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Xinyao Ji, Dylan S Small, Charles E Leonard, Sean Hennessy
Cohort studies can be biased by unmeasured confounding. We propose a hybrid ecologic-epidemiologic design called the trend-in-trend design, which requires a strong time-trend in exposure, but is unbiased unless there are unmeasured factors affecting outcome for which there are time-trends in prevalence that are correlated with time-trends in exposure across strata with different exposure trends. Thus, the conditions under which the trend-in-trend study is biased are a subset of those under which a cohort study is biased...
October 20, 2016: Epidemiology
Bertel T Hansen, Kim M Sønderskov, Ida Hageman, Peter T Dinesen, Søren D Østergaard
BACKGROUND: Daylight savings time transitions affect approximately 1.6 billion people worldwide. Prior studies have documented associations between daylight savings time transitions and adverse health outcomes, but it remains unknown whether they also cause an increase in the incidence rate of depressive episodes. This seems likely because daylight savings time transitions affect circadian rhythms, which are implicated in the etiology of depressive disorder. Therefore, we investigated the effects of daylight savings time transitions on the incidence rate of unipolar depressive episodes...
October 20, 2016: Epidemiology
Russell J Brooke, Mirjam Ee Kretzschmar, Volker Hackert, Christian Jpa Hoebe, Peter Fm Teunis, Lance A Waller
We develop a novel approach to study an outbreak of Q fever in 2009 in the Netherlands by combining a human dose-response model with geostatistics prediction to relate probability of infection and associated probability of illness to an effective dose of Coxiella burnetii. The spatial distribution of the 220 notified cases in the at-risk population are translated into a smooth spatial field of dose. Based on these symptomatic cases, the dose-response model predicts a median of 611 asymptomatic infections (95% range 410 to 1,084) for the 220 reported symptomatic cases in the at-risk population; 2...
October 19, 2016: Epidemiology
Charles Poole
No abstract text is available yet for this article.
October 11, 2016: Epidemiology
Katherine Keyes, Sandro Galea
No abstract text is available yet for this article.
October 11, 2016: Epidemiology
Joachim Heinrich, Guo Feng, Mary Jo Trepka
BACKGROUND: Although mercury exposure has been associated with several adverse health effects, the association with childhood asthma is under-investigated. Therefore, we explore the association between mercury and childhood asthma in a population with low mercury levels. METHODS: Mercury levels were measured in blood and urine in 1,056 children aged 5-14 years. In addition to including questions about asthma diagnosis and wheezing, the study measured bronchial hyper-responsiveness and allergic sensitization to common aeroallergens...
October 6, 2016: Epidemiology
Edward Goldstein, Virginia E Pitzer, Justin J O'Hagan, Marc Lipsitch
Risks for disease in some population groups relative to others (relative risks) are usually considered to be consistent over time, though they are often modified by other, non-temporal factors. For infectious diseases, in which overall incidence often varies substantially over time, the patterns of temporal changes in relative risks can inform our understanding of basic epidemiologic questions. For example, recent work suggests that temporal changes in relative risks of infection over the course of an epidemic cycle can both be used to identify population groups that drive infectious disease outbreaks, and help elucidate differences in the effect of vaccination against infection (that is relevant to transmission control) compared with its effect against disease episodes (that reflects individual protection)...
September 28, 2016: Epidemiology
Eric Lavigne, Antonio Gasparrini, David M Stieb, Hong Chen, Abdool S Yasseen, Eric Crighton, Teresa To, Scott Weichenthal, Paul J Villeneuve, Sabit Cakmak, Frances Coates, Mark Walker
BACKGROUND: Daily changes in aeroallergens during pregnancy could trigger early labor, but few investigations have evaluated this issue. This study aimed to investigate the association between exposure to aeroallergens during the week preceding birth and the risk of early delivery among preterm and term pregnancies. METHODS: We identified data on 225,234 singleton births that occurred in six large cities in the province of Ontario, Canada, from 2004 to 2011 (April to October) from a birth registry...
September 28, 2016: Epidemiology
Mohammad Ali Mansournia, Julian P T Higgins, Jonathan A C Sterne, Miguel A Hernán
Trialists and epidemiologists often employ different terminology to refer to biases in randomized trials and observational studies, even though many biases have a similar structure in both types of study. We use causal diagrams to represent the structure of biases, as described by the Cochrane Collaboration for randomized trials, and provide a translation to the usual epidemiologic terms of confounding, selection bias, and measurement bias. This structural approach clarifies that an explicit description of the inferential goal-the intention-to-treat effect or the per-protocol effect-is necessary to assess risk of bias in the estimates...
September 28, 2016: Epidemiology
James Milner, Paul Wilkinson
No abstract text is available yet for this article.
September 28, 2016: Epidemiology
Aurelio Tobías, Ben Armstrong, Antonio Gasparrini
BACKGROUND: The minimum mortality temperature from J- or U- shaped curves varies across cities with different climates. This variation conveys information on adaptation, but ability to characterize it is limited by the absence of a method to describe uncertainty in estimated minimum mortality temperatures. METHODS: We propose an approximate parametric bootstrap estimator of confidence interval (CI) and standard error (SE) for the minimum mortality temperature from a temperature-mortality shape estimated by splines...
September 28, 2016: Epidemiology
Catherine R Lesko, Bryan Lau
BACKGROUND: Epidemiologic studies that aim to estimate a causal effect of an exposure on a particular event of interest may be complicated by the existence of competing events that preclude the occurrence of the primary event. Recently, many articles have been published in the epidemiologic literature demonstrating the need for appropriate models to accommodate competing risks when they are present. However, there has been little attention to variable selection for confounder control in competing risk analyses...
September 28, 2016: Epidemiology
Yutaka Hamaoka
No abstract text is available yet for this article.
September 28, 2016: Epidemiology
Nicole Ah Janssen, Gerard Hoek, Paul H Fischer, Alet H Wijga, Gerard Koppelman, Johan J de Jongste, Bert Brunekreef, Ulrike Gehring
No abstract text is available yet for this article.
September 28, 2016: Epidemiology
Stephen Burgess, Jack Bowden, Tove Fall, Erik Ingelsson, Simon G Thompson
Mendelian randomization investigations are becoming more powerful and simpler to perform, due to the increasing size and coverage of genome-wide association studies and the increasing availability of summarized data on genetic associations with risk factors and disease outcomes. However, when using multiple genetic variants from different gene regions in a Mendelian randomization analysis, it is highly implausible that all the genetic variants satisfy the instrumental variable assumptions. This means that a simple instrumental variable analysis alone should not be relied on to give a causal conclusion...
September 26, 2016: Epidemiology
Sebastien Haneuse
No abstract text is available yet for this article.
September 26, 2016: Epidemiology
Sarah T Cherng, Jamie Tam, Paul J Christine, Rafael Meza
No abstract text is available yet for this article.
September 26, 2016: Epidemiology
Samir Soneji, Brian Primack, John Pierce, Hai-Yen Sung, James Sargent
No abstract text is available yet for this article.
September 26, 2016: Epidemiology
Mark Goldberg, Paul Villeneuve, Daniel Crouse
No abstract text is available yet for this article.
September 26, 2016: Epidemiology
Sonja A Swanson
No abstract text is available yet for this article.
September 20, 2016: Epidemiology
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