New Insights into Handling Missing Values in Environmental Epidemiological Studies

International audienceMissing data are unavoidable in environmental epidemiologic surveys. The aim of this study was to compare methods for handling large amounts of missing values: omission of missing values, single and multiple imputations (through linear regression or partial least squares regression), and a fully Bayesian approach. These methods were applied to the PARIS birth cohort, where indoor domestic pollutant measurements were performed in a random sample of babies' dwellings. A simulation study was conducted to assess performances of different approaches with a high proportion of missing values (from 50% to 95%). Different simulation scenarios were carried out, controlling the true value of the association (odds ratio of 1.0, 1.2, and 1.4), and varying the health outcome prevalence. When a large amount of data is missing, omitting these missing data reduced statistical power and inflated standard errors, which affected the significance of the association. Single imputation underestimated the variability, and considerably increased risk of type I error. All approaches were conservative, except the Bayesian joint model. In the case of a common health outcome, the fully Bayesian approach is the most efficient approach (low root mean square error, reasonable type I error, and high statistical power). Nevertheless for a less prevalent event, the type I error is increased and the statistical power is reduced. The estimated posterior distribution of the OR is useful to refine the conclusion. Among the methods handling missing values, no approach is absolutely the best but when usual approaches (e.g. single imputation) are not sufficient, joint modelling approach of missing process and health association is more efficient when large amounts of data are missing

Exposition domestique à des polluants chimiques de l'air intérieur (modélisation et évaluation de l'impact sur la santé respiratoire chez le jeune enfant)

