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Survival Analysis to Estimate Association between Short-Term Mortality and Air Pollution

BACKGROUND: Ecologic studies are commonly used to report associations between short-term air pollution and mortality. In such studies, the unit of observation is the day rather than the individual. Moreover, individual data on the subjects are rarely available, which limits the assessment of individ...

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Autores principales: Lepeule, Johanna, Rondeau, Virginie, Filleul, Laurent, Dartigues, Jean-Francois
Formato: Texto
Lenguaje:English
Publicado: National Institute of Environmental Health Sciences 2006
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1367838/
https://www.ncbi.nlm.nih.gov/pubmed/16451861
http://dx.doi.org/10.1289/ehp.8311
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author Lepeule, Johanna
Rondeau, Virginie
Filleul, Laurent
Dartigues, Jean-Francois
author_facet Lepeule, Johanna
Rondeau, Virginie
Filleul, Laurent
Dartigues, Jean-Francois
author_sort Lepeule, Johanna
collection PubMed
description BACKGROUND: Ecologic studies are commonly used to report associations between short-term air pollution and mortality. In such studies, the unit of observation is the day rather than the individual. Moreover, individual data on the subjects are rarely available, which limits the assessment of individual risk factors. These associations can also be investigated using case–crossover studies. However, by definition, individual risk factors are not studied, and such studies analyze only dead subjects, which limits the statistical power. OBJECTIVE: We suggest that the survival analysis is more suitable when cohorts are examined with a time-dependent ecologic exposure. To our knowledge, to date this type of analysis has never been proposed. DESIGN, PARTICIPANTS, MEASUREMENTS: In the present study we used a Cox proportional hazards model to investigate the distribution over time of the short-term effect of black smoke and sulfur dioxide in 439 nonaccidental and 158 cardiorespiratory deaths among the 1,469 subjects of the Personnes Agées QUID (PAQUID) cohort in Bordeaux, France. The model has a delayed entry and a polynomial distributed lag from 0 to 5 days. Results are adjusted for individual risk factors, temperature, relative humidity, weekday, season, influenza epidemics, and a time function to control temporal trends. RESULTS: We identified a positive and significant association between cardiorespiratory mortality and black smoke, with a 24% increase in deaths 3 days after a 10-μg/m(3) increase in black smoke (95% confidence interval, 4–47%). CONCLUSIONS: We conclude that the Cox proportional hazards model with time-dependent covariates is very suitable to investigate simultaneously the short-term effect of air pollution on health and the effect of individual risk factors on a cohort study.
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spelling pubmed-13678382006-02-22 Survival Analysis to Estimate Association between Short-Term Mortality and Air Pollution Lepeule, Johanna Rondeau, Virginie Filleul, Laurent Dartigues, Jean-Francois Environ Health Perspect Research BACKGROUND: Ecologic studies are commonly used to report associations between short-term air pollution and mortality. In such studies, the unit of observation is the day rather than the individual. Moreover, individual data on the subjects are rarely available, which limits the assessment of individual risk factors. These associations can also be investigated using case–crossover studies. However, by definition, individual risk factors are not studied, and such studies analyze only dead subjects, which limits the statistical power. OBJECTIVE: We suggest that the survival analysis is more suitable when cohorts are examined with a time-dependent ecologic exposure. To our knowledge, to date this type of analysis has never been proposed. DESIGN, PARTICIPANTS, MEASUREMENTS: In the present study we used a Cox proportional hazards model to investigate the distribution over time of the short-term effect of black smoke and sulfur dioxide in 439 nonaccidental and 158 cardiorespiratory deaths among the 1,469 subjects of the Personnes Agées QUID (PAQUID) cohort in Bordeaux, France. The model has a delayed entry and a polynomial distributed lag from 0 to 5 days. Results are adjusted for individual risk factors, temperature, relative humidity, weekday, season, influenza epidemics, and a time function to control temporal trends. RESULTS: We identified a positive and significant association between cardiorespiratory mortality and black smoke, with a 24% increase in deaths 3 days after a 10-μg/m(3) increase in black smoke (95% confidence interval, 4–47%). CONCLUSIONS: We conclude that the Cox proportional hazards model with time-dependent covariates is very suitable to investigate simultaneously the short-term effect of air pollution on health and the effect of individual risk factors on a cohort study. National Institute of Environmental Health Sciences 2006-02 2005-10-03 /pmc/articles/PMC1367838/ /pubmed/16451861 http://dx.doi.org/10.1289/ehp.8311 Text en http://creativecommons.org/publicdomain/mark/1.0/ Publication of EHP lies in the public domain and is therefore without copyright. All text from EHP may be reprinted freely. Use of materials published in EHP should be acknowledged (for example, ?Reproduced with permission from Environmental Health Perspectives?); pertinent reference information should be provided for the article from which the material was reproduced. Articles from EHP, especially the News section, may contain photographs or illustrations copyrighted by other commercial organizations or individuals that may not be used without obtaining prior approval from the holder of the copyright.
spellingShingle Research
Lepeule, Johanna
Rondeau, Virginie
Filleul, Laurent
Dartigues, Jean-Francois
Survival Analysis to Estimate Association between Short-Term Mortality and Air Pollution
title Survival Analysis to Estimate Association between Short-Term Mortality and Air Pollution
title_full Survival Analysis to Estimate Association between Short-Term Mortality and Air Pollution
title_fullStr Survival Analysis to Estimate Association between Short-Term Mortality and Air Pollution
title_full_unstemmed Survival Analysis to Estimate Association between Short-Term Mortality and Air Pollution
title_short Survival Analysis to Estimate Association between Short-Term Mortality and Air Pollution
title_sort survival analysis to estimate association between short-term mortality and air pollution
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1367838/
https://www.ncbi.nlm.nih.gov/pubmed/16451861
http://dx.doi.org/10.1289/ehp.8311
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