Socioeconomic position, family context, and child cognitive development.

Socioeconomic position (SEP) may have different effects on cognitive development and family context could play a role in this association. This work aimed to analyse the role of socioeconomic positions, measured via various indicators collected longitudinally, in cognitive development at 7-11 years of age, evaluating the role of family context as a potential mediator. The study sample included 394 and 382 children from the INMA Gipuzkoa and Valencia cohorts, respectively. SEP indicators were assessed during pregnancy (family social class, parental education, employment, and disposable income) and at 7 (Gipuzkoa) and 11 (Valencia) years of age (At Risk of Poverty or Social Exclusion (AROPE)). Family context and cognitive development were measured with the Haezi-Etxadi Family Assessment Scale 7-11 (HEFAS 7-11) and Raven's Coloured Progressive Matrices (Raven's CPM), respectively. Linear regression models were developed to assess the relationships between (a) SEP-family context, (b) SEP-cognitive development, and (c) family context-cognitive development, adjusting for a priori-selected confounders. Simple and multiple mediation analyses were performed to explore the role of family context in the SEP-cognitive development relationship. Lower SEP was related with a lower cognitive score, this association being particularly robust for family social class. SEP indicators were related to subscales of family context, in particular those regarding cognitive stimulation, parental stress, and parenting. A relationship was also found between these three subscales and child cognitive development, mediating the effect of family social class on child cognition by 5.2, 5.5, and 10.8%, respectively, and 12.0% jointly.    Conclusion: Both family SEP and context contribute to a child's cognitive development. Equalising policies and positive parenting programmes could contribute to improving cognitive development in children. What is Known: • Parental social class, education, and employment status have been widely employed to measure socioeconomic position. What is New: • This work focuses on standard measurements of socioeconomic position but also other economic indicators such as the EHII and AROPE, and their effect on child cognitive development and family context. • Promotion of cognitive and linguistic development, parental stress and conflict, and parental profile fostering child development mediated the effect of family social class on cognitive development.

Modelling socioeconomic position as a driver of the exposome in the first 18 months of life of the NINFEA birth cohort children.

BACKGROUND: The exposome drivers are less studied than its consequences but may be crucial in identifying population subgroups with unfavourable exposures. OBJECTIVES: We used three approaches to study the socioeconomic position (SEP) as a driver of the early-life exposome in Turin children of the NINFEA cohort (Italy). METHODS: Forty-two environmental exposures, collected at 18 months of age (N = 1989), were classified in 5 groups (lifestyle, diet, meteoclimatic, traffic-related, built environment). We performed cluster analysis to identify subjects sharing similar exposures, and intra-exposome-group Principal Component Analysis (PCA) to reduce the dimensionality. SEP at childbirth was measured through the Equivalised Household Income Indicator. SEP-exposome association was evaluated using: 1) an Exposome Wide Association Study (ExWAS), a one-exposure (SEP) one-outcome (exposome) approach; 2) multinomial regression of cluster membership on SEP; 3) regressions of each intra-exposome-group PC on SEP. RESULTS: In the ExWAS, medium/low SEP children were more exposed to greenness, pet ownership, passive smoking, TV screen and sugar; less exposed to NO2, NOX, PM25abs, humidity, built environment, traffic load, unhealthy food facilities, fruit, vegetables, eggs, grain products, and childcare than high SEP children. Medium/low SEP children were more likely to belong to a cluster with poor diet, less air pollution, and to live in the suburbs than high SEP children. Medium/low SEP children were more exposed to lifestyle PC1 (unhealthy lifestyle) and diet PC2 (unhealthy diet), and less exposed to PC1s of the built environment (urbanization factors), diet (mixed diet), and traffic (air pollution) than high SEP children. CONCLUSIONS: The three approaches provided consistent and complementary results, suggesting that children with lower SEP are less exposed to urbanization factors and more exposed to unhealthy lifestyles and diet. The simplest method, the ExWAS, conveys most of the information and is more replicable in other populations. Clustering and PCA may facilitate results interpretation and communication.