Problématique : La qualité de l air intérieur est devenue une préoccupation majeure de santé publique, en raison du temps passé à l intérieur des locaux et de la diversité des contaminants biologiques et des polluants chimiques présents. Objectifs : Il s agit de renseigner et de modéliser l exposition domestique à des polluants chimiques retrouvés dans l air intérieur et d en étudier le lien avec la morbidité respiratoire au cours de la première année de vie des nouveau-nés de la cohorte PARIS (Pollution and Asthma Risk : an Infant Study). Méthodes : À 1, 3, 6, 9 et 12 mois, des questionnaires sanitaires sont adressés aux parents pour renseigner la survenue des infections des voies respiratoires et des symptômes évocateurs d asthme (sifflements, toux sèche nocturne, etc.). Des questionnaires environnementaux sont envoyés en parallèle pour documenter le cadre et le mode de vie des enfants. Pour pallier l imprécision résultant d une évaluation de l exposition aux polluants de l air intérieur par simple questionnaire, des investigations environnementales complémentaires ont été conduites, à 1, 6, 9 et 12 mois, au domicile d un échantillon aléatoire de 196 nouveau-nés de la cohorte PARIS et dans des crèches parisiennes fréquentées par ces enfants. Les données issues des mesurages domestiques répétés ont été confrontées aux données recueillies par questionnaires afin d établir des modèles prédictifs s concentrations domestiques annuelles de polluants. Ces modèles ont ensuite été appliqués à l ensemble des logements fréquentés par les enfants de la cohorte afin de les classer au regard de leur exposition domestique annuelle pour étudier l impact sanitaire de cette exposition. Résultats : Les modèles prédictifs des concentrations mesurées ont permis d identifier les déterminants des niveaux de formaldéhyde, de dioxyde d azote, de toluène et de tétrachloroéthylène : les sources continues et leur caractère récent (panneaux de particules, parquet vitrifié, stratifié, flottant et peinture), les sources discontinues (combustion et proximité au pressing) et les paramètres d aération et de ventilation conditionnant l entrée ou la sortie du polluant selon leur origine dominante. Au cours de la première année de vie, près d un enfant sur deux présente une infection des voies respiratoires basses, 14,8 % une toux sèche nocturne. Concernant l impact sanitaire de l exposition aux polluants chimiques, après ajustement sur l ensemble des facteurs de risque, seule l exposition domestique au formaldéhyde majore la survenue des infections et plus particulièrement des infections sifflantes. L exposition au formaldéhyde est aussi associée à la toux sèche nocturne et plus particulièrement chez les enfants sans antécédents parentaux d allergie. Conclusion : Une exposition domestique aux polluants chimiques de l air intérieur, tels que le formaldéhyde, peut être associée à la morbidité respiratoire du jeune enfant. Ces résultats viennent appuyer les mesures prises par les pouvoirs publics concernant les émissions des matériauxThere is a growing public health concern about indoor air quality due to the time spent indoors and the presence of numerous biological and chemical pollutants. Aims: To assess indoor chemical pollutant levels, to model domestic exposure and to examine the impact of indoor chemical pollutants on the respiratory health of infants from the PARIS birth cohort, during their first year of life. Methods: Multiple self-administered questionnaires were used to gather information from parents about respiratory infections and asthma-like symptoms (wheezing, nocturnal dry cough. . . ) in their infants at ages 1, 3, 6, 9 and 12 months. Details about home characteristics and family living conditions were also collected by phone interview when the child was 1 month old, and mailed questionnaires captured changes at 3, 6, 9 and 12 months. Pollutant air sampling (aldehyde, volatile organic compound, nitrogendioxide and nicotine) were conducted at 1, 6, 9 and 12 months in the bedrooms of a subset of randomly selected 196infants. Repeated pollutant measurements were joined with interview and questionnaire information to construct annual pollutant exposure models for all infants. Furthermore, an environmental investigation was performed in Parisian child day care centers to document chemical exposure levels. Results: Formaldehyde, toluene, nitrogen dioxide and perchlororethylene level determinants: continuous sources (particleboard, varnished parquet floor, wall coating), discontinuous sources (combustion, dry cleaning facilities) and aeration parameters were identified. At one year, around half of babies experienced at least one lower respiratory infection, and nearly half of those infections included wheezing, 14,8 % of babies suffered from a nocturnal dry cough. After known risk factors were considered, lower respiratory infections were associated with estimated formaldehyde levels, and formaldehyde exposure is also related to nocturnal dry cough, especially in infants without parental history of allergy. Conclusion: This study shows that formaldehyde exposure in early life is associated with respiratory health in infants, promoting public actions regarding emissions from materialsPARIS5-Bibliotheque electronique (751069902) / SudocSudocFranceF

Formaldehyde Exposure and Lower Respiratory Infections in Infants: Findings from the PARIS Cohort Study

Background: Certain chemical pollutants can exacerbate lower respiratory tract infections (LRIs), a common childhood ailment. Although formaldehyde (FA) is one of the most common air pollutants found in indoor environments, its impact on infant health is uncertain

Lack of interest in physical activity : individual and environmental attributes in adults across Europe : the SPOTLIGHT project

A considerable proportion of European adults report little or no interest in physical activity. Identifying individual-level and environmental-level characteristics of these individuals can help designing effective interventions and policies to promote physical activity. This cross-sectional study additionally explored associations between level of interest and physical activity, after controlling for other individual and environmental variables. Measures of objective and perceived features of the physical environment of residence, self-reported physical activity and other lifestyle behaviors, barriers towards physical activity, general health, and demographics were obtained from 5205 European adults participating in the 2014 online SPOTLIGHT survey. t-Tests, chi-square tests, and generalized estimating equations with negative binomial log-link function were conducted. Adults not interested in physical activity reported a higher BMI and a lower self-rated health, were less educated, and to a smaller extent female and less frequently employed. They were more prone to have less healthy eating habits, and to perceive more barriers towards physical activity. Only minor differences were observed in environmental attributes: the non-interested were slightly more likely to live in neighborhoods objectively characterized as less aesthetic and containing more destinations, and perceived as less functional, safe, and aesthetic. Even after controlling for other individual and environmental factors, interest in physical activity remained a significant correlate of physical activity, supporting the importance of this association. This study is among the first to describe characteristics of individuals with reduced interest in physical activity, suggesting that (lack of) interest is a robust correlate of physical activity in several personal and environmental conditions

