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L Filleul

Publications and source records attributed to L Filleul.

At least 19 recordsLinked to original sources
PubMed2006

Nested frailty models using maximum penalized likelihood estimation.

The frailty model is a random effect survival model, which allows for unobserved heterogeneity or for statistical dependence between observed survival data. The nested frailty model accounts for the hierarchical clustering of the data by including two nested random effects. Nested frailty models are particularly appropriate when data are clustered at several hierarchical levels naturally or by design. In such cases it is important to estimate the parameters of interest as accurately as possible by taking into account the hierarchical structure of the data. We present a maximum penalized likelihood estimation (MPnLE) to estimate non-parametrically a continuous hazard function in a nested gamma-frailty model with right-censored and left-truncated data. The estimators for the regression coefficients and the variance components of the random effects are obtained simultaneously. The simulation study demonstrates that this semi-parametric approach yields satisfactory results in this complex setting. In order to illustrate the MPnLE method and the nested frailty model, we present two applications. One is for modelling the effect of particulate air pollution on mortality in different areas with two levels of geographical regrouping. The other application is based on recurrent infection times of patients from different hospitals. We illustrate that using a shared frailty model instead of a nested frailty model with two levels of regrouping leads to inaccurate estimates, with an overestimation of the variance of the random effects. We show that even when the frailty effects are fairly small in magnitude, they are important since they alter the results in a systematic pattern.

Adult↗
PubMed2006

[Estimating mortality attribuable to PM10 particles in 9 French cities participating in the European programme Apheis].

The relationship between air pollution and mortality is now admissible with a sufficiently high level of causality proven. This link allows for health impact assessment to be carried out with a significant degree of accuracy, such as the case for the results which are presented here from the nine French cities involved in the Apheis programme. This health impact assessment is based on the methodology developed by the World Health Organization. The number of avoidable deaths is contained between categories ranging from 2.0 to 4.3, 4.0 to 8.9, and from 15.0 to 31.5 per 100,000 inhabitants according to very short term effects, short term effects and long term effects, respectively. There are two scenarios which can be envisioned for the reduction of fine particles levels which are capable of obtaining similar results for both very short term and short term effects. The first involves diminishing the daily concentrations which are above 20 microg/m3 until they reach this value, and the second entails systematically decreasing the daily levels by 5 microg/m3. The first strategy of reducing values to stabilize at 20 microg/m3 has been shown to be the one most favourable and promising for the long term effects. This strategy therefore confirms the reliability and strength of the recommendation formulated at the national level.

Aged↗
PubMed2006

Health effects of PM10 air pollution in a low-income country: the case of Algiers.

SETTING: Although there are proven risk factors related to air pollution, the prevalent situation in low-income countries is not well known. OBJECTIVE: To quantify the health impacts associated with particulate air pollution in the city of Algiers. DESIGN: Descriptive study to evaluate a health impact assessment (HIA) approach based on a dose-response curve from the literature. A study area was defined around an air quality monitoring site in Algiers. Daily health data were obtained from a network of physicians practising in out-patient health centres. RESULTS: Over the period studied, the number of consultations for respiratory reasons attributable to PM10 exposure was 439, representing 4.5% of all health events observed. Different scenarios were examined, showing that a reduction in ambient levels of PM10 would be accompanied by important public health gains. CONCLUSION: The study allowed us to test the applicability of the HIA approach in a low-income country and to confirm the interest of the approach. Although the estimation of dose-response functions obeys a complex methodology, the HIA is an alternative that constitutes an important decision-making tool.

Air Pollutants↗
PubMed2005

Twenty five year mortality and air pollution: results from the French PAARC survey.

