The Sixteenth Conference of the International Society for Environmental Epidemiology (ISEE): Abstracts
The effects of ambient air pollution on acute morbidity and mortality have been studied extensively for the past decades. Some studies have indicated that certain subgroups, such as persons with existing cardiovascular or respiratory disease, are more likely to be affected by air pollution. In the present study, survivors of an acute myocardial infarction (AMI), a potentially sensitive subgroup, were followed with respect to daily all-cause mortality in relation to short-term exposure to ambient particulate and gaseous air pollution.
In this European multi-center study of five cities, acute myocardial infarction survivors in the period 1992–2000 were recruited via regional administrative hospital discharge registers (3 centers, no upper age limit on data) or AMI registries (2 centers, upper age limits at 75 and 79). Daily all-cause mortality in these cohorts was followed for 3–7 years. Daily air pollution levels were acquired from central monitor sites and particle number concentrations (PNC) were retrospectively estimated based on meteorology and concentrations of measured pollutants and interactions between the two. City specific time series analyses with Poisson regression were conducted adjusting for season, meteorology and calendar effects. Results were pooled using fixed effects models when city-specific estimates were homogeneous; otherwise random effects models were used.
Pooled results of all five cities are shown below.
The table illustrates that no statistically significant associations between total mortality and levels of the studied pollutants were observed for the short lags. In the two centers relying on AMI register data, mortality and ambient particles showed RR=1.075, (95% CI: 1.005–1.151) for PM10 lag 0–1, and RR=1.071, (95% CI: 1.024–1.119) for PNC of the same lag. Carbon monoxide (CO) was also shown to be associated with acute mortality in these two centers, RR=1.057, (95% CI: 1.001–1.116) for the same lag. Longer averaging times showed more consistent positive effects.
The results of the present study suggest that short-term exposure to air pollution is associated with all-cause mortality in AMI survivors, with a considerable heterogeneity between cities and stronger positive effects for long lags. Differences in demographic structure between centers might explain some of the heterogeneity of the results, but further exploration is needed.