Abstract:
BACKGROUND:The initial vanguard cohort of the U.S. National Children's Study was a pregnancy and birth cohort study that sought to enroll some women prior to pregnancy, and to assess exposures early in pregnancy. METHODS:During the recruitment phase (2009-2010), geographically based sampling was used to recruit women early in pregnancy and women not currently pregnant, not using contraception and heterosexually active. We assessed the following outcomes for women enrolled preconception and early in pregnancy: yield of births; demographic characteristics of births for different enrollment groups; time to pregnancy for preconception women; and the timing of study visits for exposure assessment. RESULTS:1399 women were recruited into the initial vanguard cohort: 429 preconception (198 trying for pregnancy, and 231 not trying) and 970 already pregnant. There were 1135 pregnancies (81% of women) and 922 newborns enrolled (81% of pregnancies) through September 2012. Preconception women represented 30.6% of women enrolled, and contributed 14.5% of births. Among women who gave birth, and who had enrolled preconception trying for pregnancy, 67.3% were white non-Hispanic, compared to 50.0% of preconception women not trying for pregnancy, and 61.5% of pregnant women. Women enrolled preconception who were trying for pregnancy had higher cumulative probability of pregnancy at one year compared to women not trying (adjusted 86% versus 56%). Of 165 women enrolled preconception who became pregnant, 19% had a study visit within 30 days of conception. By 10.5 weeks after conception, 75% of women enrolled preconception had completed a pregnancy study visit; for women enrolled pregnant, the 75% threshold was reached at 28.4 weeks. CONCLUSIONS:There were demographic differences in births from women enrolled preconception trying for pregnancy, preconception not trying for pregnancy, or during pregnancy. Time to pregnancy was shorter for women actively trying for pregnancy. Most women enrolled preconception did not have exposure assessment within 30 days of conception, but they did have exposure assessment much earlier during pregnancy than women who enrolled during pregnancy.
journal_name
BMC Med Res Methodoljournal_title
BMC medical research methodologyauthors
Stanford JB,Brenner R,Fetterer D,Palmer L,Schoendorf KC,U.S. National Children’s Study.doi
10.1186/s12874-015-0067-1subject
Has Abstractpub_date
2015-09-24 00:00:00pages
75issn
1471-2288pii
10.1186/s12874-015-0067-1journal_volume
15pub_type
杂志文章abstract:BACKGROUND:Multiple Imputation as usually implemented assumes that data are Missing At Random (MAR), meaning that the underlying missing data mechanism, given the observed data, is independent of the unobserved data. To explore the sensitivity of the inferences to departures from the MAR assumption, we applied the meth...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/1471-2288-12-73
更新日期:2012-06-08 00:00:00
abstract:BACKGROUND:The purpose of this study was to determine the standard tasks performed by clinical research coordinators (CRCs) in oncology clinical trials. METHODS:Forty-one CRCs were anonymously surveyed, using a four-page self-administered questionnaire focused on demographics, qualifications, and professional experien...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/1471-2288-4-6
更新日期:2004-03-25 00:00:00
abstract:BACKGROUND:The health regulatory focus is an application of Higgins' regulatory focus theory to a health-specific context. It explains individual differences in health motivation, strategies, and behavior. Previous research found the Health Regulatory Focus Scale (HRFS) to be a reliable and valid measure for the constr...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/s12874-020-00927-x
更新日期:2020-03-02 00:00:00
abstract:BACKGROUND:The study design and protocol that underpin a randomised controlled trial (RCT) are critical for the ultimate success of the trial. Although RCTs are considered the gold standard for research, there are multiple threats to their validity such as participant recruitment and retention, identifying a meaningful...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/s12874-019-0772-2
更新日期:2019-06-18 00:00:00
abstract:BACKGROUND:Multiple imputation is frequently used to deal with missing data in healthcare research. Although it is known that the outcome should be included in the imputation model when imputing missing covariate values, it is not known whether it should be imputed. Similarly no clear recommendations exist on: the util...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/s12874-016-0281-5
更新日期:2017-01-09 00:00:00
abstract:BACKGROUND:The Pathobiology of Prediabetes in A Biracial Cohort study is a prospective evaluation of the transition from normal to impaired glucose regulation among African American and Caucasian adults with parental type 2 diabetes. This report describes recruitment strategies and relative yields for the 376 enrolled ...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/1471-2288-13-64
更新日期:2013-05-10 00:00:00
abstract:BACKGROUND:Predicting survival of recipients after liver transplantation is regarded as one of the most important challenges in contemporary medicine. Hence, improving on current prediction models is of great interest.Nowadays, there is a strong discussion in the medical field about machine learning (ML) and whether it...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/s12874-020-01153-1
更新日期:2020-11-16 00:00:00
abstract:BACKGROUND:We demonstrate an application of Group-Based Trajectory Modeling (GBTM) based on the beta distribution. It is offered as an alternative to the normal distribution for modeling continuous longitudinal data that are poorly fit by the normal distribution even with censoring. The primary advantage of the beta di...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/s12874-018-0620-9
更新日期:2018-11-26 00:00:00
abstract:BACKGROUND:Postal questionnaires are widely used to collect outcome data on participants. However, a poor response to questionnaires will reduce the statistical power of the study and may introduce bias. A meta analysis of ten trials offering study results, largely in the fields of education and marketing, was shown to...
