Browsing by Subject "Epidemiologic Studies"

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    Gestational age modifies the association between exposure to fine particles and fetal death: findings from a nationwide epidemiological study in the contiguous United States.
    (Environmental health : a global access science source, 2023-09) Tong, Mingkun; Lin, Weiwei; Liu, Hengyi; Gong, Jicheng; Zhang, Junfeng Jim; Xue, Tao

    Backgrounds

    The vulnerability of fetuses differs at different developmental stages, in response to environmental stressors such as fine particulate matter (PM2.5), a ubiquitous air pollutant. Whether gestational age (GA) modifies the association between prenatal fine particulate matter (PM2.5) exposure and fetal death remains unclear.

    Methods

    We selected approximately 47.8 million eligible United States (US) livebirth and fetal death (defined as a termination at a GA of 20-43 weeks) records from 1989 to 2004. For each record, we took the level of prenatal exposure to PM2.5 as the average concentration in the mother's residential county during the entire gestational period, or a specific trimester (i.e., GA-specific exposure), according to well-established estimates of monthly levels across the contiguous US. First, we evaluated the associations between PM2.5 exposure and fetal death at a specific GA (i.e., GA-specific outcome) using five different logit models (unadjusted, covariate-adjusted, propensity-score, double robust, and diagnostic-score models). Double robust model was selected as the main model due to its advantages in causal inference. Then, we conducted meta-analyses to pool the estimated GA-specific associations, and explored how the pooled estimates varied with GA.

    Results

    According to the meta-analysis, all models suggested gestational PM2.5 exposure was associated with fetal death. However, there was slight heterogeneity in the estimated effects, as different models revealed a range of 3.6-10.7% increase in the odds of fetal death per 5-µg/m3 increment of PM2.5. Each 5-µg/m3 increase in PM2.5 exposure during the entire gestation period significantly increased the odds of fetal death, by 8.1% (95% confidence interval [CI]: 5.1-11.2%). In terms of GA-specific outcomes, the odds of fetal death at a GA of 20-27, 28-36, or ≥ 37 weeks increased by 11.0% (5.9-16.4%), 5.2% (0.4-10.1%), and 8.3% (2.5-14.5%), respectively. In terms of GA-specific exposure, the odds of fetal death increased by 6.0% (3.9-8.2%), 4.1% (3.9-8.2%), and 4.3% (0.5-8.2%) with 5-µg/m3 increases in PM2.5 exposure during the first, second, and third trimester, respectively. The association had the largest effect size (odds ratio = 1.098, 95% CI: 1.061-1.137) between PM2.5 exposure during early gestation (i.e., first trimester) and early fetal death (i.e., 20-27 weeks).

    Conclusions

    Prenatal exposure to PM2.5 was significantly associated with an increased risk of fetal death. The association was varied by gestational-age-specific exposures or outcomes, suggesting gestation age as a potential modifier on the effect of PM2.5. The fetus was most vulnerable during the early stage of development to death associated with PM2.5 exposure.
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    Methodologic and statistical approaches to studying human fertility and environmental exposure.
    (Environ Health Perspect, 2004-01) Tingen, Candace; Stanford, Joseph B; Dunson, David B
    Although there has been growing concern about the effects of environmental exposures on human fertility, standard epidemiologic study designs may not collect sufficient data to identify subtle effects while properly adjusting for confounding. In particular, results from conventional time to pregnancy studies can be driven by the many sources of bias inherent in these studies. By prospectively collecting detailed records of menstrual bleeding, occurrences of intercourse, and a marker of ovulation day in each menstrual cycle, precise information on exposure effects can be obtained, adjusting for many of the primary sources of bias. This article provides an overview of the different types of study designs, focusing on the data required, the practical advantages and disadvantages of each design, and the statistical methods required to take full advantage of the available data. We conclude that detailed prospective studies allowing inferences on day-specific probabilities of conception should be considered as the gold standard for studying the effects of environmental exposures on fertility.
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    Phylodynamic inference for structured epidemiological models.
    (PLoS Comput Biol, 2014-04) Rasmussen, David A; Volz, Erik M; Koelle, Katia
    Coalescent theory is routinely used to estimate past population dynamics and demographic parameters from genealogies. While early work in coalescent theory only considered simple demographic models, advances in theory have allowed for increasingly complex demographic scenarios to be considered. The success of this approach has lead to coalescent-based inference methods being applied to populations with rapidly changing population dynamics, including pathogens like RNA viruses. However, fitting epidemiological models to genealogies via coalescent models remains a challenging task, because pathogen populations often exhibit complex, nonlinear dynamics and are structured by multiple factors. Moreover, it often becomes necessary to consider stochastic variation in population dynamics when fitting such complex models to real data. Using recently developed structured coalescent models that accommodate complex population dynamics and population structure, we develop a statistical framework for fitting stochastic epidemiological models to genealogies. By combining particle filtering methods with Bayesian Markov chain Monte Carlo methods, we are able to fit a wide class of stochastic, nonlinear epidemiological models with different forms of population structure to genealogies. We demonstrate our framework using two structured epidemiological models: a model with disease progression between multiple stages of infection and a two-population model reflecting spatial structure. We apply the multi-stage model to HIV genealogies and show that the proposed method can be used to estimate the stage-specific transmission rates and prevalence of HIV. Finally, using the two-population model we explore how much information about population structure is contained in genealogies and what sample sizes are necessary to reliably infer parameters like migration rates.
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    Psychotic experiences and risk of death in the general population: 24-27 year follow-up of the Epidemiologic Catchment Area study.
    (The British journal of psychiatry : the journal of mental science, 2015-07) Sharifi, Vandad; Eaton, William W; Wu, Li Tzy; Roth, Kimberly B; Burchett, Bruce M; Mojtabai, Ramin
    Psychotic experiences are common in the general population and are associated with adverse psychiatric and social outcomes, even in the absence of a psychotic disorder.To examine the association between psychotic experiences and mortality over a 24-27 year period.We used data on 15 049 adult participants from four sites of the Epidemiologic Catchment Area baseline survey in the USA in the early 1980s, linked to the National Death Index and other sources of vital status up until 2007. Psychotic experiences were assessed by the Diagnostic Interview Schedule.Lifetime psychotic experiences at baseline (n = 855; weighted prevalence, 5.5%) were significantly associated with all-cause mortality at follow-up after adjustment for sociodemographic characteristics and psychiatric diagnoses, including schizophrenia spectrum disorders (P<0.05). Baseline psychotic experiences were associated with over 5 years' shorter median survival time. Among the underlying causes of death, suicide had a particularly high hazard ratio (9.16, 95% CI 3.19-26.29).Future research needs to explore the association of psychotic experiences with physical health and lifestyle factors that may mediate the relationship of psychotic experiences with mortality.
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    Studying human fertility and environmental exposures.
    (Environ Health Perspect, 2004-08) Slama, Rémy; Ducot, Béatrice; Keiding, Niels; Bouyer, Jean
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    Temporal trends in the utilization of vasopressors in intensive care units: an epidemiologic study.
    (BMC pharmacology & toxicology, 2016-05) Thongprayoon, Charat; Cheungpasitporn, Wisit; Harrison, Andrew M; Carrera, Perliveh; Srivali, Narat; Kittamongkolchai, Wonngarm; Erdogan, Aysen; Kashani, Kianoush B