Determination of saliva epigenetic age in infancy, and its association with parental socio-economic characteristics and pregnancy outcomes.

Epigenetic age acceleration (AA) has been associated with adverse environmental exposures and many chronic conditions. We estimated, in the NINFEA birth cohort, infant saliva epigenetic age, and investigated whether parental socio-economic position (SEP) and pregnancy outcomes are associated with infant epigenetic AA. A total of 139 saliva samples collected at on average 10.8 (range 7-17) months were used to estimate Horvath's DNA methylation age. Epigenetic AA was defined as the residual from a linear regression of epigenetic age on chronological age. Linear regression models were used to test the associations of parental SEP and pregnancy outcomes with saliva epigenetic AA. A moderate positive association was found between DNA methylation age and chronological age, with the median absolute difference of 6.8 months (standard deviation [SD] 3.9). The evidence of the association between the indicators of low SEP and epigenetic AA was weak; infants born to unemployed mothers or with low education had on average 1 month higher epigenetic age than infants of mothers with high education and employment (coefficient 0.78 months, 95% confidence intervals [CIs]: -0.79 to 2.34 for low/medium education; 0.96, 95% CI: -1.81 to 3.73 for unemployment). There was no evidence for association of gestational age, birthweight or caesarean section with infant epigenetic AA. Using the Horvath's method, DNA methylation age can be fairly accurately predicted from saliva samples already in the first months of life. This study did not reveal clear associations between either pregnancy outcomes or parental socio-economic characteristics and infant saliva epigenetic AA.

Measuring Child Socio-Economic Position in Birth Cohort Research: The Development of a Novel Standardized Household Income Indicator.

The assessment of early life socioeconomic position (SEP) is essential to the tackling of social inequalities in health. Although different indicators capture different SEP dimensions, maternal education is often used as the only indicator in birth cohort research, especially in multi-cohort analyses. Household income, as a direct measure of material resources, is one of the most important indicators, but one that is underused because it is difficult to measure through questionnaires. We propose a method to construct a standardized, cross-cohort comparable income indicator, the "Equivalized Household Income Indicator (EHII)", which measures the equivalized disposable household income, using external data from the pan-European Union Statistics on Income and Living Conditions (EUSILC) surveys, and data from the cohorts. We apply this method to four studies, Piccolipiù and NINFEA from Italy and ELFE and EDEN from France, comparing the distribution of EHII with other SEP-related variables available in the cohorts, and estimating the association between EHII and child body mass index (BMI). We found that basic parental and household characteristics may be used, with a fairly good performance, to predict the household income. We observed a strong correlation between EHII and both the self-reported income, whenever available, and other individual socioeconomic-related variables, and an inverse association with child BMI. EHII could contribute to improving research on social inequalities in health, in particular in the context of European birth cohort collaborative studies.

Socioeconomic inequalities in reproductive outcomes in the Italian NINFEA birth cohort and the Piedmont Birth Registry.

