[Estimating emergency hospital admissions to gauge short-term effects of air pollution: evaluation of health data quality]. / Estimation des hospitalisations en urgence pour mesurer les effets à court terme de la pollution atmosphérique : qualité des données issues du PMSI.

The study of the short-term effects and health impact of air pollution is carrier out by the ERPURS regional surveillance program which utilizes hospitalization data obtained from the French hospital information system (PMSI) to determine these links. This system does not permit the distinction between emergency hospital admissions from scheduled ones, which cannot be related to short term changes in air pollution levels. This study examines how scheduled admissions affect the quality of the health indicators used to estimate air pollution effects. This indicator is compared to three new emergency hospitalisation indicators reconstructed based on data from the public hospitals in Paris, partly from the PMSI data and partly with data from an on-line emergency network that regroups all of the computerized emergency services. According to the pathology, scheduled admissions present a difficulty which affects the capacity to highlight the weakest risks with any precision.

Short term effects of air pollution on hospitalizations for cardiovascular diseases in eight French cities: the PSAS program.

INTRODUCTION: Short term associations between air pollution indicators and hospitalizations for cardiovascular diseases have been suggested by epidemiological and clinical studies. The present study aims at estimating the association between particles with diameter <10 microm (PM(10)), nitrogen dioxide (NO(2)) and ozone and hospitalizations for cardiovascular diseases in eight French cities during the 1998-2003 period. METHODS: The daily number of hospitalizations in each city was extracted from the French hospital information system (PMSI) for cardiovascular diseases, cardiac diseases, ischemic heart diseases and stroke. Excess relative risks (ERRs) of hospitalization associated with a 10 microg/m(3) increase in pollutant levels were estimated in each city by fitting a Poisson regression model, controlling for well-known confounding factors and temporal trends. City-specific results were then combined by inverse variance weighting. RESULTS: Daily number of hospitalizations for cardiovascular diseases was associated with PM(10) levels (for a 10 microg/m(3) increase, ERR=0.8%, 95% CI: [0.2, 1.5]), with NO(2) (1.1%, [0.6, 1.6]) but not with ozone (0.1% [-0.2%, 0.5%]). Associations were stronger in people aged 65 years and over, and when only hospitalizations for ischemic heart diseases were considered. No association was found between strokes and air pollution levels. DISCUSSION: Our study suggests that the ambient levels of air pollutants currently experienced in the eight French cities, which are close to European air quality guidelines, are yet linked to a short term increase of hospitalizations for cardiovascular diseases. These results are consistent with epidemiological and toxicological data on the cardiovascular effects of air pollution.

Air pollution and doctors' house calls for respiratory diseases in the Greater Paris area (2000-3).

This study describes the short-term relationships between the daily levels of PM10, PM2.5, NO2 and the number of doctors' house calls for asthma, upper respiratory diseases (URD) and lower respiratory diseases (LRD) in Greater Paris for the years 2000-3. Doctors' house calls are a relevant health indicator for the study of short-term health effects of air pollution. Indeed, it is potentially more sensitive than indicators such as general hospital admissions due to the severity of diseases motivating the call. In this study, time-series analysis was used. The daily numbers of doctor's house calls were adjusted for time trends, seasonal factors, day of the week, influenza, weather and pollen. Up to 15 days of lag between exposure and health effects was considered using distributed lag models. A total of about 1,760,000 doctors' house calls for all causes occurred during the study period, among which 8027 were for asthma, 52,928 for LRD and 74,845 for URD. No significant increase in risk was found between air pollution and doctors' house calls for asthma. No significant association was found between NO2 and doctors' house calls. An increase of 10 microg/m3 in the mean levels of PM10 and PM2.5 encountered during the 3 previous days was associated with an increase of 3% (0.8% and 5.3%) and 5.9% (2.9% and 9.0%) in the number of doctor's house calls for URD and LRD, respectively. Considering up to 15 days between exposure and health outcomes, effects persist until 4 days after exposure and then decrease progressively. No morbidity displacement was observed. This study shows a significant heath effect of ambient particles (PM2.5 and PM10). When compared to the RRs obtained for mortality or hospital admissions in the same area, the values of the RRs obtained in this study confirm the higher sensibility of doctor's house calls for respiratory diseases as a health indicator.

The relation between temperature, ozone, and mortality in nine French cities during the heat wave of 2003.

BACKGROUND: During August 2003, record high temperatures were observed across Europe, and France was the country most affected. During this period, elevated ozone concentrations were measured all over the country. Questions were raised concerning the contribution of O3 to the health impact of the summer 2003 heat wave. METHODS: We used a time-series design to analyze short-term effects of temperature and O3 pollution on mortality. Counts of deaths were regressed on temperatures and O3 levels, controlling for possible confounders: long-term trends, season, influenza outbreaks, day of the week, and bank holiday effects. For comparison with previous results of the nine cities, we calculated pooled excess risk using a random effect approach and an empirical Bayes approach. FINDINGS: For the nine cities, the excess risk of death is significant (1.01% ; 95% confidence interval, 0.58-1.44) for an increase of 10 microg/m3 in O3 level. For the 3-17 August 2003 period, the excess risk of deaths linked to O3 and temperatures together ranged from 10.6% in Le Havre to 174.7% in Paris. When we compared the relative contributions of O3 and temperature to this joint excess risk, the contribution of O3 varied according to the city, ranging from 2.5% in Bordeaux to 85.3% in Toulouse. INTERPRETATION: We observed heterogeneity among the nine cities not only for the joint effect of O3 and temperatures, but also for the relative contribution of each factor. These results confirmed that in urban areas O3 levels have a non-negligible impact in terms of public health.

Impact of the 2003 heatwave on all-cause mortality in 9 French cities.

BACKGROUND: A heatwave occurred in France in August 2003, with an accompanying excess of all-cause mortality. This study quantifies this excess mortality and investigates a possible harvesting effect in the few weeks after the heatwave. METHODS: A time-series study using a Poisson regression model with regression splines to control for nonlinear confounders was used to analyze the correlation between heatwave variable and mortality in 9 French cities. RESULTS: After controlling for long-term and seasonal time trends and the usual effects of temperature and air pollution, we estimated that 3,096 extra deaths resulted from the heatwave. The maximum daily relative risk of mortality during the heatwave (compared with expected deaths at that time of year) ranged from 1.16 in Le Havre to 5.00 in Paris. There was little evidence of mortality displacement in the few weeks after the heatwave, with an estimated deficit of 253 deaths at the end of the period. CONCLUSIONS: The heatwave in France during August 2003 was associated with a large increase in the number of deaths. The impact estimated using a time-series design was consistent with crude previous estimates of the impact of the heatwave. This finding suggests that neither air pollution nor long-term and seasonal trends confounded previous estimates. There was no evidence to suggest that the extras deaths associated with the heatwave were simply brought forward in time.