Physical Environmental Correlates of Domain-Specific Sedentary Behaviours across Five European Regions (the SPOTLIGHT Project)

BACKGROUND: The relation between neighbourhood environmental factors and domain-specific sedentary behaviours among adults remains unclear. This study firstly aims to examine the association of perceived and objectively measured neighbourhood safety, aesthetics, destinations and functionality with transport-related, work-related and leisure-time sedentary behaviour. Secondly, the study aims to assess whether these associations are moderated by age, gender or educational level. METHODS: In 60 randomly sampled neighbourhoods from 5 urban regions in Europe (Ghent and suburbs, Paris and inner suburbs, Budapest and suburbs, the Randstad, and Greater London), a virtual audit with Google Street View was performed to assess environmental characteristics. A total of 5,205 adult inhabitants of these neighbourhoods reported socio-demographic characteristics, sedentary behaviours, and neighbourhood perceptions in an online survey. Generalized linear mixed models were conducted to examine associations between physical environmental neighbourhood factors and sedentary behaviours. Interaction terms were added to test the moderating role of individual-level socio-demographic variables. RESULTS: Lower levels of leisure-time sedentary behaviour (i.e. all leisure activities except television viewing and computer use) were observed among adults who perceived greater numbers of destinations such as supermarkets, recreational facilities, or restaurants in their neighbourhood, and among adults who lived in a neighbourhood with more objectively measured aesthetic features, such as trees, water areas or public parks. Lower levels of work-related sedentary behaviour were observed among adults who perceived less aesthetic features in their neighbourhood, and among adults who lived in a neighbourhood with less objectively measured destinations. Both age, gender and educational level moderated the associations between neighbourhood environmental factors and sedentary behaviours. CONCLUSION: Preliminary evidence was found for associations between neighbourhood environmental factors and domain-specific sedentary behaviours among adults. However, these associations varied according to objective or subjective environmental measures. More research is needed to confirm and clarify the associations

Physical-activity trajectories during childhood and lung function at 15 years: findings from the ALSPAC cohort.

BACKGROUND:Although physical activity has many known health benefits, its association with lung function in childhood/adolescence remains unclear. We examined the association of physical-activity trajectories between 11 and 15 years with lung function at 15 years in 2266 adolescents. METHODS:A population-based cohort of 14 305 singleton births alive at 1 year was recruited in the UK population-based Avon Longitudinal Study of Parents and Children cohort. Physical activity (counts/minute and moderate-to-vigorous physical activity) was assessed for 7 days using an accelerometer at 11, 13 and 15 years. We identified sex-specific physical-activity trajectories applying K-means for longitudinal data in children with at least two accelerometer measurements (n = 3584). We then estimated the sex-specific associations of these trajectories with post-bronchodilation lung-function parameters using multivariable linear-regression models (n = 2266, 45% boys). RESULTS:Fewer than 7% of participants met the WHO physical-activity recommendations (i.e. daily average of at least 60 minutes of moderate-to-vigorous physical activity). Boys were substantially more active than girls. In both sexes, we identified three distinct physical-activity trajectories ('low': 39.8% boys, 45.8% girls; 'moderate': 42.9% boys, 41.4% girls; and 'high' physical activity: 17.3% boys, 12.8% girls). Girls in the moderate and high physical-activity trajectories had 0.11 L [95% confidence interval (CI): 0.04-0.19] and 0.15 L (95% CI: 0.03-0.26) higher forced vital capacity than their less-active peers. No association was observed in boys. CONCLUSIONS:Higher childhood physical activity relates to higher lung-function levels in adolescent girls. A better understanding of the mechanisms underlying this association should be pursued

Built environmental correlates of cycling for transport across Europe.