    Background

    The choice of vasopressor use in the intensive care unit (ICU) depends primarily on provider preference. This study aims to describe the rate of vasopressor utilization and the trends of each vasoactive agent usage in the ICU over the span of 7 years in a tertiary referral center.

    Methods

    All adult ICU admissions, including medical, cardiac, and surgical ICUs from January 1st, 2007 through December 31st, 2013 were included in this study. Vasopressor use was defined as the continuous intravenous administration of epinephrine, norepinephrine, phenylephrine, dopamine, or vasopressin within a given ICU day. The vasopressor utilization index (VUI) was defined as the proportion of ICU days on each vasoactive agent divided by the total ICU days with vasopressor usage.

    Results

    During the study period, 72,005 ICU admissions and 272,271 ICU days were screened. Vasopressors were used in 19,575 ICU admissions (27 %) and 59,811 ICU days (22 %). Vasopressin was used in 24,496 (41 %), epinephrine in 23,229 (39 %), norepinephrine in 20,648 (34 %), dopamine in 9449 (16 %), and phenylephrine in 7508 (13 %) ICU days. The VUInorepinephrine increased from 0.24 in 2007 to 0.46 in 2013 and VUIphenylephrine decreased from 0.20 in 2007 to 0.08 in 2013 (p < 0.001 both). For epinephrine, dopamine, and vasopressin VUI did not change over the course of study.

    Conclusion

    Vasopressors were used in about one fourth of ICU admissions and about one-fifth of ICU days. Although vasopressin is the most commonly used vasopressor, the use of norepinephrine found to have an increasing trajectory.
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    The use of the case-crossover design in studying illicit drug use.
    (Substance use & misuse, 2000-05) Wu, LT; Anthony, JC
    The case-crossover design was developed to study time-varying exposures that cause transient excess risk of acute health events. It is a variant of case-control and subject-as-own-control research designs, involving use of information about exposure history of each case to estimate the transient effect. This kind of self-control design can help to reduce sampling bias otherwise introduced in the selection of controls, as well as confounding bias that might be derived from enduring individual characteristics, especially personality traits and other long-standing inherited or acquired vulnerabilities. When the subject is used as his or her own control, these personal vulnerabilities are matched. In this paper we discuss strengths and weaknesses of the case-crossover design and suggest applications of the case-crossover design in epidemiologic studies on suspected hazards of illicit drug use, and in studies of drug use and co-occurring psychiatric disturbances. We conclude that the case-crossover design can play a useful role, but it discloses a need to secure fine-grained measurements in epidemiologic research on psychiatric comorbidity. As explained in the paper, we also believe the case-crossover method may be of use to criminologists who study the drugs-crime nexus, to services researchers and clinicians who seek to understand treatment entry and compliance behavior, and to etiologists interested in polydrug use.