View Abstract

A6192 - The Impact of Long-Term Exposure to PM2.5 and Ozone on the Risk of Acute Respiratory Distress Syndrome (ARDS) for the Elderly
Author Block: J. Rhee1, F. Dominici2, A. Zanobetti1, J. Schwartz3, Y. Wang2, Q. Di1, D. C. Christiani3; 1Environmental Health, T.H. Chan School of Public Health, Harvard University, Boston, MA, United States, 2Biostatistics, T.H. Chan School of Public Health, Harvard University, Boston, MA, United States, 3Environmental Health/Epidemiology, T.H. Chan School of Public Health, Harvard University, Boston, MA, United States.
RATIONALE
The incidence of ARDS is reported to be from 64.2 to 78.9 cases/100,000 person-years in the United States. There is growing scientific evidence on the impact of short or long-term exposure to various air pollutants on respiratory disease. However, there are few epidemiology studies investigating acute respiratory outcomes. Recently, Ware et al. found that chronic ozone exposure increased 1.6 times odd of developing ARDS. In our study, we aim to investigate the impact of exposure to PM2.5 and ozone on hospital admissions for ARDS using nationwide data.
METHODS
The study population is from nearly 30 million Medicare enrolees (≥65 years old) from 2000 to 2012. We used hospital admissions data of Medicare beneficiaries and ARDS occurrences are defined by the ICD-9-CM discharge diagnosis codes, where our outcome of interest was annual counts of hospital admissions for ARDS at zip code level. We computed annual average PM2.5 concentrations and average ozone concentrations during the warm season (April 1 through Sep 30) at each zip code, which were exposures of interest. We built generalized linear mixed models assuming a Poisson outcome with log link and used quasi-likelihood methods to allow for over-dispersion. Models were adjusted for the weather, race, median household income, and smoking.
RESULTS
An average of 38,127 zip codes per year were included in the study. There were a total 1,164,784 hospital admissions for ARDS from 2000 to 2012, and about two hospital admissions for ARDS within a zip code per year. Annual average PM2.5 and ozone concentrations were 11 /m3 and 39.2 ppb, respectively. We found a 6.6% (95% CI 5.1%-8.1%) increase in hospital admissions for ARDS for each 10/m3 annual increase in PM2.5 concentrations. We observed that hospital admissions for ARDS increased to 11.5% (95% CI 9.7%-13.4%), 22.4% (95% CI 20.0%-24.9%), and 34.1% (95% CI 30.9%-37.4%) by 10/m3 increase in 1-, 3-, and 5-year average PM2.5 concentrations, respectively. We also found a 2.4% (95% CI 1.4%-3.4%) increase in hospital admissions for ARDS for each 10ppb annual increase in ozone concentrations. The 1-, 3-, and 5-year average ozone exposure were associated with 3.3% (95% CI 2.2%-4.5%), 5.6% (95% CI 4.2%-7.0%), and 7.8% (95% CI 6.1%-9.5%), increase in hospital admissions for ARDS, respectively.
CONCLUSIONS
We found statistically significant associations between long-term exposure to PM2.5 and ozone concentrations and hospital admissions of ARDS among more than 30 million Medicare beneficiaries from 2000 to 2012.