BACKGROUND: socioeconomic inequalities in reproductive outcomes have been consistently reported in several countries. In a European collaborative study conducted in 2012 whose aim was to investigate the association between socioeconomic position (SEP), measured through maternal education, and preterm delivery inconsistent results were found for the NINFEA birth cohort. However, NINFEA contributed to that study with the first 2,500 pregnancies only, and estimates were not adjusted for any potential confounders assuming that SEP is a distal exposure, that could not be affected by other preterm risk factors. OBJECTIVES: to investigate the relationship between SEP and the reproductive outcomes using the entire NINFEA cohort and compare the results with the population-based Piedmont Birth Registry (PBR), accounting for potential baseline collider bias both in the cohort and in the registry. DESIGN: observational study. SETTING AND PARTICPANTS: 5,323 NINFEA singletons, whose mothers registered into the study before the 36th week of gestation, were analysed. Analyses on maternal education were replicated in the 2011 PBR of 35,318 singletons live births. Factors affecting the likelihood of being a member of the NINFEA study or becoming pregnant in the general population were treated as potential confounders to adjust for baseline collider bias. MAIN OUTCOME MEASURES: the association of maternal education and a recently developed household income indicator with both preterm delivery (<37th weeks of gestation) and low birth weight (<2,500 gr) were analysed. RESULTS: in the NINFEA cohort, low SEP was positively associated with both preterm delivery and low birth weight, with slightly stronger associations for household income, especially on low birth weight. Results were consistent with those obtained in the PBR data, where an inverse relationship between maternal education and the two reproductive outcomes was found. In both populations, there was confounding due to maternal age and parity, showing that independently of the nature of the source population, baseline factors that affect the probability of being a member of such source population have to be accounted for to allow causal inference. CONCLUSIONS: low SEP is associated with adverse reproductive outcomes in a contemporary Italian population.

[The NINFEA project and the emerging forms of engagement of citizens in epidemiological research]. / Il progetto NINFEA e le nuove forme di coinvolgimento dei cittadini nella ricerca epidemiologica.

In the last decade a new form of participation of the citizens in research activities and in the production of knowledge has emerged.This development has started to reach epidemiological research, as illustrated in the recent section "EpiChange" of the journal Epidemiologia e Prevenzione. The conduction of epidemiological research through the engagement of citizens and new forms of production of knowledge - including peer-production - is still in its infancy. In 2005,we started in Italy a birth cohort, the NINFEA project, which uses the Internet to recruit pregnant women and to follow-up their children. Participants are volunteers who decide to take part in the research project. In this paper, we consider the aspects of the NINFEA project that are consistent with the concept of collaborative production of knowledge. In particular,we discuss issues related to the motivation of the participants, the selection of the research hypotheses to be evaluated and the definition of the population of interest of the study.

Exploring educational disparities in risk of preterm delivery: a comparative study of 12 European birth cohorts.

BACKGROUND: An association between education and preterm delivery has been observed in populations across Europe, but differences in methodology limit comparability. We performed a direct cross-cohort comparison of educational disparities in preterm delivery based on individual-level birth cohort data. METHODS: The study included data from 12 European cohorts from Denmark, England, France, Lithuania, the Netherlands, Norway, Italy, Portugal, and Spain. The cohorts included between 2434 and 99 655 pregnancies. The association between maternal education and preterm delivery (22-36 completed weeks of gestation) was reported as risk ratios, risk differences, and slope indexes of inequality with 95% confidence intervals (CIs). RESULTS: Singleton preterm live delivery proportion varied between 3.7% and 7.5%. There were large variations between the cohorts in the distribution of education and maternal characteristics. Nevertheless, there were similar educational differences in risk of preterm delivery in 8 of the 12 cohorts with slope index of inequality varying between 2.2 [95% CI 1.1, 3.3] and 4.0 [95% CI 1.4, 6.6] excess preterm deliveries per 100 singleton deliveries among the educationally most disadvantaged, and risk ratio between the lowest and highest education category varying from 1.4 [95% CI 1.1, 1.8] to 1.9 [95% CI 1.2, 3.1]. No associations were found in the last four cohorts. CONCLUSIONS: Educational disparities in preterm delivery were found all over Europe. Despite differences in the distributions of education and preterm delivery, the results were remarkably similar across the cohorts. For those few cohorts that did not follow the pattern, study and country characteristics did not explain the differences.

Piccolipiù, a multicenter birth cohort in Italy: protocol of the study.

