Medicare Cohort Air Pollution Study (MCAPS), 1999–2002

Supplementary Materials

FREQUENTLY ASKED QUESTIONS about the MCAPS study

Press release from The Johns Hopkins Bloomberg School of Public Health

Information about the counties used in the study. More information about the counties in MCAPS is also available on our Google map

Background information particulate matter from the EPA:

• Particle Pollution in 2003
• Summary of Counties Violating the PM_2.5 Primary Standards

Materials for Reproducing Study Results

County-specific estimates

Below are tables containing county-specific estimates of the assocation between PM_2.5 and hospital admissions for various outcomes. The estimates here are the raw regression coefficients (beta) and variances (var) taken from the models described in the paper. NOTE: The HTML tables are large and may take a long time to load into your browser.

• Subset of models used for Table 1: HTML | Comma separated value (CSV) [194K]
• All models, used for Figure 2: HTML | Comma separated value (CSV) [1.8M]

Comma separated value (CSV) files are better suited for reading into statistical analysis programs.

Please note that the principal findings of the study are estimates of the national and regional effects of short-term exposure to PM_2.5. County-specific estimates are provided solely for the purpose of reproducing those findings.

Code for combining estimates

All of the data analysis was conducted with the R statistical analysis package.

• RunTLNISE.R --- combines city specific estimates together to produce a national average estimate. The files fips.include.rda and estimates-full.csv are needed to run this code.
• MakePlot_Table.R --- creates Figure 2 and Table 3 containing national average estimates for PM_2.5 and hospital admissions.

Stage 1 model fitting code

• runModels.R --- Stage 1 data analysis pipeline; fitting county-specific Poisson regression models.
• modeling.R --- functions for fitting single county models.
• outcomeNames.R --- vector of names of different outcomes.
• siteList.R --- vector of FIPS codes for the sites used.

All code files are distributed under the terms of the GNU General Public License.

Air Pollution and Weather Data

The PM_2.5, temperature, and dew point temperature data used for this study are available in comma separated value (CSV) files, one for each county. Counties are identified by their 5-digit FIPS codes.

• Download air pollution and weather data: Goto directory

Abstract

Context: Evidence on the health risks associated with short-term exposure to fine particles (particulate matter less than 2.5 μm in aerodynamic diameter [PM_2.5]) is limited. Results from a recent new national monitoring network for make possible systematic research on health risks at national and regional scales.

Objective: To estimate risk of cardiovascular and respiratory hospital admissions associated with short-term exposure to PM_2.5 for Medicare enrollees and to explore heterogeneity of the variation of risks across regions.

Design, Setting, and Participants: A national database comprising daily time-series data daily for 1999 through 2002 on hospital admission rates (constructed from the Medicare National Claims History Files) for cardiovascular and respiratory outcomes and injuries, ambient PM_2.5 levels, and temperature and dew point temperature for 204 US urban counties (population >200,000) with 11.5 million Medicare enrollees (aged >65 years) living an average of 5.9 miles from a PM_2.5 monitor.

Main Outcome Measures: Daily counts of county-wide hospital admissions for primary diagnosis of cerebrovascular, peripheral, and ischemic heart diseases, heart rhythm, heart failure, chronic obstructive pulmonary disease, and respiratory infection, and injuries as a control outcome.

Results: There was a short-term increase in hospital admission rates associated with PM_2.5 for all of the health outcomes except injuries. The largest association was for heart failure, which has a 1.28% (95% confidence interval, 0.78%--1.78%) increase in risk per 10 μg/m³ increase in same-day PM_2.5. Cardiovascular risks tended to be higher in counties located in the Eastern region of the United States, which included the Northeast, the Southeast, the Midwest, and the South.

Conclusion: Short-term exposure to PM_2.5 increases the risk for hospital admission for cardiovascular and respiratory diseases.

REFERENCE: Journal of the American Medical Association, Vol. 295, No. 10, pp. 1127–1134.