Author: ijeeditorial

The relevance of a local cohort: the case for generalisability over representativeness

Eleonora Uphoff, Neil Small, Rosie McEachan and Kate Pickett

For some years, our research has been based in the city of Bradford in northern England. We are often asked to justify our research setting. There seems to be a concern that a cohort population that is not representative of the nation as a whole or of the ‘average person’ cannot produce valuable insights beyond its local setting.

While such concerns are not new, they now seem more present, perhaps due to the rise of Big Data or the increased sharing of and access to data from national surveys and cohorts. Do these reservations represent a push for representativeness and generalisability in epidemiology? If so, this might come at the expense of research aiming to paint a more detailed picture of population health.

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Could pre-gestational weight status affect children’s cognition?

Vicente Martínez-Vizcaíno, Celia Álvarez-Bueno and Iván Cavero-Redondo

Our study, recently published in the IJE, looks at the relationship between pre-gestational weight status and children’s neurodevelopment. It shows that children born to mothers who were normal weight before pregnancy scored better on cognition tests than children born to obese women. An original aspect of our study is that it summarises the evidence provided by 15 previous follow-up studies, including samples from seven different countries, and provides information for both cognition tests and general intelligence scores.

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It only takes a minute, girl: women who run for just 1 minute per day have better bone health

Vicky Stiles, Brad Metcalf, Karen Knapp and Alex Rowlands

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We don’t yet know whether it’s best to do it all at once, or little and often, but what we do know is that if a woman’s day-to-day activity contains 1–2 minutes of weight-bearing, high-intensity activity, similar to a medium-paced run for pre-menopausal women or a slow jog for post-menopausal women, she will have better bone health than women who do less. The benefits of high-impact activity on bone health are nothing new. What is novel about our findings is that better bone health is linked to such a short amount of daily activity, albeit at an intensity of the running variety.

Continue reading “It only takes a minute, girl: women who run for just 1 minute per day have better bone health” →

Varenicline produces enduring smoking cessation when prescribed in primary care regardless of patients’ socioeconomic position

Gemma MJ Taylor, Amy E Taylor, Kyla H Thomas, Tim Jones, Richard M Martin, Marcus R Munafò and Neil M Davies

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Tobacco is the world’s leading cause of premature disease and death. One in two smokers will die from their addiction unless they quit. Smoking is also a major contributor to health inequalities between the richest and poorest in society. Evidence from the Health Improvement Network in the United Kingdom indicates that smokers from more deprived groups are just as likely as those from less deprived groups to receive advice to quit from their GP. However, evidence from observational studies suggests that smokers from disadvantaged backgrounds are much less likely to quit, even after accessing treatment from specialist stop-smoking services.

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Adolescent cannabis use and educational attainment: a causal relationship?

Maria Melchior, Laura Pryor and Marie Jauffret-Roustide

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Our study, recently published in the IJE, shows that youths who initiate cannabis use before the age of 17 years are 60% less likely to pursue higher education than those who never used cannabis. An original aspect of our study, which was based on data from the longitudinal TEMPO cohort in France, is that we were able to take into account youths’ psychological and school difficulties in childhood and adolescence, as well as their parents’ characteristics.

In recent decades, cannabis use has become frequent among youths growing up in Europe, North America and Australasia. The potential health effects of cannabis use include reductions in memory and concentration. Because the brain is thought to develop until the age of 25, adolescent substance use could have lasting negative effects on executive functions, which can in turn result in school difficulties and low educational achievement.

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Spatial quantification of the world population potentially exposed to Zika virus: how many people are in danger?

Alberto J. Alaniz, Antonella Bacigalupo and Pedro E. Cattan

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Our study, published recently in the IJE, shows that 43.9% of the world population — about three billion people — are exposed to Zika virus, due to the probability of presence of its vector: the mosquito Aedes aegypti.

Zika virus has become an important public health problem worldwide. In 2016, the World Health Organization released a global alert in response to the risk of this virus to the population. The pathogen is especially aggressive in pregnant women, because it has been associated with microcephaly in the fetus. On the other hand, it causes different clinical manifestations in adults, such as mild fever, rash, headache and joint pain. In some countries the alert was very restrictive, even going so far as to contemplate birth control programs to avoid the infection of pregnant women.

