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Background A recurring concern in traditional and in Web-based studies pertains to non-representativeness due to volunteer bias. We investigated this issue in an ongoing, large population-based e-cohort. Methods The sample included 122 912 individuals enrolled in the Internet-based, nutrition-focused NutriNet-Santé study between May 2009 and March 2014, with complete baseline data. Participants were recruited via recurrent multimedia campaigns and other traditional and online strategies. Individuals aged 18+ years, residing in France and having Internet access, were eligible for enrolment. Their sociodemographic characteristics were compared with the corresponding 2009 Census data via χ2 goodness-of-fit tests. The effectiveness of statistical weighting of the e-cohort data was also explored. Results The sample exhibited marked geographical and sociodemographic diversity, including volunteers belonging to typically under-represented subgroups in traditional surveys (unemployed, immigrants, the elderly). Nonetheless, the proportions of women, relatively welleducated individuals and those who are married or cohabiting, were notably larger compared with the corresponding national figures (women: 78.0% vs 52.4%; postsecondary education: 61.5% vs 24.9%; married or cohabiting: 70.8% vs 62.0%, respectively; all p<0.0001). Conclusions There were notable sociodemographic differences between the general French population and this general population-based e-cohort, some of which were corrected by statistical weighting. The findings bear on the potential generalisability of future investigations in the context of e-epidemiology. [ABSTRACT FROM AUTHOR]

Background We conducted a large registry-based study in California to investigate the association between race/ethnicity and childhood leukaemia focusing on two subtypes: acute lymphoblastic leukaemia (ALL) and acute myeloid leukaemia (AML). Methods We obtained information on 5788 cases and 5788 controls by linking California cancer and birth registries. We evaluated relative risk of childhood leukaemia by race and ethnicity of the child and their parents using conditional logistic regression, with adjustment for potential confounders. Results Compared with Whites, Black children had lower risk of ALL (OR=0.54, 95% CI 0.45 to 0.66) as well as children of Black/Asian parents (OR=0.31, 95% CI 0.10 to 0.94). Asian race was associated with increased risk of AML with OR=1.643, 95% CI 1.10 to 2.46 for Asian vs Whites; and OR=1.67, 95% CI 1.04 to 2.70 for Asian/Asian vs White/White. Hispanic ethnicity was associated with increased risk of ALL (OR=1.37, 95% CI 1.22 to 1.52). A gradient in risk of ALL was observed while comparing Hispanic children with both parents Hispanic, one parent Hispanic and non-Hispanic children (p Value for trend <0.0001). The highest risk of ALL was observed for children with a combination of Hispanic ethnicity and White race compared with non-Hispanic whites (OR=1.27, 95% CI 1.12 to 1.44). The lowest risk was observed for non-Hispanic blacks (OR=0.46, 95% CI 0.36 to 0.60). Associations for total childhood leukaemia were similar to ALL. Conclusions Our results confirm that there are ethnic and racial differences in the incidence of childhood leukaemia. These differences indicate that some genetic and/or environmental/cultural factors are involved in aetiology of childhood leukaemia. [ABSTRACT FROM AUTHOR]

Background Breast feeding duration has been associated with improved cognitive development in children. However, few population-based prospective studies have evaluated dose–response relationships of breastfeeding duration with language and motor development at early ages, and results are discrepant. Methods The study uses data from the prospective mother–child cohort (‘Rhea’ study) in Crete, Greece. 540 mother–child pairs were included in the present analysis. Information about parental and child characteristics and breastfeeding practices was obtained by interview-administered questionnaires. Trained psychologists assessed cognitive, language and motor development by using the Bayley Scales of Infant Toddler Development (3rd edition) at the age of 18 months. Results Duration of breast feeding was linearly positively associated with all the Bayley scales, except of gross motor. The association persisted after adjustment for potential confounders with an increase of 0.28 points in the scale of cognitive development (β=0.28; 95% CI 0.01 to 0.55), 0.29 points in the scale of receptive communication (β=0.29; 95% CI 0.04 to 0.54), 0.30 points in the scale of expressive communication (β=0.30; 95% CI 0.04 to 0.57) and 0.29 points in the scale of fine motor development (β=0.29; 95% CI 0.02 to 0.56) per accumulated month of breast feeding. Children who were breast fed longer than 6 months had a 4.44-point increase in the scale of fine motor development (β=4.44; 95% CI 0.06 to 8.82) compared with those never breast fed. Conclusions Longer duration of breast feeding was associated with increased scores in cognitive, language and motor development at 18 months of age, independently from a wide range of parental and infant characteristics. Additional longitudinal studies and trials are needed to confirm these results. [ABSTRACT FROM AUTHOR]

