Fine particulate matter and mortality: a comparison of the six cities and American Cancer Society cohorts with a medicare cohort.
BACKGROUND
The American Cancer Society study and the Harvard Six Cities study are 2 landmark cohort studies for estimating the chronic effects of fine particulate air pollution (PM2.5) on mortality. Using Medicare data, we assessed the association of PM2.5 with mortality for the same locations included in these studies.


METHODS
We estimated the chronic effects of PM2.5 on mortality for the period 2000-2002 using mortality data for cohorts of Medicare participants and average PM2.5 levels from monitors in the same counties included in the 2 studies. We estimated mortality risk associated with air pollution adjusting for individual-level (age and sex) and area-level covariates (education, income level, poverty, and employment). We controlled for potential confounding by cigarette smoking by including standardized mortality ratios for lung cancer and chronic obstructive pulmonary disease.


RESULTS
Using the Medicare data, we estimated that a 10 microg/m increase in the yearly average PM2.5 concentration is associated with 10.9% (95% confidence interval = 9.0-12.8) and with 20.8% (14.8-27.1) increases in all-cause mortality for the American Cancer Society and Harvard Six Cities study counties, respectively. The estimates are somewhat higher than those reported by the original investigators.


CONCLUSIONS
Although Medicare data lack information on some potential confounding factors, we estimated risks similar to those in the previously published reports, which incorporated more extensive information on individual-level confounders. We propose that the Medicare files can be used to construct on-going cohorts for tracking the risk of air pollution over time.
Eftim
Sorina E
SE
Department of Biostatistics, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA.
Samet
Jonathan M
JM
Janes
Holly
H
McDermott
Aidan
A
Dominici
Francesca
F
D000368:Aged; D000369:Aged, 80 and over; D000393:Air Pollutants / Q000009:adverse effects*; D000570:American Cancer Society; D015331:Cohort Studies; D015986:Confounding Factors, Epidemiologic; D004784:Environmental Monitoring; D062665:Epidemiological Monitoring; D005260:Female; D005843:Geography; D006801:Humans; D008297:Male; D006278:Medicare; D009026:Mortality; D010316:Particle Size; D052638:Particulate Matter / Q000009:adverse effects*; D012044:Regression Analysis; D014481:United States / Q000453:epidemiology
D000393:Air Pollutants; D052638:Particulate Matter