BACKGROUND: The fetal and infant life are periods of rapid development, characterized by high susceptibility to exposures. Birth cohorts provide unique opportunities to study early-life exposures in association with child development and health, as well as, with longer follow-up, the early life origin of adult diseases. Piccolipiù is an Italian birth cohort recently set up to investigate the effects of environmental exposures, parental conditions and social factors acting during pre-natal and early post-natal life on infant and child health and development. We describe here its main characteristics. METHODS/DESIGN: Piccolipiù is a prospective cohort of expected 3000 newborns, who will be recruiting in six maternity units of five Italian cities (Florence, Rome, Trieste, Turin and Viareggio) since October 2011. Mothers are contacted during pregnancy or at delivery and are offered to participate in the study. Upon acceptance, their newborns are recruited at birth and followed up until at least 18 years of age. At recruitment, the mothers donate a blood sample and complete a baseline questionnaire. Umbilical cord blood, pieces of umbilical cord and heel blood spots are also collected. Postnatal follow-up currently occurs at 6, 12, and 24 months of age using on-line or postal self administered questionnaire; further questionnaires and medical examinations are envisaged. Questionnaires collect information on several factors, including mother's and/or child's environmental exposures, anthropometric measures, reproductive factors, diet, supplements, medical history, cognitive development, mental health and socioeconomic factors. Health promotion materials are also offered to parents. DISCUSSION: Piccolipiù will broaden our understanding of the contribution of early-life factors to infant and child health and development. Several hypotheses on the developmental origins of health can be tested or piloted using the data collected from the Piccolipiù cohort. By pooling these data with those collected by other existing birth cohorts it will be possible to validate previous findings and to study rare exposures and outcomes.

Which factors account for the ethnic inequalities in stage at diagnosis and cervical cancer survival in New Zealand?

OBJECTIVE: There are substantial ethnic inequalities in stage at diagnosis and cervical cancer survival in New Zealand. We assessed what proportions of these differences were due to screening history (for the analyses of late stage diagnosis), stage at diagnosis (for the analyses of survival), comorbid conditions (for the analyses of survival), and travel time to the nearest General Practitioner and cancer centre. METHODS: The study involved 1594 cervical cancer cases registered during 1994-2005. We used G-computation to assess the validity of the estimates obtained by standard logistic regression methods. RESULTS: Maori women had a higher risk of late stage diagnosis compared with 'Other' (mainly European) women (odds ratio (OR) = 2.71; 95% confidence interval 1.98, 3.72); this decreased only slightly (OR 2.39; 1.72, 3.30) after adjustment for screening history, and travel time to the nearest General Practitioner and cancer centre. In contrast, the (non-significantly) elevated risk in Pacific women (1.39; 0.76, 2.54) disappeared almost completely when adjusted for the same factors (1.06; 0.57, 1.96). The hazard ratio of mortality for cervical cancer for Maori women was 2.10 (1.61, 2.73) and decreased to 1.45 (1.10, 1.92) after adjustment for stage at diagnosis, comorbid conditions, and travel time to the nearest General Practitioner and cancer centre; the corresponding estimates for Pacific women were 1.96 (1.23, 3.13) and 1.55 (0.93, 2.57). The G-computation analyses gave similar findings. CONCLUSIONS: The excess relative risk of late stage diagnosis in Maori women remains largely unexplained, while more than half of the excess relative risk of mortality in Maori and Pacific women is explained by differences in stage at diagnosis and comorbid conditions.

Effects of Italian smoking regulation on rates of hospital admission for acute coronary events: a country-wide study.