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Causality in Epidemiology – Themed issue

jane-ferrieJane E Ferrie

Arguments about causal inference in ‘modern epidemiology’ revolve around the ways in which causes can and should be defined. The potential outcomes approach, a formalized kind of counterfactual reasoning, often aided by directed acyclic graphs (DAGs), can be seen as too rigid and too far removed from many of the complex ‘dirty’ problems of social epidemiology, such as social inequalities and racism. If a potential ‘cause’ cannot be manipulated is it sensible to disregard it, relegating it to the ‘not suitable for epidemiology’ category? The use of properly constructed DAGs may aid causal thinking and help plan relevant analyses – Neil Pearce and Debbie Lawlor provide a simple, but excellent discussion of the use of DAGs in their essay review of Causal Inference in Statistics: A Primer by Judea Pearl and colleagues. However, increasingly, DAGs and analyses are constructed by computer programs, such as DAGitty, now available as an R package ‘dagitty’. Useful as such programmes are, the temptation to use evaluations of DAG-dataset inconsistency to generate purely data-driven, post-hoc modifications to DAGs, raises concern about overfitting and biased inference. Continue reading “Causality in Epidemiology – Themed issue” →

Exposure to physical assault is associated with premature mortality in Russian men

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Vishal Bhavsar

Our study, published recently in the IJE, looks at the relationship between experience of violence, in the form of physical assault in the previous 12 months, and premature mortality in a sample of working-age Russian men living in Izhevsk in the Southern Urals.

We did this study because, although violence is considered important at a policy and political level, empirical public health research on the subject is patchy. There has been quite a lot of research on the relationship between violence exposure and later mental health problems, particularly post-traumatic stress disorder, and more generally the impact of violence on coping and psychological characteristics, particularly in children. Recently, there has been considerable work on the descriptive epidemiology of violence against women, both from a general population perspective and in studies focusing on women with serious mental illness.

In contrast, we found that population-based research on the physical health effects of exposure to violence was limited, and we decided to focus on possible associations between assault and mortality in our study.

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Metabolic Phenotyping in Epidemiology

g-mak-talisker-jan-2016-bristol-wwwMika Ala-Korpela and George Davey Smith

Metabolic phenotyping, nowadays most often termed metabolomics, is becoming increasingly applied in epidemiology. Recent technological developments, driven by mass spectrometry and nuclear magnetic resonance spectroscopy, have recently resulted in increasing numbers of quantitative molecular applications at an epidemiological scale. The results suggest that these kinds of new technologies are inevitably becoming common in research projects aiming for molecular understanding of metabolic health and diseases. It is also evident from the epidemiological applications that absolute quantification of identified molecular entities is the very key for biomedical applications, not to mention potential clinical translation of metabolomics methodologies and findings. Continue reading “Metabolic Phenotyping in Epidemiology” →

Evolution or revolution? The health of New Yorkers under Mayor Bloomberg

Peter Muenning, Daniel Vail and Ryan K. Masters

hss_cohort9-ryan-mastersdaniel121757476_title0hWhen Michael Bloomberg was elected Mayor of New York City (NYC), he set forth an ambitious agenda to efficiently sync municipal agencies. Improving New Yorkers’ health was part of his motivation. For example, expanding parks and bike lanes would not only improve people’s quality of life and expand transportation options, their presence would also encourage healthy behaviours. So, why not create cross-agency agendas that allow parks with bike lanes to be created on city streets? Innovative thinkers were hired and were given an unusual amount of political capital and logistical support to implement their plans.

Sadly, very little was done to actually evaluate the programs that were implemented. When the Bloomberg administration promoted the idea that life expectancy had greatly increased as a result of its coordinated policymaking, some people scratched their heads. Sam Preston and Irma Elo argued that improvements in life expectancy in NYC could be explained by a large inflow of healthy foreign migrants. They made this argument by eloquently showing the influence that immigrants had on the city’s life expectancy.
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