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Daily diaries of respiratory symptoms and air pollution: methodological issues and results.

Daily diaries of respiratory symptoms are a powerful technique for detecting acute effects of air pollution exposure. While conceptually simple, these diary studies can be difficult to analyze. The daily symptom rates are highly correlated, even after adjustment for covariates, and this lack of inde...

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Detalles Bibliográficos
Autores principales: Schwartz, J, Wypij, D, Dockery, D, Ware, J, Zeger, S, Spengler, J, Ferris, B
Formato: Texto
Lenguaje:English
Publicado: 1991
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1519478/
https://www.ncbi.nlm.nih.gov/pubmed/2050059
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author Schwartz, J
Wypij, D
Dockery, D
Ware, J
Zeger, S
Spengler, J
Ferris, B
author_facet Schwartz, J
Wypij, D
Dockery, D
Ware, J
Zeger, S
Spengler, J
Ferris, B
author_sort Schwartz, J
collection PubMed
description Daily diaries of respiratory symptoms are a powerful technique for detecting acute effects of air pollution exposure. While conceptually simple, these diary studies can be difficult to analyze. The daily symptom rates are highly correlated, even after adjustment for covariates, and this lack of independence must be considered in the analysis. Possible approaches include the use of incidence instead of prevalence rates and autoregressive models. Heterogeneity among subjects also induces dependencies in the data. These can be addressed by stratification and by two-stage models such as those developed by Korn and Whittemore. These approaches have been applied to two data sets: a cohort of school children participating in the Harvard Six Cities Study and a cohort of student nurses in Los Angeles. Both data sets provide evidence of autocorrelation and heterogeneity. Controlling for autocorrelation corrects the precision estimates, and because diary data are usually positively autocorrelated, this leads to larger variance estimates. Controlling for heterogeneity among subjects appears to increase the effect sizes for air pollution exposure. Preliminary results indicate associations between sulfur dioxide and cough incidence in children and between nitrogen dioxide and phlegm incidence in student nurses.
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spelling pubmed-15194782006-07-26 Daily diaries of respiratory symptoms and air pollution: methodological issues and results. Schwartz, J Wypij, D Dockery, D Ware, J Zeger, S Spengler, J Ferris, B Environ Health Perspect Research Article Daily diaries of respiratory symptoms are a powerful technique for detecting acute effects of air pollution exposure. While conceptually simple, these diary studies can be difficult to analyze. The daily symptom rates are highly correlated, even after adjustment for covariates, and this lack of independence must be considered in the analysis. Possible approaches include the use of incidence instead of prevalence rates and autoregressive models. Heterogeneity among subjects also induces dependencies in the data. These can be addressed by stratification and by two-stage models such as those developed by Korn and Whittemore. These approaches have been applied to two data sets: a cohort of school children participating in the Harvard Six Cities Study and a cohort of student nurses in Los Angeles. Both data sets provide evidence of autocorrelation and heterogeneity. Controlling for autocorrelation corrects the precision estimates, and because diary data are usually positively autocorrelated, this leads to larger variance estimates. Controlling for heterogeneity among subjects appears to increase the effect sizes for air pollution exposure. Preliminary results indicate associations between sulfur dioxide and cough incidence in children and between nitrogen dioxide and phlegm incidence in student nurses. 1991-01 /pmc/articles/PMC1519478/ /pubmed/2050059 Text en
spellingShingle Research Article
Schwartz, J
Wypij, D
Dockery, D
Ware, J
Zeger, S
Spengler, J
Ferris, B
Daily diaries of respiratory symptoms and air pollution: methodological issues and results.
title Daily diaries of respiratory symptoms and air pollution: methodological issues and results.
title_full Daily diaries of respiratory symptoms and air pollution: methodological issues and results.
title_fullStr Daily diaries of respiratory symptoms and air pollution: methodological issues and results.
title_full_unstemmed Daily diaries of respiratory symptoms and air pollution: methodological issues and results.
title_short Daily diaries of respiratory symptoms and air pollution: methodological issues and results.
title_sort daily diaries of respiratory symptoms and air pollution: methodological issues and results.
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1519478/
https://www.ncbi.nlm.nih.gov/pubmed/2050059
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