Coarse Particulate Matter and Hospital Admissions for Cardiovascular and Respiratory Diseases Among Medicare Patients

Supplementary Data and Code

1. Code for fitting first stage regression models and combining estimates via the hierarchical model
   • CountyEstimates.R
   • PoolEstimates.R
   • 2ndStage.R
   • Regression_calibration.R
2. County-specific information [html | csv]
3. Other supplementary information [PDF]

Abstract

Context: Health risks of fine particulate matter (PM) (≤ 2.5 μm in aerodynamic diameter, PM_2.5) have been studied extensively over the last decade. Evidence concerning the health risks of the coarse fraction of PM (> 2.5 and ≤ 10 μm in aerodynamic diameter, PM_10-2.5) is limited.

Objective: To estimate risk of hospital admissions for cardiovascular (CVD) and respiratory diseases (RESP) associated with PM_10-2.5 exposure, controlling for PM_2.5. Design, Setting, and Participants: We assembled a database for 108 US counties with daily CVD and RESP admission rates, temperature and dew point temperature, and PM_10-2.5 and PM_2.5 concentrations calculated with PM monitoring data as an exposure surrogate for the study period January 1, 1999 to December 31, 2005. Admission rates were constructed from the Medicare National Claims History Files, for a study population of approximately 12 million Medicare enrollees (≥ 65) living on average 9 miles from collocated pairs of PM10 and PM_2.5 monitors.

Main Outcome Measures: Daily counts of county-wide emergency hospital admissions for CVD or RESP primary diagnoses.

Results: There were 3.7 and 1.4 million CVD and RESP admissions, respectively, during the study. A 10 μg/m³ increase in PM_10-2.5 was associated with a 0.36% (95% PI: 0.05, 0.68) increase in CVD admissions on the same day. However, when adjusted for PM_2.5, the association was no longer statistically significant (0.25%, 95% PI: -0.11 , 0.60). A 10 μg/m³ increase in PM_10-2.5 was associated with a non-statistically significant unadjusted 0.33% (95% PI: -0.21, 0.86) increase in RESP admissions and with a 0.26% (95% PI: -0.32, 0.84) increase in RESP admissions when adjusted for PM_2.5. The unadjusted associations of PM_2.5 with CVD and RESP admissions were 0.71% (95% PI: 0.45, 0.96) for same-day exposure and 0.44% (95% PI: 0.06, 0.82) for exposure 2 days before hospital admission.

Conclusion: After adjustment for PM_2.5, there were no statistically significant associations between coarse particulates and hospital admissions for cardiovascular and respiratory.

REFERENCE: Journal of the American Medical Association, Vol. 299, No. 18, pp. 2172–2179