Background: In Rwanda, an estimated one million people were killed during the 1994 genocide, leaving the country shattered and social fabric destroyed. Large-scale traumatic events such as wars and genocides have been linked to endemic post-traumatic stress disorder, depression and suicidality. The study objective was to investigate whether the 1994 genocide exposure is associated with suicide in Rwanda. Methods: We conducted a population-based case--control study. Suicide victims were matched to three living controls for sex, age and residential location. Exposure was defined as being a genocide survivor, having suffered physical/sexual abuse in the genocide, losing a first-degree relative in the genocide, having been convicted for genocide crimes or having a first-degree relative convicted for genocide. From May 2011 to May 2013, 162 cases and 486 controls were enrolled countrywide. Information was collected from the police, local village administrators and family members. Results: After adjusting for potential confounders, having been convicted for genocide crimes was a significant predictor for suicide (OR=17.3, 95% CI 3.4 to 88.1). Being a survivor, having been physically or sexually abused during the genocide, and having lost a first-degree family member to genocide were not significantly associated with suicide. Conclusions: These findings demonstrate that individuals convicted for genocide crimes are experiencing continued psychological disturbances that affect their social reintegration into the community even 20 years after the event. Given the large number of genocide perpetrators reintegrated after criminal courts and Gacaca traditional reconciling trials, suicide could become a serious public health burden if preventive remedial action is not identified. [ABSTRACT FROM AUTHOR]

Background Mortality increases during heat waves have been reported worldwide. The magnitude of these increases can vary within regions according to sociodemographic and urban landscape characteristics. The objectives of this study were to explore this variation and its determinants, and to identify the most heat-vulnerable areas by mapping heat vulnerability. Methods We conducted a time-stratified case-crossover analysis using daily mortality in the Barcelona metropolitan area during the warm seasons of 1999-2006. Temperature data on the date of death were assigned to each individual, which were assigned to their census tract of residence. Eight census tract-level variables on socioeconomic or built environment characteristics were obtained from the census. Residence surrounding greenness was obtained from satellite data. The relative risk (RR) of mortality after three consecutive hot days (defined as those exceeding the 95th percentile of maximum temperature) was calculated via conditional logistic regression. Effect modification was examined by including interaction terms. Results Analyses were based on 52 806 deaths. The effect of three consecutive hot days was a 30% increase in all-cause mortality (RR=1.30, 95% CI 1.24 to 1.38). Heterogeneity of this effect was observed across census tracts. The effect of heat on mortality was higher in the census tracts with a large percentage of old buildings (RR=1.21, 95% CI 1.00 to 1.46), manual workers (RR=1.25, 95% CI 0.96 to 1.64) and residents perceiving little surrounding greenness (RR=1.29, 95% CI 1.01 to 1.65). After three consecutive hot days, mortality doubled in the most heat-vulnerable census tracts. Conclusions Sociodemographic and urban landscape characteristics are associated to mortality risk during heat waves and are useful to build heat vulnerability maps. [ABSTRACT FROM AUTHOR]

Background and objective While risk factors for suicide have been established, the impact of social context in moderating the impact of these factors is poorly understood. Methods Data from case-control studies published between 1950 and 2006 that examined socio-demographic risk factors for suicide in clinical, occupational and general populations were extracted. Odds ratios for risk factors for suicide (employment, ethnicity, living circumstances and marital status) were correlated with the prevalence of these risk factors among controls. Results Data were extracted from 54 studies. Negative correlations were demonstrated for the odds ratio and prevalence of unemployment (ρ=∧0.73), living alone (ρ=∧0.46) and being from an ethnic minority community (ρ=∧0.68). Conclusion The impact of some socio-demographic risk factors for suicide appears to be accentuated when they are less prevalent in the population from which cases are derived. When assessing an individual's risk of suicide, consideration should be given to the prevalence of risk factors in the area where the individual lives. [ABSTRACT FROM AUTHOR]