AIMS AND METHODS: Long term effects of air pollution on mortality were studied in 14,284 adults who resided in 24 areas from seven French cities when enrolled in the PAARC survey (air pollution and chronic respiratory diseases) in 1974. Daily measurements of sulphur dioxide, total suspended particles, black smoke, nitrogen dioxide, and nitric oxide were made in 24 areas for three years (1974-76). Cox proportional hazards models controlling for individual confounders (smoking, educational level, body mass index, occupational exposure) were applied, and frailty models used to take into account spatial correlation. Indicators of air pollution were the mean concentration. RESULTS: Models were run before and after exclusion of six area monitors influenced by local traffic (NO/NO2 >3 in ppb). After exclusion of these areas, analyses showed that adjusted risk ratios (95% CI) for TSP, BS, NO2, and NO for non-accidental mortality were 1.05 (1.02 to 1.08), 1.07 (1.03 to 1.10), 1.14 (1.03 to 1.25), and 1.11 (1.05 to 1.17) for 10 microg/m3 respectively. Consistent patterns for lung cancer and cardiopulmonary causes were observed. CONCLUSIONS: Urban air pollution assessed in the 1970s was associated with increased mortality over 25 years in France.

Adult↗
PubMed2005

An imported case of canine rabies in Aquitaine: investigation and management of the contacts at risk, August 2004-March 2005.

In August 2004, a case of rabies was diagnosed in a puppy that had been illegally imported from Morocco to Bordeaux (France). Because a great number of people and animals were thought to have come into contact with the puppy, extensive tracing measures were implemented, and an international alert was launched to trace and treat the contacts at risk. One hundred and eighty seven people received post-exposure treatment, eight of whom also received serovaccination, and 57 animals known to have been exposed to the puppy were tested. Six months after the death of the rabid animal, none of the people treated showed any signs of rabies, nor was any secondary animal case reported. The management of this crisis highlights the importance of the role of a rapid alert system at European level. Strict application of sanitary control regulations is essential for animals introduced into EU countries, and all necessary information must be made available to EU residents travelling to rabies enzootic areas.

Adolescent↗
PubMed2004

[The impact of air pollution on health. The "Programme de Surveillance Air et Santé 9 villes" (Air and Health surveillance program in 9 cities)].

OBJECTIVES: To quantify the short term effects of air pollution on mortality and hospitalisation for cardiovascular or respiratory disorders in the nine French cities (Bordeaux, Le Havre, Lille, Lyon, Marseille, Paris, Rouen, Strasbourg and Toulouse) of the Surveillance Air et Santé program. METHODS: Data were available on mortality and hospitalisation were available, respectively, from 1990 to 1997 and 1995 to 1999. Exposure data were the concentrations of sulphur dioxide, particles with a diameter of less than or equal to 10 mm, black smoke, nitrogen dioxide, ozone, and carbon monoxide. The analysis assessed the relationships, in each of the cities, between the daily numbers of deaths and hospitalisations and the daily levels of polluting agents, taking into account confounding factors. A combined relative risk was calculated for all the cities. The number of deaths and hospitalisations attributable to air pollution was then estimated for each of the cities, based on the relative risk. RESULTS: Significant relationships were found for mortality, from whatever cause, and for hospitalisations for respiratory disorders in children aged under 15. If the levels of air pollution were reduced to 10 microg/m3 in the nine cities, 2800 premature deaths and 750 hospitalisations for respiratory disorders in children would be avoided, every year. CONCLUSION: Today, it is possible to assess the benefits of reducing air pollution in terms of health in the short term. These analyses would provide a sanitary dimension to the strategies for the reduction of urban pollution on local and European level.

Adolescent↗
PubMed2004

[Air pollution and cardiovascular toxicity: known risks].

SUBJECT: Review of studies about epidemiological and physiopathological knowledge of ambient air particles short-term cardio-vascular effects. CURRENTS AND STRONG POINTS: Many studies, in contrasted countries for pollution's sources, meteorological conditions or socio-demographical characteristics, have shown health effects due to ambient air particles. After having studied mainly the respiratory effects of particulate air pollution, epidemiologists are now interested in the cardio-vascular effects of ambient air particles. In fact, serious effects seem to exist in fragile people which can get to emergency department visits, hospitalisation and even death. In addition, studies have shown less serious effects, but likely to be frequent (cardiac symptoms, and stoppages for cardio-vascular causes, notably). The exact mechanism by which particles have cardio-vascular adverse health effects is unknown, but experimental and epidemiological studies have led to several hypotheses: local pulmonary effects seem to be followed by systemic effects, which would be responsible for effects on the electrical activity of the heart through cardiac autonomic dysfunction and effects on the blood supply to the heart. The objective of this work is to summarise epidemiological and physiopathological knowledge about the cardio-vascular effects of ambient air particles. PROSPECTS AND PROJECTS: To evaluate the real importance of cardio-vascular effects due to particulate air pollution and to identify their exact mechanism, a more precise knowledge of detailed causes of deaths and hospitalisations and a better knowledge of less serious effects, but likely to be frequent, is necessary. Equally, a detailed identification of fragile people is essential for developing preventive actions.

