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“Mendelian randomization” refers to the random assortment of genes transferred from parent to offspring at the time of gamete formation. This process has been compared to a randomized controlled trial of genetic variants. This c...
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“Mendelian randomization” refers to the random assortment of genes transferred from parent to offspring at the time of gamete formation. This process has been compared to a randomized controlled trial of genetic variants. This could greatly aid observational epidemiology by potentially allowing an unbiased estimate of the effects of gene products on disease outcomes. However, studies utilizing Mendelian randomization to estimate effects of gene products on outcomes should be interpreted with caution. In this paper, the authors discuss some of the challenges facing epidemiologists in the analysis and interpretation of Mendelian randomization studies, particularly those that become apparent when the analogy with randomized controlled trials is closely examined. The authors conclude that Mendelian randomization is a powerful addition to etiologic research tools. However, care must be taken, because drawing valid causal inferences from its application depends upon more extensive assumptions than are required in randomized controlled trials.
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Risk ratio and risk difference are parameters of interest in many medical studies. The risk ratio has a property that the value for the outcome Y = 0 is not the inverse of the risk ratio for the outcome Y = 1. This property makes ...
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Risk ratio and risk difference are parameters of interest in many medical studies. The risk ratio has a property that the value for the outcome Y = 0 is not the inverse of the risk ratio for the outcome Y = 1. This property makes risk ratios inappropriate in some situations. Estimation of risk difference often encounters the problem that the binomial regression model fails to converge. Recently discussed alternatives may have the same problem of nonconvergence or are difficult to implement. Here the author proposes a modified least-squares regression approach— unweighted least-squares regression with a Huber-White robust standard error—for estimation of risk differences. Four versions of the robust standard error are considered. The binomial, ordinary least-squares, and modified least-squares estimators are compared analytically in a simple situation of one exposure variable. Multivariable regression analyses are simulated to demonstrate the usefulness of the approach. For sample sizes of approximately 200 or less, a small-sample version of the robust standard error is recommended. The method is illustrated with data from a patient survey in which the binomial regression fails to converge in the analyses of four out of five outcome variables.
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Objective: To quantify the effects of a thermostatic control system in social (public) housing on the prevalence of dangerous (>60°C) water temperatures and on fuel consumption. Design: Pair-matched double-blind cluster randomise...
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Objective: To quantify the effects of a thermostatic control system in social (public) housing on the prevalence of dangerous (>60°C) water temperatures and on fuel consumption. Design: Pair-matched double-blind cluster randomised controlled trial. Setting: Social housing in a deprived inner-London borough. Participants: 150 households recruited as clusters from 22 social housing estates. Four small estates were combined into two clusters (resulting in a total of 10 pairs of clusters). Intervention: Social housing estate boiler houses were randomised to a thermostatic control sterilisation programme (heating water to 65°C during 00:00-06:00 h and to 50°C from 06:00 to 00:00 h daily) or to standard control (constant temperature 65°C). Main outcome measures: Water temperature over 60°C ('dangerous') after running taps for 1 min and daily fuel consumption (cubic feet of gas). Results: 10 clusters (80 households) were allocated to the sterilisation programme and 10 clusters (70 households) to control, of which 73 and 67 households, respectively, were analysed. Prevalence of dangerous (>60°C) hot water temperatures at 1 min was significantly reduced with the sterilisation programme (mean of cluster prevalence 1% in sterilisation programme group vs 34% in control group; absolute difference 33%, 95% CI 12% to 54%; p=0.006). Prevalence of high (>55°C) hot water temperatures at 1 min was significantly reduced (31% sterilisation vs 59% control; absolute difference 28%, 95% CI 9% to 47%; p=0.009). Gas consumption per day reduced more in the control group than in the sterilisation programme group, although not statistically significantly (p=0.125). Conclusions: The thermostatic control with daily sterilisation was effective in capping hot water temperatures and therefore reduced scald risk. Although expected to save energy, fuel consumption was increased relative to the control group. Trial registration: ClinicalTrials.gov ID: NCT00874692.
