: Estimates were generally consistent across the cohorts for maternal height, age, parity and pre-pregnancy overweight/obesity. Some exposures only affected one growth parameter (e.g. maternal height (per cm): 0.4% increase in size (95% confidence interval (CI):0.3; 0.5)), others were either found to affect size and velocity (e.g. pre-pregnancy underweight vs normal weight: smaller size (-4.9%, 95% CI:-6.5; -3.3), greater velocity (5.9%, 95% CI:1.9;10.0)), or to additionally influence tempo (e.g. pre-pregnancy overweight/obesity vs normal weight: increased size (7.9%, 95% CI:4.9;10.8), delayed tempo (0.26 months, 95% CI:0.11;0.41), decreased velocity (-4.9%, 95% CI: -10.8;0.9)). CONCLUSIONS: By disentangling the growth parameters of size, velocity and tempo, we found that prenatal maternal characteristics, especially maternal smoking, pre-pregnancy overweight and underweight, parity and gestational hypertension, are associated with different aspects of infant weight growth. These results may offer insights into the mechanisms governing infant growth.


Assuntos
Desenvolvimento Infantil , Efeitos Tardios da Exposição Pré-Natal , Adulto , Peso Corporal , Estudos de Coortes , Feminino , Gráficos de Crescimento , Humanos , Lactente , Masculino , Exposição Materna/efeitos adversos , Gravidez , Fatores de Risco , Ganho de Peso , Adulto Jovem
19.
J Allergy Clin Immunol ; 133(5): 1317-29, 2014 May.
Artigo em Inglês | MEDLINE | ID: mdl-24529685

RESUMO

BACKGROUND: Preterm birth, low birth weight, and infant catch-up growth seem associated with an increased risk of respiratory diseases in later life, but individual studies showed conflicting results. OBJECTIVES: We performed an individual participant data meta-analysis for 147,252 children of 31 birth cohort studies to determine the associations of birth and infant growth characteristics with the risks of preschool wheezing (1-4 years) and school-age asthma (5-10 years). METHODS: First, we performed an adjusted 1-stage random-effect meta-analysis to assess the combined associations of gestational age, birth weight, and infant weight gain with childhood asthma. Second, we performed an adjusted 2-stage random-effect meta-analysis to assess the associations of preterm birth (gestational age <37 weeks) and low birth weight (<2500 g) with childhood asthma outcomes. RESULTS: Younger gestational age at birth and higher infant weight gain were independently associated with higher risks of preschool wheezing and school-age asthma (P < .05). The inverse associations of birth weight with childhood asthma were explained by gestational age at birth. Compared with term-born children with normal infant weight gain, we observed the highest risks of school-age asthma in children born preterm with high infant weight gain (odds ratio [OR], 4.47; 95% CI, 2.58-7.76). Preterm birth was positively associated with an increased risk of preschool wheezing (pooled odds ratio [pOR], 1.34; 95% CI, 1.25-1.43) and school-age asthma (pOR, 1.40; 95% CI, 1.18-1.67) independent of birth weight. Weaker effect estimates were observed for the associations of low birth weight adjusted for gestational age at birth with preschool wheezing (pOR, 1.10; 95% CI, 1.00-1.21) and school-age asthma (pOR, 1.13; 95% CI, 1.01-1.27). CONCLUSION: Younger gestational age at birth and higher infant weight gain were associated with childhood asthma outcomes. The associations of lower birth weight with childhood asthma were largely explained by gestational age at birth.


Assuntos
Asma , Peso ao Nascer , Idade Gestacional , Nascimento Prematuro , Ganho de Peso , Asma/epidemiologia , Asma/patologia , Asma/fisiopatologia , Europa (Continente)/epidemiologia , Feminino , Humanos , Lactente , Recém-Nascido , Masculino , Nascimento Prematuro/epidemiologia , Nascimento Prematuro/patologia , Nascimento Prematuro/fisiopatologia , Fatores de Risco
20.
Int J Epidemiol ; 43(2): 632-3, 2014 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-24443500
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