Background This study aimed to examine prospective associations of young infants' home environments with expressive vocabulary delay and internalising and externalising problem scores independently of family socioeconomic status (SES) and national origin. Methods Prospective data from fetal life to age 3 were collected in a total of 2711 families participating in the Generation R Study, a longitudinal population-based cohort. Infants' home environments (ie, the learning environment and the physical environment) were assessed exclusively by observation in their first few months of life (mean age=3.38 months, SD=1.17). Internalising and externalising problems were measured at age 1.5 and 3; expressive vocabulary delay was assessed at age 2.5. Family socio-demographic characteristics, including SES variables and national origin, were measured during pregnancy. Results Lower quality learning environments of young infants, but not physical environments, were associated with expressive vocabulary delay and more internalising problems in toddlerhood independently of SES and national origin. Associations of SES and national origin with children's outcomes were reduced when the home environmental variables were added to the regression model. Conclusions The current findings suggest that SES and national origin are reflected, to some degree, in the quality of infants' home environments. Some of the possible interpretations of these results are discussed together with their implications for the early identification of children at risk of impaired development. [ABSTRACT FROM AUTHOR]

Background There is a strong case for early identification of factors predicting life-course-persistent conduct disorder. The authors aimed to identify factors associated with repeated parental reports of preschool conduct problems. Method Nested case-control study of Scottish children who had behavioural data reported by parents at 3, 4 and 5 years. Results 79 children had abnormal conduct scores at all three time points ('persistent conduct problems') and 434 at one or two points ('inconsistent conduct problems'). 1557 children never had abnormal scores. Compared with children with no conduct problems, children with reported problems were significantly more likely to have mothers who smoked during pregnancy. They were less likely to be living with both parents and more likely to be in poor general health, to have difficulty being understood, to have a parent who agrees that smacking is sometimes necessary and to be taken to visit other people with children rarely. The results for children with persistent and inconsistent conduct problems were similar, but associations with poverty and maternal smoking were significantly less strong in the inconsistent group. Conclusion These factors may be valuable in early identification of risk of major social difficulties. [ABSTRACT FROM AUTHOR]

Background The source of infection for most sporadic cases of Legionnaires' disease remains unknown. This study aims quantify the relationship between cases and wet cooling systems (WCS), a potential source of aerosolised legionella bacteria. Methods The study analysed data on 1163 sporadic, community-acquired cases of Legionnaires' disease in England and Wales with onset between 1996 and 2006, and 11630 postcode controls randomly sampled in proportion to population size and matched on region, age group and sex. The relationship between risk of Legionnaires' disease and distance from a WCS was analysed by conditional logistic regression. Results Cases and controls had a mean age of 56.3 years; 79.3% were male. Cases lived appreciably closer to WCS than their controls (mean distance of cases=2.11 km, controls=2.58 km; mean difference 0.47 km (95% CI 0.28 to 0.65)). The OR for disease within 1 km of a WCS compared with over 6 km (a distance taken to reflect background rates of Legionnaires' disease) was 1.59 (95% CI 1.26 to 2.01) when adjusted for socio-economic deprivation, and 1.33 (95% CI 1.04 to 1.71) when additionally adjusted for population density. The results suggest that residential proximity to a WCS may account for 19.6% of sporadic community-acquired cases. Conclusions WCS may be an important source of sporadic, community-acquired cases of Legionnaires' disease, an observation that has important implications for health protection, especially given the likely increase in such systems as a component of strategies to improve energy efficiency in buildings. [ABSTRACT FROM AUTHOR]

Background A range of studies have found an association between some somatic diseases and increased risk of suicide and attempted suicide. These studies are mostly analyses of adult populations and illnesses related to adulthood. Objectives To study the risk of attempted suicide in children and youths with a somatic diagnosis, and to assess a possible association from a somatic perspective. Methods From a cohort of 403 431 individuals (born 1983-89), 3465 children and youths who had attempted suicide were identified. Each case was matched with 20 population controls. 72 765 children and youths constituted the case-control population. All data were obtained from national population registers and analysed in a nested case-control design. Results Contact of children and youths with a somatic hospital is correlated with increased risk of attempted suicide; the risk peaks in the time immediately after contact. Risk factors were treatment for injury caused by violence, epilepsy, asthma and malformation for males; and spontaneous and medical abortions, treatment for injury caused by violence, epilepsy, asthma, insulin dependent diabetes mellitus and malformation for females. Not all the mentioned diagnoses were significant in the adjusted model. Conclusions Based on the results of the study a strategy to minimise the risk of attempted suicide among children and youths must be implemented. The strategy should mainly focus on children at high risk--that is, children from families with low socioeconomic status, and children with a psychiatric history, a history of previous suicide attempts and with an unstable somatic disease subsequently causing many admissions. [ABSTRACT FROM AUTHOR]