journal_title:BMC medical research methodology
pub_type: 杂志文章,随机对照试验
doi:10.1186/1471-2288-5-34
更新日期:2005-10-26 00:00:00
abstract:BACKGROUND:The Computer Adaptive Test version of the Community Reintegration of Injured Service Members measure (CRIS-CAT) consists of three scales measuring Extent of, Perceived Limitations in, and Satisfaction with community integration. The CRIS-CAT was developed using item response theory methods. The purposes of t...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/1471-2288-12-145
更新日期:2012-09-17 00:00:00
abstract:BACKGROUND:One of the biggest challenges for population health studies is the recruitment of participants. Questions that investigators have asked are "who volunteers for studies?" and "does recruitment method influence characteristics of the samples?" The purpose of this paper was to compare sample characteristics of ...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/1471-2288-13-149
更新日期:2013-12-06 00:00:00
abstract:BACKGROUND:Randomized controlled trials are the gold-standard for clinical trials. However, randomization is not always feasible. In this article we propose a prospective and adaptive matched case-control trial design assuming that a control group already exists. METHODS:We propose and discuss an interim analysis step...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/s12874-019-0763-3
更新日期:2019-07-16 00:00:00
abstract:BACKGROUND:Technical advances following the Human Genome Project revealed that high-quality and -quantity DNA may be obtained from whole saliva samples. However, usability of previously collected samples and the effects of environmental conditions on the samples during collection have not been assessed in detail. In fi...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/1471-2288-11-170
更新日期:2011-12-19 00:00:00
abstract:BACKGROUND:The Template for Intervention Description and Replication (TIDieR) checklist and guide was developed by an international team of experts to promote full and accurate description of trial interventions. It is now widely used in health research. The aim of this paper is to describe the experience of using TIDi...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/s12874-017-0461-y
更新日期:2018-01-18 00:00:00
abstract:BACKGROUND:The occurrence of communicable diseases (CD) depends on exposure to contagious persons. The effects of exposure to CD are delayed in time and contagious persons remain contagious for several days during which their contagiousness varies. Moreover when multiple exposures occur, it is difficult to know which e...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/1471-2288-13-26
更新日期:2013-02-20 00:00:00
abstract:BACKGROUND:Patient-reported outcome (PRO) measures play a key role in the advancement of patient-centered care research. The accuracy of inferences, relevance of predictions, and the true nature of the associations made with PRO data depend on the validity of these measures. Errors inherent to self-report measures can ...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/s12874-016-0161-z
更新日期:2016-05-26 00:00:00
abstract:BACKGROUND:Evidence syntheses, and in particular systematic reviews (SRs), have become one of the cornerstones of evidence-based health care. The Assessment of Multiple Systematic Reviews (AMSTAR) tool has become the most widely used tool for investigating the methodological quality of SRs and is currently undergoing r...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/s12874-016-0183-6
更新日期:2016-08-26 00:00:00
abstract:BACKGROUND:Outcomes collected in randomized clinical trials are observations of random variables that should be independent and identically distributed. However, in some trials, the patients are randomized more than once thus violating both of these assumptions. The probability of an event is not always the same when a...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/1471-2288-5-17
更新日期:2005-05-10 00:00:00
abstract:BACKGROUND:Greater transparency, including sharing of patient-level data for further research, is an increasingly important topic for organisations who sponsor, fund and conduct clinical trials. This is a major paradigm shift with the aim of maximising the value of patient-level data from clinical trials for the benefi...
