Association entre pollution atmosphérique et infarctus du myocarde sur base de la méthode cas-croisé

Short-term effects of nitrogen dioxide on hospital admissions for cardiovascular disease in Wallonia, Belgium

Many studies have shown a short-term association between NO₂ and cardiovascular disease. However, few data are available on the delay between exposure and a health-related event. The aim of the present study is to determine the strength of association between NO₂ and cardiovascular health in Wallonia for the period 2008-2011. This study also seeks to evaluate the effects of age, gender, season and temperature on this association. The effect of the delay between exposure and health-related event was also investigated. The daily numbers of hospital admissions for arrhythmia, acute myocardial infarction, ischemic and haemorrhagic stroke were taken from a register kept by Belgian hospitals. Analyses were performed using the quasi-Poisson regression model adjusted for seasonality, long-term trend, day of the week, and temperature. Our study confirms the existence of an association between NO₂ and cardiovascular disease. Apart from haemorrhagic stroke, the strongest association between NO₂ concentrations and number of hospital admissions is observed at lag 0. For haemorrhagic stroke, the association is strongest with a delay of 2days. All associations calculated without stratification are statistically significant and range from an excess relative risk of 2.8% for myocardial infarction to 4.9% for haemorrhagic strokes. The results of this study reinforce the evidence of the short-term effects of NO₂ on hospital admissions for cardiovascular disease. The different delay between exposure and health-related event for haemorrhagic stroke compared to ischemic stroke suggests different mechanisms of action.

Seasonal Effect on Association between Atmospheric Pollutants and Hospital Emergency Room Visit for Stroke

BACKGROUND

The relationship between air pollution and stroke is conflicting. This study was conducted to document the relationship between daily changes in atmospheric pollutants and hospital emergency room visits (ERVs) for stroke.

METHODS

Data of daily hospital ERVs for stroke and atmospheric pollutants in Changsha city between 2008 and 2009 were collected. Using a time-stratified bidirectional case-crossover design, we analyzed the association between atmospheric pollutants and stroke incidence in 4 seasons.

RESULTS

In the single-pollutant model, we found changes in sulfur dioxide (SO₂), nitrogen dioxide (NO₂), and particulate matters (PM₁₀) were significantly associated with cerebral hemorrhage and cerebral infarction (P < .05) in lags of 0-2 days in autumn. A 10-µg/m³ increase in SO₂ in autumn was significantly associated with ERVs for both cerebral hemorrhage (odds ratio [OR], 1.166; 95% confidence interval [CI], 1.012-1.343) and cerebral infarction (OR, 1.214; 95% CI, 1.018-1.448). NO₂ in autumn was significantly associated with ERVs for cerebral hemorrhage and infarction with OR = 1.162 (95% CI, 1.005-1.344) and OR = 1.137 (95% CI, 1.011-1.279), respectively. PM₁₀ in autumn was significantly associated with ERVs for cerebral hemorrhage and infarction with OR = 1.147 (95% CI, 1.045-1.259) and OR = 1.091 (95% CI, 1.019-1.168), respectively. Results of the multipollutant model showed that in autumn after PM₁₀ and NO₂ adjustment, only a 10-µg/m³ increase in SO₂ was significantly associated with ERVs for cerebral infarction (OR, 1.158; 95% CI, 1.006-1.333; P < .05). SO₂, NO₂, and PM₁₀ were not associated with ERVs for cerebral hemorrhage (P > .05).

CONCLUSIONS

This study demonstrates that the change in atmospheric SO₂ levels in Changsha is significantly associated with the stroke incidence in autumn.

Short-term effects of air pollution on hospitalization for acute myocardial infarction: age effect on lag pattern

The aim of the present study is to analyse the age effect on the lag patterns of relative risk of hospitalization for acute myocardial infarction and NO₂, PM₁₀ and O₃. Daily hospitalizations for AMI during the period 2008-2011 were extracted from administrative data. Analyses were performed using the quasi-Poisson regression model adjusted for seasonality, long-term trend, day of the week and temperature. We observed very different patterns depending on age. For NO₂ and PM₁₀, the younger group (25-54 years) shows a more delayed effect in comparison with the two older age groups (55-64 and ≥ 65 years). Overall, the associations between NO₂ and AMI are higher compared to PM₁₀. There are no associations between O₃ and AMI. This study indicates that age plays a major role in the lag pattern. Younger people have delayed effects, but they are nevertheless sensitive to air pollution.