Background A higher burden of head and neck cancer has been reported to affect deprived populations. This study assessed the association between socioeconomic status and head and neck cancer, aiming to explore how this association is related to differences of tobacco and alcohol consumption across socioeconomic strata. Methods We conducted a case-control study in São Paulo, Brazil (1998-2006), including 1017 incident cases of oral, pharyngeal and laryngeal cancer, and 951 sex- and age-matched controls. Education and occupation were distal determinants in the hierarchical approach; cumulative exposure to tobacco and alcohol were proximal risk factors. Outcomes of the hierarchical model were compared with fully adjusted ORs. Results Individuals with lower education (OR 2.27; 95% CI 1.61 to 3.19) and those performing manual labour (OR 1.55; 95% CI 1.26 to 1.92) had a higher risk of disease. However, 54% of the association with lower education and 45% of the association with manual labour were explained by proximal lifestyle exposures, and socioeconomic status remained significantly associated with disease when adjusted for smoking and alcohol consumption. Conclusions Socioeconomic differences in head and neck cancer are partially attributable to the distribution of tobacco smoking and alcohol consumption across socioeconomic strata. Additional mediating factors may explain the remaining variation of socioeconomic status on head and neck cancer. [ABSTRACT FROM AUTHOR]

Background This study investigated the impact of the Healthy Housing Programme in reducing acute hospitalisations in South Auckland, New Zealand. The programme involved house modifications to reduce overcrowding, insulation and ventilation improvements, and health and social service assessments, referrals and linkages. Methods An intervention evaluation was used. Participants in the programme were considered cases following their house's intervention and counterfactuals/ controls prior to the intervention. Rigorous age-censoring was used to construct a case-counterfactual comparison. 9736 residents of 3410 homes were involved in the programme from September 2001 to December 2007. All lived in areas of relative deprivation (NZDep01=decile 10) and almost all self-identified as Pacific ethnic group. The main outcome measure was acute hospitalisation rates before, during and after a health and housing intervention. Hospital data were gathered from July 1999 to January 2009. Results In the post-intervention group, people aged 5-34 years had a HR of 0.77 (95% CI 0.70 to 0.85) for acute hospitalisations compared to the counterfactual (pre-intervention). For children aged 0-4 years the HR was 0.89 (95% CI 0.79 to 0.99); a non-significant increase occurred in adults aged 35 years plus. When the causes of hospitalisation were restricted to those related to housing, further falls in the HRs were seen: 0.88 (95% CI 0.74 to 1.05) for 0e4 year olds and 0.73 (95% CI 0.58 to 0.91) for 5-34 year olds. Conclusion A package of care that addresses housing conditions that impact on health and improves access to health and social services is associated with a reduced acute hospitalisation rate for 0-34 year olds. [ABSTRACT FROM AUTHOR]

Objectives To determine whether children who have child maltreatment allegation or substantiation have a higher rate of general hospital admissions and injury related admissions when compared to other children and to investigate other types of admissions, such as mental health, infections and admissions due to external causes. Study design A prospective matched case-control study of children born in Western Australia between 1990 and 2005 using de-identified record linked Child Protection and Hospital Morbidity data. Rates of prior hospital admissions for cases versus controls were calculated, and conditional logistic regression was used to estimate the effect of hospital admission rate on the risk of child maltreatment allegation and substantiated allegation. Results Children with child maltreatment allegations and substantiations had higher mean prior admission rates compared to controls. Higher rates of general admissions and admissions for injuries, infections, mental and behavioural disorders, and external causes of morbidity, were associated with a markedly increased risk of child maltreatment allegations and substantiation. Conclusions The hospital system plays not only an important role both in the surveillance of maltreatment-related injuries and conditions but also in the role of prevention in the referral of families who may need support and assistance in ensuring the health and safety of their children. This research highlights the importance of moving to electronic patient records in identifying children who have high rates of admissions and the types of conditions they have previously presented with, particularly for injuries, mental and behavioural disorders and external causes of admissions. [ABSTRACT FROM AUTHOR]