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PARTICULATE MATTER (PM) AND HOSPITAL ADMISSIONS AMONG U.S. VETERANS
Impact/Purpose:
This work will help to define the conditions of susceptibility to the respiratory effects of inhaled PM in a human population.
Description:
Epidemiological studies have consistently demonstrated that exposure to particulate matter (PM) can result in increased mortality and morbidity. The susceptible population, the nature of morbidity and cause of death, however, have not been clearly identified. To accomplish these objectives, large-scale epidemiological studies that correlate inpatient information with PM data will be required. A major limiting factor for such studies is the difficulty in collecting pertinent information from a very large number of patients. We have recently found that the Veteran's Administration's (VA) Health System contains detailed inpatient information in a nationwide inpatient database that is accessible via their Medical Centers. The patient information includes demographics, health profile, admission date, and diagnosis for all veterans admitted to VA Medical Centers in the U.S. In May 2001, we presented a poster on the association of PM and co-pollutants with daily admissions to the Denver VA Medical Center. The poster was well received and these results will form the basis for our first scientific publication. We examined 17,933 admissions to the Denver VA Medical Center over a six-year period (1994-1999) after restricting to male residents of Colorado. Of these admissions, 1,187 had a primary respiratory diagnosis (ICD9 460-519), 2,610 had one or more secondary respiratory diagnoses and 309 had both primary and secondary respiratory diagnoses. Environmental data was obtained from EPA's Aerometric Information Retrieval System (AIRS) and meteorological data was obtained from the National Weather Service. Among the 2,610 admissions with underlying respiratory disease, a 15 mg/m3 increment in the two-day moving average of particular matter less than 10 microns (PM10) was associated with a 40 percent increase in the rate of respiratory admissions (95% CI 12.3% to 74.8%) after adjustment for trend, season, day of week, temperature, relative humidity, and precipitation. The association among all admissions with a primary respiratory diagnosis regardless of secondary conditions (n = 1,187) was much less (+2.2%, 95% CI -10.1% to 16.3%). Thus, subjects with underlying respiratory disease appear to be at increased risk of respiratory admissions related to exposures to ambient particulate matter.