This cross-sectional study aimed to determine which objective built environmental factors, identified using a virtual neighbourhood audit, were associated with cycling for transport in adults living in five urban regions across Europe. The moderating role of age, gender, socio-economic status and country on these associations was also investigated. Overall, results showed that people living in neighbourhoods with a preponderance of speed limits below 30km/h, many bicycle lanes, with less traffic calming devices, more trees, more litter and many parked cars forming an obstacle on the road were more likely to cycle for transport than people living in areas with lower prevalence of these factors. Evidence was only found for seven out of 56 possible moderators of these associations. These results suggest that reducing speed limits for motorized vehicles and the provision of more bicycle lanes may be effective interventions to promote cycling in Europe

Childhood Body Composition Trajectories and Adolescent Lung Function. Findings from the ALSPAC study.

Rationale: Body composition changes throughout life may explain the inconsistent associations reported between body mass index and lung function in children. Objectives: To assess the associations of body weight and composition trajectories from 7 to 15 years with lung function at 15 years and lung function growth between 8 and 15 years. Methods: Sex-specific body mass index, lean body mass index, and fat mass index trajectories were developed using Group-Based Trajectory Modeling on data collected at least twice between 7 and 15 years from 6,964 children (49% boys) in the UK Avon Longitudinal Study of Parents and Children birth cohort. Associations of these trajectories with post-bronchodilation lung function parameters at 15 years and with lung function growth rates from 8 to 15 years were assessed using multivariable linear regression models, stratified by sex, in a subgroup with lung function data (n = 3,575). Measurements and Main Results: For all body mass measures we identified parallel trajectories that increased with age. There was no consistent evidence of an association between the body mass index trajectories and lung function measures. Higher lean body mass index trajectories were associated with higher levels and growth rates of FVC, FEV₁, and forced expiratory flow, midexpiratory phase in both sexes (e.g., boys in the highest lean body mass index trajectory had on average a 0.62 L [95% confidence interval, 0.44-0.79; P trend < 0.0001] higher FVC at 15 yr than boys in the lowest trajectory). Increasing fat mass index trajectories were associated with lower levels and growth rates of FEV₁ and forced expiratory flow, midexpiratory phase only in boys and lower levels of FEV₁/FVC in both sexes. Conclusions: Higher lean body mass during childhood and adolescence is consistently associated with higher lung function at 15 years in both sexes, whereas higher fat mass is associated with lower levels of only some lung function parameters

The associations between domain-specific sedentary behaviours and dietary habits in European adults: a cross-sectional analysis of the SPOTLIGHT survey

BACKGROUND: Sedentary behaviour has been associated with obesity and related chronic diseases. Disentangling the nature of this association is complicated due to interactions with other lifestyle factors, such as dietary habits, yet limited research has investigated the relation between domain-specific sedentary behaviours and dietary habits in adults. The aim of this paper was to examine the association between domain-specific sedentary behaviours and dietary habits in adults and to test the moderating effect of age and gender on this association. METHODS: A total of 6,037 participants from five urban regions in Europe completed an online survey, of which 6,001 were included in the analyses. Multilevel mixed-effects logistic regression analyses were used to examine main associations and interaction effects. RESULTS: All domain-specific sedentary behaviours, except transport-related sitting time, were significantly related to dietary habits. In general, having a higher sitting time was related to having less healthy dietary habits, especially for television viewing. Gender did not moderate any of the relations, and age was only a significant moderator in the relation between other leisure sitting time and alcohol consumption. CONCLUSION: Domain-specific sitting behaviours were related to unhealthy dietary behaviours. However, the small effect sizes suggest that individual level behavioural interventions focusing on sedentary behaviour will not be sufficient to improve dietary habits. The fact that almost none of the associations were moderated by age or gender suggests that these associations, and possibly also the effects of interventions targeting both behaviours, may hold across age and gender groups