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In the 18th century, Europe's main continuing environmental health hazards-as in many preceding centuries-were malnutrition and famine. After the 1740s this ancient health hazard began to recede in Europe as the modern agricultura...
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In the 18th century, Europe's main continuing environmental health hazards-as in many preceding centuries-were malnutrition and famine. After the 1740s this ancient health hazard began to recede in Europe as the modern agricultural revolution began. The extreme urban crowding and working-class poverty due to early industrialization in the 19th century resulted in infectious diseases becoming the dominant environmental health hazard. With the rise of modern large-scale industry and of synthetic organic chemistry in the 20th century, pollution of local environments-air, water, soil, and food-became the major focus of environmental health concerns in developed countries.
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Aims: To examine the evidence of association between intimate partner physical or sexual violence (IPV) victimization and alcohol consumption in women. Methods: We conducted a systematic review and meta-analysis of cross-sectional...
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Aims: To examine the evidence of association between intimate partner physical or sexual violence (IPV) victimization and alcohol consumption in women. Methods: We conducted a systematic review and meta-analysis of cross-sectional and longitudinal studies released before 6 June 2013. Studies providing an estimate of association between violence and alcohol consumption or alcohol use disorders were eligible for inclusion. Quality was assessed and random effects meta-analyses used to generate pooled odds ratios (OR) where appropriate. Higgins I2 where P<0.10 was taken to indicate heterogeneity. Results: Fifty-five studies providing 102 estimates of association met the inclusion criteria. Most estimates were not controlled for partner alcohol use and other key confounders. Seven longitudinal studies provided 12 estimates of the association between alcohol and subsequent IPV; nine of 12 estimates showed a direction of increased odds of subsequent IPV, pooled OR=1.27 [95% confidence interval (CI)=1.07-1.52], I2=0%, P=0.437. Nine longitudinal studies provided 15 estimates of association between IPV and subsequent alcohol use; 14 of 15 estimates showed a direction of increased odds of subsequent alcohol use, pooled OR=1.25 (95% CI 1.02-1.52), I2=0%, P=0.751. Cross-sectional studies showed an association between IPV and alcohol use, pooled OR=1.80, 95% CI 1.58-2.06, but with substantial heterogeneity, I2=60.8%, P<0.0001. Definition of alcohol use partly accounted for heterogeneity in cross-sectional estimates. Conclusions: There is a clear positive association between alcohol use and intimate partner physical or sexual violence victimization among women, suggesting a need for programming and research that addresses this link. However, the temporal direction of the association remains unclear. Longitudinal studies with multiple waves of data collection are needed.
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BCG uptake among infants in England has not been measured since targeted infant vaccination replaced universal schoolchildren vaccination in 2005, mainly because of the challenges in defining denominators. We estimated uptake betw...
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BCG uptake among infants in England has not been measured since targeted infant vaccination replaced universal schoolchildren vaccination in 2005, mainly because of the challenges in defining denominators. We estimated uptake between 2006 and 2008 by dividing number of BCG doses administered to infants by number of all live births (where BCG vaccination is universal) or ethnic minority/Eastern Europeans live births (where infant-BCG vaccination is selective). Weighted average uptake was 68% (95% CI 65% to 71%), slightly higher in primary care trusts with universal (72% (95% CI 64% to 80%)) than selective (66% (95% CI 61% to 70%)) policy; and also 13% higher in areas vaccinating in postnatal wards compared with community settings.
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Objectives To describe the sexual and reproductive behaviour of adolescents in sub-Saharan Africa, particularly 15- to 19-year-olds. Methods Using DHS/AIS data (2000-2010), nine indicators of adolescent behaviour and one of adult ...
