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Particulate air pollution and survival in a COPD cohort.

Zanobetti A, Bind MA, Schwartz J - Environ Health (2008)

Bottom Line: We applied Cox's proportional hazard regression model in each city, with adjustment for individual risk factors.We found significant associations in the survival analyses for single year and multiple lag exposures, with a hazard ratio for mortality for an increase of 10 microg/m(3) PM10 over the previous 4 years of 1.22 (95% CI: 1.17-1.27).These risks are significantly greater than seen in time series analyses.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA. azanobet@hsph.harvard.edu

ABSTRACT

Background: Several studies have shown cross-sectional associations between long term exposure to particulate air pollution and survival in general population or convenience cohorts. Less is known about susceptibility, or year to year changes in exposure. We investigated whether particles were associated with survival in a cohort of persons with COPD in 34 US cities, eliminating the usual cross-sectional exposure and treating PM10 as a within city time varying exposure.

Methods: Using hospital discharge data, we constructed a cohort of persons discharged alive with chronic obstructive pulmonary disease using Medicare data between 1985 and 1999. 12-month averages of PM10 were merged to the individual annual follow up in each city. We applied Cox's proportional hazard regression model in each city, with adjustment for individual risk factors.

Results: We found significant associations in the survival analyses for single year and multiple lag exposures, with a hazard ratio for mortality for an increase of 10 microg/m(3) PM10 over the previous 4 years of 1.22 (95% CI: 1.17-1.27).

Conclusion: Persons discharged alive for COPD have substantial mortality risks associated with exposure to particles. The risk is evident for exposure in the previous year, and higher in a 4 year distributed lag model. These risks are significantly greater than seen in time series analyses.

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Related in: MedlinePlus

Boxplots of the of the individually assigned 1-year PM10 mean in each city; years 1986–1999.
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Related In: Results  -  Collection

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Figure 2: Boxplots of the of the individually assigned 1-year PM10 mean in each city; years 1986–1999.

Mentions: Figure 2 presents the box-plots of the of the individually assigned 1-year PM10 mean in each city, ordered by concentration of PM10. Los Angeles has the highest concentrations level, while Honolulu the smallest. The average PM10 across all cities was 29.4 μg/m3.


Particulate air pollution and survival in a COPD cohort.

Zanobetti A, Bind MA, Schwartz J - Environ Health (2008)

Boxplots of the of the individually assigned 1-year PM10 mean in each city; years 1986–1999.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC2572050&req=5

Figure 2: Boxplots of the of the individually assigned 1-year PM10 mean in each city; years 1986–1999.
Mentions: Figure 2 presents the box-plots of the of the individually assigned 1-year PM10 mean in each city, ordered by concentration of PM10. Los Angeles has the highest concentrations level, while Honolulu the smallest. The average PM10 across all cities was 29.4 μg/m3.

Bottom Line: We applied Cox's proportional hazard regression model in each city, with adjustment for individual risk factors.We found significant associations in the survival analyses for single year and multiple lag exposures, with a hazard ratio for mortality for an increase of 10 microg/m(3) PM10 over the previous 4 years of 1.22 (95% CI: 1.17-1.27).These risks are significantly greater than seen in time series analyses.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Environmental Health, Harvard School of Public Health, Boston, MA, USA. azanobet@hsph.harvard.edu

ABSTRACT

Background: Several studies have shown cross-sectional associations between long term exposure to particulate air pollution and survival in general population or convenience cohorts. Less is known about susceptibility, or year to year changes in exposure. We investigated whether particles were associated with survival in a cohort of persons with COPD in 34 US cities, eliminating the usual cross-sectional exposure and treating PM10 as a within city time varying exposure.

Methods: Using hospital discharge data, we constructed a cohort of persons discharged alive with chronic obstructive pulmonary disease using Medicare data between 1985 and 1999. 12-month averages of PM10 were merged to the individual annual follow up in each city. We applied Cox's proportional hazard regression model in each city, with adjustment for individual risk factors.

Results: We found significant associations in the survival analyses for single year and multiple lag exposures, with a hazard ratio for mortality for an increase of 10 microg/m(3) PM10 over the previous 4 years of 1.22 (95% CI: 1.17-1.27).

Conclusion: Persons discharged alive for COPD have substantial mortality risks associated with exposure to particles. The risk is evident for exposure in the previous year, and higher in a 4 year distributed lag model. These risks are significantly greater than seen in time series analyses.

Show MeSH
Related in: MedlinePlus