journal_title:BMC medical research methodology
pub_type: 信件
doi:10.1186/s12874-016-0170-y
更新日期:2016-07-08 00:00:00
abstract:BACKGROUND:Network meta-analysis can be used to combine results from several randomized trials involving more than two treatments. Potential inconsistency among different types of trial (designs) differing in the set of treatments tested is a major challenge, and application of procedures for detecting and locating inc...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/1471-2288-14-61
更新日期:2014-05-10 00:00:00
abstract:BACKGROUND:Estimating the incidence of medical conditions using claims data often requires constructing a prevalence period that predates an event of interest, for instance the diagnosis of cancer, to exclude those with pre-existing conditions from the incidence risk set. Those conditions missed during the prevalence p...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/1471-2288-13-32
更新日期:2013-03-06 00:00:00
abstract:BACKGROUND:Joint models of longitudinal and time-to-event data are increasingly used to perform individual dynamic prediction of a risk of event. However the difficulty to perform inference in nonlinear models and to calculate the distribution of individual parameters has long limited this approach to linear mixed-effe...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/s12874-017-0382-9
更新日期:2017-07-17 00:00:00
abstract:BACKGROUND:How overall physical activity relates to specific activities and how reported activity changes over time may influence interpretation of observed associations between physical activity and health. We examine the relationships between various physical activities self-reported at different times in a large coh...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/1471-2288-11-97
更新日期:2011-06-22 00:00:00
abstract:BACKGROUND:The Community Reintegration of Service Members (CRIS) is a new measure of community reintegration developed to measure veteran's participation in life roles. It consists of three sub-scales: Extent of Participation (Extent), Perceived Limitations with Participation (Perceived), and Satisfaction with Particip...
journal_title:BMC medical research methodology
pub_type: 杂志文章,随机对照试验
doi:10.1186/1471-2288-11-98
更新日期:2011-06-25 00:00:00
abstract:BACKGROUND:The prevailing view in therapeutic clinical research today is that observational studies are useful for generating new hypotheses and that controlled experiments (i.e., randomized clinical trials, RCTs) are the most appropriate method for assessing and confirming the efficacy of interventions. DISCUSSION:Th...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/1471-2288-11-57
更新日期:2011-04-25 00:00:00
abstract:BACKGROUND:Variation in counts between subjects at a given speed or work rate are the most important source of error in physical activity (PA) measurements with accelerometers. The aim of this study was to explore how the use of individual accelerometer cut points (ICPs) affected the analysis of PA field data. METHODS...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/1471-2288-12-172
更新日期:2012-11-15 00:00:00
abstract:BACKGROUND:To provide empirical evidence about prevalence, reporting and handling of missing outcome data in systematic reviews with network meta-analysis and acknowledgement of their impact on the conclusions. METHODS:We conducted a systematic survey including all published systematic reviews of randomized controlled...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/s12874-018-0576-9
更新日期:2018-10-24 00:00:00
abstract:BACKGROUND:Studies examining incident heart failure (HF) have been limited to select populations. To examine incident HF with broader generalizability, there is need to assemble a HF-free cohort using a geographically-diverse sample. We aimed to develop and validate a simple medication-based strategy for assembling a H...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/s12874-019-0890-x
更新日期:2020-03-04 00:00:00
abstract:BACKGROUND:Information and theory beyond copula concepts are essential to understand the dependence relationship between several marginal covariates distributions. In a therapeutic trial data scheme, most of the time, censoring occurs. That could lead to a biased interpretation of the dependence relationship between ma...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/s12874-017-0305-9
更新日期:2017-02-15 00:00:00
abstract:BACKGROUND:While randomised controlled trials (RCTs) provide high-quality evidence to guide practice, much routine care is not based upon available RCTs. This disconnect between evidence and practice is not sufficiently well understood. This case study explores this relationship using a novel approach. Better understan...
journal_title:BMC medical research methodology
pub_type: 杂志文章
doi:10.1186/s12874-020-01009-8
更新日期:2020-05-12 00:00:00