Multivariate Analysis and Spatial/Temporal Scales: Real and Complex Models

Introduction We do not want to open the Pandora's box of space-time models, i.e. we shall not consider covariance functions (or variograms) which depend on both space and time. The two classes of models, the LMC and the BMC, are suitable to be applied either to multivariate spatial data or to multiple/multivariate time series. The LMC implies even cross covariance functions. It can thus be formulated in a framework with variograms implying a less restrictive definition of stationarity: only the increments of the random functions are assumed to be jointly stationary. The use of cross variograms (even cross covariance functions) excludes deferred correlations which are however less likely to occur between spatial variables. Thus the LMC underlying a variogram matrix model can be appropriate for spatial multivariate data. The BMC allows for uneven cross covariance functions. It is interesting for modeling second order stationary multivariate spatial data as well as mul

Effect of occupational safety and health education received during schooling on the incidence of workplace injuries in the first 2 years of occupational life: a prospective study

International audienceOBJECTIVES: This study aimed to determine the effect of occupational safety and health (OSH) education during formal schooling on the incidence of workplace injuries (WIs) in young people starting their careers. We hypothesised that young people who had received OSH education during their schooling would have fewer WIs than those who received no OSH education. Secondary objectives focused on the effect of 'first aid at work' training during schooling and the conditions encountered on arrival in the company (occupational hazard information, safety training and job task training) on WI occurrence.DESIGN: Prospective cohort study.PARTICIPANTS: From 2009 to 2012, French apprentices and students at the end of their schooling and starting their careers were included.OUTCOMES: Occurrence of WIs.METHODS: At the time of inclusion, information about school courses and personal characteristics were collected, and subsequent half-yearly contacts gathered information relating to work and personal data. During the 2-year follow-up, WIs were directly reported by participants and were identified by searching the French National Health Insurance Funds' databases listing compulsory WI declarations.RESULTS: 755 participants reported holding 1290 jobs. During follow-up, 158 WIs were identified, corresponding to an incident rate of 0.12 (0.10 to 0.14) WIs per full-time worker. Subjects who reported having received OSH education at school had two times less WIs than those declaring not having received OSH education (incidence rate ratio (IRR) 0.51, 0.00 to 0.98). A lower WI risk was observed for participants who received the 'first aid at work' training (IRR=0.68, 0.00 to 0.98). The conditions on arrival in company were not associated with WIs occurrence.CONCLUSION: In France, the OSH education provided to apprentices and students is mostly broader than the specific risks related to future jobs. Our results highlight the advantages of reinforcing this approach.L’objectif de cette étude était de déterminer l’effet de l’enseignement en santé et sécurité au travail (SST), reçu au cours de la formation initiale, sur la survenue d’accident du travail (AT) chez les jeunes qui entrent dans la vie active. Les auteurs sont partis de l’hypothèse que les jeunes qui ont reçu une formation SST au cours de leurs études scolaires pourraient avoir moins d’AT que ceux qui n’ont pas été formés. Les objectifs secondaires portaient sur les effets d’une formation aux premiers secours au travail et des conditions à l’arrivée dans l’entreprise (information sur les risques professionnels, formation à la sécurité, formation par un « parrain ») sur la survenue des AT. Il s’agissait d’une étude de cohorte prospective menée sur une période de 2 années. De 2009 à 2012, des apprentis et des étudiants français en fin de scolarité et débutant une vie professionnelle ont été inclus. Au moment de l’inclusion dans l’étude, un questionnaire a recueilli des informations sur la scolarité et des caractéristiques individuelles, et un questionnaire de suivi, complété tous les six mois pendant deux ans a recueilli des informations sur le travail et des données personnelles. La survenue d’accident du travail au cours du suivi a été identifiée par la déclaration des jeunes et via les bases de données de déclaration obligatoire des accidents du travail gérées par les caisses régionales d’assurance maladie. 755 participants ont déclaré avoir exercé 1 290 emplois. Au cours de la période de suivi, 158 AT ont été identifiés, correspondant à un taux incident de 0,12 (0,10 à 0,14) AT par salarié temps plein. Les sujets qui ont déclaré avoir reçu un enseignement SST à l’école avaient 2 fois moins d’accidents du travail que ceux qui ont déclaré ne pas en avoir reçu. Un risque d’AT plus faible était observé chez ceux qui avaient bénéficié d’une formation aux premiers secours au travail. Les conditions d’intégration dans l’entreprise n’étaient pas associées à la survenue des AT. En conclusion, en France, l’enseignement SST dispensé aux apprentis et aux étudiants de manière plus large que les risques spécifiques de leurs futurs emplois. Ces résultats soulignent les avantages de renforcer cette approche

Net survival estimation with stns

In this article, we introduce a new Stata command to estimate the net survival function and the net cumulative hazard. The command includes graphic facilities. It was designed to have a similar syntax to sts, the Stata command dedicated to estimate survival and related functions. We present two examples to illustrate the use of this new command

Longitudinal predictors of bronchial hyperresponsiveness and FEV1 decline in bakers

