The Effect of Fine Particulate Air Matter on Emergency Admissions For Copd and Pneumonia: a Multi-City Case-Crossover Analysis

Abstract

P-078 Introduction: While many studies have examined the effects of air pollution on mortality, fewer studies have examined hospital admissions for pneumonia and COPD, and generally in smaller multi-city or single city studies. In addition, PM2.5 data has only recently been available. Method: We conducted a multi-city case-crossover study of the acute effect of PM2.5 on the increased risk of being admitted to the hospital among the elderly in thirty-nine US cities with 451,000 admissions for pneumonia and 234,000 admissions for chronic obstructive pulmonary disease (COPD). We examined the association between daily fine particulate air matter (PM2.5) and Medicare data (age ge 65) on hospital admissions from the emergency room with a primary diagnosis of COPD (ICD-9: 490–496, except 493) and pneumonia (ICD-9: 480–487), in those cities for the years 1999–2003. In the first stage of the analysis, we applied a case-crossover design in each city with referent exposure days chosen using the time-stratified approach, with control days matched on year, month, and temperature to control possible residual confounding by weather. In the second stage of the analysis we combined the city-specific estimates using a random effect approach. Results: For COPD we found the higher effect at lag 1 with an increase of 1.17% (95% CI: 0.3%, 2.0%) for a 10 μg/m3 increase in PM2.5. We found a 1.51% increase (95% CI: 0.5%, 2.6%) in risk of admissions for pneumonia and PM2.5 two days before. Matching on every third day yielded similar results. Discussion and Conclusion: We conclude that our analysis showed an increased risk of hospitalization for COPD and pneumonia associated with PM2.5 among the elderly. More studies are needed to understand the biological mechanism and to examine effect modification.