The Association Between Asthma Hospitalizations and Air Pollution in Virginia, 2005
Advisor & Preceptor: Elizabeth Eustis Turf, Ph.D.
Introduction: Asthma is one of the most common
chronic diseases in the United States, with increasing prevalence over
the past twenty years. From 1980 to 2004, the estimated prevalence
of asthma in the U.S. population increased from 3.1% to 13.2%. During
2004, asthma was responsible for 497,000 hospitalizations in the U.S.;
9,460 in Virginia. Between 2004 and 2005 asthma hospitalizations
in Virginia increased by 5% to 9,955 hospitalizations; 495 additional
hospitalizations from the previous year. EPA recognizes ozone and particulate
air pollution as significant triggers for asthma symptoms in children
and adults. In Healthy People 2010, the U.S. Department
of Health and Human Services cites asthma as a major clinical and public
health concern. The reduction of environmental exposures that contribute
to events such as asthma hospitalizations is listed as one of the key
national health objectives in this national framework for disease prevention.
Even though there is evidence through clinical and epidemiological studies
that air pollution is associated with diminished lung function and asthma
exacerbations, it remains an underappreciated health threat.
Objectives: The objective of this study was
to evaluate the association between asthma hospitalizations and concentrations
of ozone and particulate matter in Virginia for 2005. This study
also looked for possible synergistic effects of multiple air pollutants
on asthma hospitalizations and at the seasonal and geographic associations.
Methods: Air pollution data for particulate
matter (PM 2.5) and ozone concentrations for 2005 were obtained from
the Virginia Department of Environmental Quality (DEQ). Hospital
discharge data for 2005 were obtained from the Virginia Health Information
(VHI) Hospital Discharge Database through the Virginia Department of
Health. All admissions with asthma as the primary
diagnosis were identified for patients who reported residing in one
of five study locations. Data were aggregated by week of admission
and location for comparison with aggregated air quality data. Data
were analyzed using SPSS and SAS. Descriptive statistics, bivariate
correlations and multiple linear regression analyses were conducted. Poisson
regression was used for the final model to adjust for a low rate of
outcome.
Results: The asthma admission rate was highest
for Henrico County, followed by Roanoke, Hampton, Madison, and Fairfax
County. A significant inverse correlation was found between
asthma admissions and ozone and and between asthma hospitalization
rates and ozone and PM2.5 levels in Henrico and Fairfax counties and
between asthma hospitalization rates and ozone in Madison county. Significant
predictive relationships were found between the asthma hospitalization
rate during the spring season in the locations of Henrico and Roanoke.
Conclusion: The findings of this exploratory ecological
analysis suggest that concentrations of PM2.5 and ozone are not useful as predictors
of asthma hospitalizations in Virginia. Future research should include
multiple years of data and use different measures of asthma morbidity to determine
whether there is a relationship between air pollution and asthma morbidity
in Virginia.