BACKGROUND: Several studies have reported a reduction in acute coronary events (ACEs) in the general population after the enforcement of smoking regulations, although there is uncertainty concerning the magnitude of the effect of such interventions. We conducted a country-wide evaluation of the health effects of the introduction of a smoking ban in public places, using data on hospital admissions for ACEs from the Italian population after the implementation of a national smoking regulation in January 2005. METHODS AND FINDINGS: Rates of admission for ACEs in the 20 Italian regions from January 2002 to November 2006 were analysed using mixed-effect regression models that allowed for long-term trends and seasonality. Standard methods for interrupted time-series were adopted to assess the immediate and gradual effects of the smoking ban. Effect modification by age was investigated, with the assumption that exposure to passive smoking in public places would be greater among young people. In total, 936,519 hospital admissions for ACEs occurred in the Italian population during the study period. A 4% reduction in hospital admissions for ACEs among persons aged less than 70 years was evident after the introduction of the ban (Rate Ratio [RR], 0.96; 95% Confidence Interval [CI], 0.95-0.98). No effect was found among persons aged at least 70 years (RR 1.00; 95% CI 0.99-1.02). Effect modification by age was further suggested by analyses using narrower age categories. CONCLUSIONS: Smoke-free policies can constitute a simple and inexpensive intervention for the prevention of cardiovascular diseases and thus should be included in prevention programmes.

Sample selection and validity of exposure-disease association estimates in cohort studies.

BACKGROUND: Participants in cohort studies are frequently selected from restricted source populations. It has been recognised that such restriction may affect the study validity. OBJECTIVES: To assess the bias that may arise when analyses involve data from cohorts based on restricted source populations, an area little studied in quantitative terms. METHODS: Monte Carlo simulations were used, based on a setting where the exposure and one risk factor for the outcome, which are not associated in the general population, influence selection into the cohort. All the parameters involved in the simulations (ie, prevalence and effects of exposure and risk factor on both the selection and outcome process, selection prevalence, baseline outcome incidence rate, and sample size) were allowed to vary to reflect real life settings. RESULTS: The simulations show that when the exposure and risk factor are strongly associated with selection (ORs of 4 or 0.25) and the unmeasured risk factor is associated with a disease HR of 4, the bias in the estimated log HR for the exposure-disease association is ±0.15. When these associations decrease to values more commonly seen in epidemiological studies (eg, ORs and HRs of 2 or 0.5), the bias in the log HR drops to just ±0.02. CONCLUSIONS: Using a restricted source population for a cohort study will, under a range of sensible scenarios, produce only relatively weak bias in estimates of the exposure-disease associations.

Differences in citation rates by country of origin for papers published in top-ranked medical journals: do they reflect inequalities in access to publication?

BACKGROUND: The acceptance of a paper in a top-ranked journal depends on the importance of the study, and should not depend on its country of origin. If the papers' citation rate is a proxy for their importance, and the threshold for acceptance is unrelated to the country of origin, papers from different countries published in the same journal should have a similar number of citations. Conversely, if the threshold is lowered for some countries, their papers will have a lower mean citation rate. METHODS: The number of citations and the corresponding author's country were obtained for 4724 papers published between 1998 and 2002 in the British Medical Journal, the Lancet, Journal of the American Medical Association and New England Journal of Medicine. Countries were grouped according to the World Bank classification and geographical location: low-middle income countries; high-income European countries; high-income non-European countries; UK and USA. The probability of papers being poorly cited by country of origin was estimated, using domestic papers (British papers published in British journals and US papers published in US journals) as the reference. RESULTS: Compared with domestic papers, the OR of being poorly cited was 0.67 (95% CI 0.55 to 0.81) for papers from high-income European countries, 0.97 (0.76 to 1.24) for papers from high-income non-European countries and 1.93 (1.28 to 2.89) for papers from low-middle income countries. CONCLUSIONS: Papers from different countries published in the same journal have different citation rates. This may reflect difficulties for researchers from some countries to publish their research in leading medical journals.

Cardiovascular benefits of smoking regulations: The effect of decreased exposure to passive smoking.