International audienceObjective To determine long-term predictors of bronchial hyperresponsiveness (BHR) and forced expiratory volume in one second (FEV1) decline.Methods A longitudinal study in 110 bakers in 4 industrial bakeries and 38 non-exposed workers was conducted at the workplace with a mean of 3.3 visits per subject over a period of 13 years and a mean duration of follow-up of 6 years in bakers and 8 years in non-exposed subjects. A respiratory health questionnaire was administered; occupational allergen skin prick tests, spirometry and a methacholine bronchial challenge test were performed at each visit. In each bakery, full-shift dust samples of the inhalable fraction were obtained in order to assess the exposure of each job assignment. The repeated measurements of BHR and FEV1 were analyzed using mixed effects logistic and linear regression models in subjects seen at least twice.Results BHR, respiratory symptoms and their simultaneous occurrence depended on the duration of exposure. FEV1 significantly decreased with duration of exposure and BHR at a preceding visit. This result persisted when adjusting for the effect of BHR at the current visit. The measured exposure levels were not a significant predictor for any outcome. Occupational sensitization was only a predictor of a decline in FEV1 when duration of exposure was not included.Conclusion In flour-exposed industrial bakers, length of exposure and smoking are long-term determinants of BHR and of the decrease in FEV1. BHR at a preceding visit predicted lower FEV1 even when accounting for the effect of BHR at the current visit

Low Back Pain and Upper-Extremity Musculoskeletal Disorders in French Postal Workers Driving Light-Duty Vehicles for Mail and Parcel Delivery

Occupational driving of light-duty vehicles (LDVs) became increasingly important in parcel delivery faced with the explosive growth of e-commerce. Since musculoskeletal disorders (MSDs) represent the most reported driving-related health problem, we aimed to analyze the risk of low back pain (LBP) and upper-extremity musculoskeletal disorders (UEMSDs) associated with driving LDVs for parcel delivery. In 306 postal workers exposed to driving and 100 unexposed workers, information on occupational driving, physical/psychosocial constraints, and work organization were collected via a questionnaire. MSDs were assessed using the Nordic Questionnaire, 14 additional questions regarding LBP, and a standardized clinical examination for UEMSDs. Statistical modeling consisted of multivariable logistic regression for UEMSDs and the item response theory approach for LBP. UEMSDs were associated with the distance of rural rounds and inversely associated with urban/mixed delivery rounds. Handling heavy loads was associated with LBP, and high physical demands during delivery rounds were related to MSDs. Karasek dimensions and mobbing actions were associated with MSDs. Work recognition, driving training, using an automatic gearbox, and the utilization of additional staff during peak periods were inversely associated with MSDs. Our results suggest that the distance driven in rural settings and high physical demands were associated with MSDs, while some organizational factors could protect from MSDs

Effects of plant features on symptoms and airway inflammation in compost workers followed over 18 months

International audienceThis study investigated the plant features associated with increased irritation symptoms and levels of inflammation markers among compost workers (CWs). Ninety CWs were followed over 18 months, using questionnaires on respiratory symptoms, fractional exhaled nitric oxide measurements, spirometry, a methacholine bronchial challenge test, and quantification of specific immunoglobulins E (IgE) and G. CWs in plants processing the highest quantities of waste exhibited more airway irritation symptoms. So did the CWs in partially and fully indoor plants as compared to those in plants entirely outdoors. Working in sewage sludge versus green waste plants and having a high level of exposure were associated with higher levels of different IgE. The duration of employment decreased the FEV1 by 16 ml per year. Working in an indoor plant is linked to symptoms and inflammation markers in CWs

Gene Expression in Proliferating Cells of the Dinoflagellate Alexandrium catenella (Dinophyceae)▿ †

Understanding the conditions leading to harmful algal blooms, especially those produced by toxic dinoflagellate species, is important for environmental and health safety. In addition to investigations into the environmental conditions necessary for the formation of toxic blooms, we postulate that investigating gene expression in proliferating cells is essential for understanding bloom dynamics. Expressed sequence tags were produced from cultured cells of the toxic dinoflagellate Alexandrium catenella sampled during the initiation phase of growth using Sanger's method and by 454 pyrosequencing. A significant proportion of identified genes (ca. 25%) represented enzymes and proteins that participate in a variety of cellular regulatory mechanisms that may characterize proliferating cells, e.g., control of the cell cycle and division, regulation of transcription, translation and posttranslational protein modifications, signaling, intracellular trafficking, and transport. All of the several genes selected for gene expression assays due to their involvement in metabolism and the cell cycle were overexpressed during exponential growth. These data will be useful for investigating the mechanisms underlying growth and toxin production in toxic Alexandrium species and for studying and monitoring the development of toxic blooms

Geographical Heterogeneity of Multiple Sclerosis Prevalence in France.

INTRODUCTION:Geographical variation in the prevalence of multiple sclerosis (MS) is controversial. Heterogeneity is important to acknowledge to adapt the provision of care within the healthcare system. We aimed to investigate differences in prevalence of MS in departments in the French territory. METHODS:We estimated MS prevalence on October 31, 2004 in 21 administrative departments in France (22% of the metropolitan departments) by using multiple data sources: the main French health insurance systems, neurologist networks devoted to MS and the Technical Information Agency of Hospitalization. We used a spatial Bayesian approach based on estimating the number of MS cases from 2005 and 2008 capture-recapture studies to analyze differences in prevalence. RESULTS:The age- and sex-standardized prevalence of MS per 100,000 inhabitants ranged from 68.1 (95% credible interval 54.6, 84.4) in Hautes-Pyrénées (southwest France) to 296.5 (258.8, 338.9) in Moselle (northeast France). The greatest prevalence was in the northeast departments, and the other departments showed great variability. DISCUSSION:By combining multiple data sources into a spatial Bayesian model, we found heterogeneity in MS prevalence among the 21 departments of France, some with higher prevalence than anticipated from previous publications. No clear explanation related to health insurance coverage and hospital facilities can be advanced. Population migration, socioeconomic status of the population studied and environmental effects are suspected