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Objectives To describe the sexual and reproductive behaviour of adolescents in sub-Saharan Africa, particularly 15- to 19-year-olds. Methods Using DHS/AIS data (2000-2010), nine indicators of adolescent behaviour and one of adult attitudes towards condom education for adolescents were described for 24 countries. Indicators were disaggregated by gender, urban/rural residency and educational status, and time trends were described. Results Up to 25% of 15- to 19-year-olds reported sex before age 15; this proportion shrank over time in many countries. In most countries, ≥5% of females reported marriage before age 15, and >20% had commenced childbearing. Early sexual debut and childbearing were more common among the least educated and/or rural females. Reporting of multiple sexual partnerships was more common among males than among females, but decreases over time were more common among males. Urban males and females, and females with higher education, were more likely to report multiple partnerships. Urban youth and those with higher education also reported more condom use. Adult support for condom education for 12- to 14-year-olds has increased over time to 60-65%. Conclusions Many 15- to 19-year-olds are at risk of HIV/STIs and unplanned pregnancies because of multiple partnerships and insufficient condom and other contraceptive use. In many countries, trends are moving in a favourable direction. To better inform prevention programmes in this important area, we recommend routine collection of sexual and reproductive behaviour data for adolescents aged <15years, expanding the data collected for 15- to 19-year-olds to include detailed information on sexual behaviour within partnerships, and disaggregating data according to sociodemographic variables.
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Interactive text message-based technologies which operate in real time have the potential to be especially effective for delivery of relapse prevention interventions. We examined predictors of use of a text message system for prov...
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Interactive text message-based technologies which operate in real time have the potential to be especially effective for delivery of relapse prevention interventions. We examined predictors of use of a text message system for providing support for lapses and cravings, describe the natural history of requests for support, and predictors of time to requests for support. Data were collected prospectively from participants in the intervention arm of txt2stop, a large randomized controlled trial of an automated, text message-based smoking cessation intervention. Txt2stop included 2,915 men and women aged 16-78, recruited from London, United Kingdom from 2009 to 2010. Participants could text "crave" or "lapse" when they experienced either; an automated system registered the time of the text message to the nearest second. One thousand one hundred and twenty one (38.5%) participants sent a lapse or crave message to request support. Women were more likely to lapse at some point during the trial. Of those who lapsed, being female, younger age, and setting a Saturday quit date were predictors of sending a lapse text requesting support. Half of all crave texts arrived within 106 hr of quitting. Half of all lapse texts arrived between 4 and 17 days after the quit date. Sending a crave text, being female, younger, and setting a quit date on a Saturday were associated with shorter time to sending a first lapse text. Text-based lapse support should be developed and evaluated, especially for women. Smokers may benefit from additional support to prevent lapses on days 4-17 postquit attempt.
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Background: the evaluation of the determinants of change over time in health-related quality of life (HR-QoL) in older people is limited. This study aims to identify patterns of change in HR-QoL over 7 years and their determinants...
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Background: the evaluation of the determinants of change over time in health-related quality of life (HR-QoL) in older people is limited. This study aims to identify patterns of change in HR-QoL over 7 years and their determinants using data from the British Women's Heart and Health Study, a representative sample of older women (n = 4286).Methods: longitudinal latent class analysis was used to identify subpopulations of women with similar HR-QoL trajectories from 1999-2000 to 2007. HR-QoL was measured using the EQ-5D. Multivariate multinomial logistic regression was used to model the association of identified trajectories with baseline predictors after multiple imputation of missing data.Results: four distinct EQ-5D trajectories were suggested: high (19% of women), high decline (22%), intermediate (42%) and low decline (16%). Prevalent arthritis (OR = 13.4; 95% CI: 8.8, 20.5), diabetes (OR = 4.6; 95% CI: 1.5, 14.2) and obesity (OR = 3.9; 95% CI: 2.5, 6.0) were the strongest predicting health conditions of adverse changes in HR-QoL and physical activity the strongest predicting lifestyle factor (OR = 2.8; 95% CI: 2.0, 3.9).Conclusions: findings suggest that older women without obesity or pre-existing health conditions who undertake more physical activity are more likely to experience high HR-QoL, reinforcing the importance of these factors for healthy ageing.
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