Air Pollutants↗
PubMed2004

IgE level and Phadiatop in an elderly population from the PAQUID cohort: relationship to respiratory symptoms and smoking.

BACKGROUND: In the last decades in industrialized countries, the increase of life expectancy has resulted in an increase in the population of the elderly. However, little is known about the prevalence of allergies in the elderly population. The aim of the study was to investigate the specific relationship of serum IgE and Phadiatop, with asthma, rhinitis, and smoking in a sample of an elderly population. METHODS: Subjects from the Paquid cohort living in Gironde Department (age 65 years and over) in France were followed up since 1988 (PAQUID cohort). RESULTS: Among the randomized sample of 352 subjects, there were 158 men (45%) and 194 women (55%). The lowest levels of IgE were in subjects with chronic sputum; and in normal subjects (47.1 +/- 56.4 vs 56.2 +/- 73.9, NS). Multiple linear regression was performed with log(10) IgE values as a dependent variable and age, Phadiatop test, smoking, and respiratory symptoms independently in men and in women. In men, a significant relationship was observed between IgE values and Phadiatop test (P < 0.001), asthma history (P = 0.002), and smoking (P = 0.019). CONCLUSIONS: Respiratory allergy is present in persons >65 years of age. There is an association between smoking and IgE level independent of allergic reactivity to common allergens in the elderly.

Aged↗
PubMed2003

Risk factors among elderly for short term deaths related to high levels of air pollution.

BACKGROUND: Air pollution has been linked to increased rates of mortality, but little is known about individual characteristics related to the increase in risk. AIMS: To examine short term effects of air pollution on daily mortality in elderly people in Bordeaux and compare characteristics of subjects > or =65 years old who died with levels of particulate air pollution. METHODS: Daily mortality data from Bordeaux were used to determine the core model of mortality for the period 1988-97. The air pollution indicator was regressed on the core model of mortality, allowing control of the main effect modifiers and confounding factors of air pollution on the same day. The residual series of this regression model was classified from the lowest to the highest to determine "low level days" and "high level days". A sample of 1469 elderly people in a French cohort study were studied. RESULTS: From 1988 to 1997, 543 subjects died; 55 deaths were during days with low air pollution and 51 during days with high air pollution. Only gender differed significantly according to both types of days, with a proportion of women significantly higher in high air pollution days than men. After adjustment for smoking habits, the odds ratio was 5.2 for women. CONCLUSION: The risk of mortality between women and men was determined on days with "high air pollution levels" above the 50-90th centiles compared to below the 10th centile. No clear pattern was observed between days with low levels of air pollution and the different centiles of exposure.

Aged↗
PubMed2003

Long-term mortality among adults with or without asthma in the PAARC study.

The Pollution Atmosphérique et Affections Respiratoires Chroniques (PAARC; Air Pollution and Chronic Respiratory Diseases) study provided the opportunity to examine the 25-yr mortality of 940 asthmatic adults drawn from a large population-based sample of 14,267 adults investigated during 1974-1976 in seven French cities. Vital statistics were collected in 2001 for the whole population. Multivariate survival analysis was used to assess exact survival rates in asthmatics and nonasthmatics taking relevant confounders into account. On average, the mortality rates obtained were 10.4 and 6.9 deaths 1,000 person-yrs-in asthmatics and nonasthmatics, respectively. On univariate analysis, asthma increased the relative risk (RR) of death by 1.48 (95% confidence interval (CI) 1.29-1.69). The association between asthma and death had an RR of 1.16 (95% CI 0.99-1.37) when age, sex, educational level, smoking habits, occupational exposure and forced expiratory volume in one second (FEV1) were taken into account. FEV1 was an important contributive factor causing increased risk of death in both smokers and nonsmokers. For instance, in asthmatics, the numbers of deaths due to respiratory disease and cancer appeared excessive. The present study suggests that asthmatics exhibit a higher risk of mortality.

