Ambient Air Pollution and Cardiorespiratory Emergency Department Visits in Potentially Sensitive Groups

Abstract

TM6-O-09 Introduction: Limited evidence suggests that persons with comorbid conditions such as diabetes, hypertension, congestive heart failure, dysrhythmia, and respiratory illness are at increased risk of adverse cardiovascular morbidity and mortality associated with ambient air pollution. Methods: We collected information on over 10 million emergency department visits from 41 hospitals from 1993 through 2004. Visits for several cardiovascular disease subgroups were examined in relation to daily levels of ambient pollutants using a case-crossover framework. Heterogeneity of the pollution risk estimates was examined for the following comorbid conditions, identified using secondary diagnostic codes from billing records: diabetes, hypertension, congestive heart failure (CHF), dysrhythmia, atherosclerosis, chronic obstructive pulmonary disease (COPD), upper respiratory infections, pneumonia, and asthma. Results: In preliminary analyses using visits from 1993 through 2000, we observed stronger associations of air pollution with cardiac dysrhythmia visits among patients with comorbid hypertension and diabetes than among patients without these comborbid conditions (eg, for nitrogen dioxide: odds ratio [OR] per 20-ppb increase: 1.144; 95% CI, 1.036–1.262 among visits with comorbid diabetes vs. OR per 20-ppb increase: 1.012; 95% CI, 0.987–1.038 among visits without comorbid diabetes; P value assessing heterogeneity of the pollution estimates: 0.019). Similar evidence of effect modification was observed for peripheral and cerebrovascular disease and CHF visits by comorbid COPD. Evidence of effect modification by comorbid diabetes and hypertension was primarily observed in relation to particulate matter (PM10), nitrogen dioxide, and carbon monoxide, while evidence of effect modification by comorbid COPD was also observed in response to ozone. Results for the expanded time period, as well as results for speciated particle data, will be presented. Discussion: These findings provide further evidence of increased susceptibility to adverse cardiovascular events associated with ambient air pollution among persons with comorbid hypertension, diabetes, and COPD.