Associations of Air Pollution, Industries, and Socioeconomic Status With Acute Respiratory Distress Syndrome (ARDS) Among the Elderly in the U.S.

Abstract

In the United States, by 2030, more than 20 percent of U.S. residents are projected to be aged 65 and over, compared with 13 percent in 2010, with increased racial and ethnic diversity. Lung function declines by aging and the elderly may experience accelerated respiratory impairments followed by environmental pollution. The elderly is at high risk of developing acute respiratory distress syndrome (ARDS). ARDS is a rapidly progressive form of acute respiratory failure and is an often lethal syndrome with a mortality rate ranging from 69% to 80% among elderly patients. However, there is limited nation-wide information on association between environmental/social determinants and national ARDS incidence, particularly for vulnerable elderly population who is at high risk of ARDS. In this dissertation, we conducted a nationwide observational study to investigate the associations of long-term exposure to ambient air pollution (PM2.5 and ozone), industries construction and manufacturing sectors), and socioeconomic status (income and education) with hospital admission rates for ARDS, using Medicare data including nearly 30 million Medicare beneficiaries per year from 2000 to 2012. We estimated zip-code level associations by fitting generalized linear mixed models with log link using quasi-likelihood methods. We found that an increase of 10 construction industries per year was associated with a 0.59% increase in annual hospital admission rates for ARDS (95% CI 0.54%, 0.64%) and an increase of 10 manufacturing industries per year was associated with a 0.63% increase in annual hospital admission rates for ARDS (95% CI 0.56%, 0.71%) across all zip-codes. An increase of 1 μg/m3 in annual average PM2.5 was associated with increase in annual hospital admission rates for ARDS of 1% (0.97%, 95% CI: 0.88, 1.07). Long-term exposure to ozone pollution was not associated with ARDS. In low air pollution regions, the same annual increases in PM2.5 and ozone was associated with higher percent increase in hospital admission rates. Increased median household income and higher education in neighborhood were significantly associated with decreased hospital admission rates for ARDS. In conclusion, PM2.5 pollution, living in heavy construction and manufacturing sites, and living in poor neighborhood or area with lower educational level were risk factors for developing ARDS among the elderly residents.