Adult↗
PubMed2003

Air pollution: a new respiratory risk for cities in low-income countries.

Since the major accidents that occurred in the 1960s, air pollution has commonly been considered as a respiratory risk factor whose effects are most often studied in industrialised countries. Our aim is to show that it is now the turn of low- and middle-income countries to take this risk factor into account. After a discussion of the characteristics of air pollution, how it is diffused and the main known health effects (short- and long-term effects), we describe the specific differences between the cities in the North and the South. As a result of late industrialisation, cities in the South are now faced with pollution from industrial sources and urban traffic with polluting vehicles. The case of Algeria and Morocco illustrates this situation and its potential health risks. In order to prevent the health risks of air pollution in the cities of the South, systems for measuring pollution levels and epidemiological surveillance need to be put in place rapidly. This strategy can only work if it is supported by a strong partnership from industrialised countries.

Africa↗
PubMed2003

[Urban particulate air pollution: from epidemiology to health impact in public health].

Major air pollution accidents which occurred in the 1950s led to public awareness of the health hazards involved. Since that period, levels of air pollution have decreased, but several studies conducted in North America and Europe indicate that particulate air pollution is linked to increased cardiorespiratory morbidity and mortality. Despite this evidence, several questions were raised concerning the interpretation of the results (threshold effect, harvesting effect and biological plausibility). The aim of this review is to present the link between epidemiological findings and their use in health impact assessment. We review the main causal criteria applied to epidemiology in light of scientific evidence currently available. Some causality criteria are more important than others, but they all support the causal nature of the relationship between air pollution and health, and thus justify the feasibility of health impact assessment calculations. Recent studies on relative risk assessment show that even if the risk linked to worsening air quality is low, public health consequences are high. Such information must be made accessible to policy makers and the population in general so that, together with the public health workers, they can all contribute to improving air quality and health in their communities.

Adolescent↗
PubMed2001

Dyspnea and 8-year mortality among elderly men and women: the PAQUID cohort study.

PAQUID is an epidemiological cohort which aims to study cerebral and functional factors of ageing. We have examined the relationship between dyspnea level at entrance into this cohort and mortality occurring during the subsequent 8 years. Dyspnea was evaluated by a questionnaire derived from a Fletcher's five-degree scale. Mortality was recorded during follow-up according to its date and cause. Of 2762 subjects (98.9%) initially giving their dyspnea level, 935 (33.5%) had died 8 years later including 444 (40%) men and 491 (29.4%) women. Mortality was closely related to dyspnea level (p < 0.0001) both in men and women, especially for grade 3 and over, even after adjusting on age, sex, smoking history and former occupation. These results show that dyspnea grade 3 or higher is an important predictive symptom of mortality, thus suggesting that this is a threshold defining the dyspneic subject.

Aged↗
PubMed2001

Neuropsychologic effects of long-term exposure to pesticides: results from the French Phytoner study.

The Phytoner study investigated a possible association between neuropsychologic performances and long-term exposure to pesticides in Bordeaux vineyard workers, most of whom use fungicides. Among the 917 subjects interviewed from February 1997 to August 1998, 528 were directly exposed to pesticides through mixing and/or spraying (mean exposure duration: 22 years), 173 were indirectly exposed through contact with treated plants, and 216 were never exposed. All subjects performed neuropsychologic tests administered at home by trained psychologists. The risk of scoring a low performance on the tests was constantly higher in exposed subjects. When taking into account educational level, age, sex, alcohol consumption, smoking, environmental exposures, and depressive symptoms and when restricting analysis to subgroups, results remained significant for most tests, with odds ratios (OR) exceeding 2. These results point to long-term cognitive effects of low-level exposure to pesticides in occupational conditions. Given the frequency of pesticide use and the potential disabilities resulting from cognitive impairments, further toxicologic and epidemiologic research is needed to confirm these results and assess the impact on public health.

Agricultural Workers' Diseases↗