OBJECTIVES: Decreases in population rates of acute myocardial infarction (AMI) have been repeatedly seen in the first months after the introduction of regulations banning smoking in public places. By decreasing the exposure to passive smoking and its acute cardiovascular effects, smoking regulations may cause an immediate drop in AMI incidence, beginning from the initial days after their introduction. Using simulations, we quantified this expected decrease. METHODS: Expected AMI decreases were estimated using several parameters, including prevalence of exposure to passive and active smoking, relative risks of AMI associated with active and passive smoking, decrease in exposure to passive smoking after the introduction of the regulation, and level of susceptibility of active smokers to exposure to passive smoking. RESULTS: After evaluating several possible combinations of these parameters, we found that AMI reductions of 5-15% seem likely. For example, a scenario with a population average of 5 hours per week of overall exposure to passive smoking, a 50% reduction in this exposure after the introduction of the regulation, an acute relative risk (RR) of AMI of 4.5 in the first hour after passive smoking exposure, and similar susceptibility to passive smoking among both active and passive smokers translates into a 8.6% decrease in AMI. CONCLUSIONS: Smoking regulations can cause immediate and relevant decreases in AMI through the prevention of exposure to passive smoking.

Analysis of nonresponse in the assessment of health-related quality of life of childhood cancer survivors.

The aim of this study was to compare the characteristics of respondents and nonrespondents in a survey of childhood cancer survivors recorded in the Childhood Cancer Registry of Piedmont and their current primary care general practitioners. Eligible subjects were identified from the Childhood Cancer Registry of Piedmont and the referring general practitioners were traced through the National Health Service. A postal questionnaire was sent both to childhood cancer survivors and to their general practitioners. Prevalence odds ratios were estimated for demographic and clinical characteristics in survivors and for demographic characteristics in general practitioners. A total of 1005 childhood cancer survivors and 857 general practitioners (132 of them had two or more cancer survivors in care) were included in the study. Completed questionnaires were obtained from 691 survivors (69%) and 615 general practitioners (72%). For survivors, the only associations with nonresponse were for age 35-44 years [prevalence odds ratio: 0.53 (95% confidence interval: 0.33-0.85)], being married [prevalence odds ratio: 1.45 (95% confidence interval: 0.96-2.18)] and diagnosis after 1977 [prevalence odds ratio: 0.66 (95% confidence interval: 0.42-1.03)]. For general practitioners, the only associations were for male sex [prevalence odds ratio: 1.62 (95% confidence interval: 1.13-2.32)] and place of work outside of the city of Turin [prevalence odds ratio: 1.93 (95% confidence interval: 1.07-3.47)]; furthermore associations were relatively weak. An association was also found between nonresponse in survivors and nonresponse in their general practitioners [prevalence odds ratio: 3.40 (95% confidence interval: 2.54-4.56)]. In conclusion, apart from age, marital status and period of diagnosis, there were little differences between respondent and nonrespondents, for the considered clinical and demographical characteristics. Participation of survivors and their general practitioners correlated, suggesting that involvement of the general practitioners in the study may be a method to increase participation of survivors of childhood cancers.

Short-term effects of Italian smoking regulation on rates of hospital admission for acute myocardial infarction.

AIMS: We used the hospital discharge records of Piedmont region (northern Italy) to evaluate whether a national law banning smoking in public resulted in a short-term reduction in hospital admissions for acute myocardial infarction (AMI). METHODS AND RESULTS: Rates of admission for AMI before the ban (October-December 2004) and during the ban (February-June 2005) were analysed. Each period was compared with the corresponding period 12 months before. Among persons aged under 60, the number of admissions for AMI decreased significantly after the introduction of the ban: from 922 cases in February-June 2004 to 832 cases in February-June 2005 (sex- and age-adjusted rate ratio, 0.89; 95% confidence interval, 0.81-0.98). No decrease was seen before the ban. No effect was found among persons aged at least 60. We estimated that the observed reduction in active smoking after the introduction of the ban could account for a 0.7% decrease in admissions for AMI during the study period, suggesting that most of the observed effect (11%) might be due to the reduction of passive smoking. CONCLUSION: Our study, based on a population of about 4 million inhabitants, suggests that smoke-free policies may result in a short-term reduction in admissions for AMI.