Systematic review and meta-analysis of case-crossover and time-series studies of short term outdoor nitrogen dioxide exposure and ischemic heart disease morbidity
Abstract Background Nitrogen dioxide (NO2) is a pervasive urban pollutant originating primarily from vehicle emissions. Ischemic heart disease (IHD) is associated with a considerable public health burden worldwide, but whether NO2 exposure is causally related to IHD morbidity remains in question. Ou...
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BMC
2020-05-01
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Online Access: | http://link.springer.com/article/10.1186/s12940-020-00601-1 |
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author | David M. Stieb Carine Zheng Dina Salama Rania BerjawI Monica Emode Robyn Hocking Ninon Lyrette Carlyn Matz Eric Lavigne Hwashin H. Shin |
author_facet | David M. Stieb Carine Zheng Dina Salama Rania BerjawI Monica Emode Robyn Hocking Ninon Lyrette Carlyn Matz Eric Lavigne Hwashin H. Shin |
author_sort | David M. Stieb |
collection | DOAJ |
description | Abstract Background Nitrogen dioxide (NO2) is a pervasive urban pollutant originating primarily from vehicle emissions. Ischemic heart disease (IHD) is associated with a considerable public health burden worldwide, but whether NO2 exposure is causally related to IHD morbidity remains in question. Our objective was to determine whether short term exposure to outdoor NO2 is causally associated with IHD-related morbidity based on a synthesis of findings from case-crossover and time-series studies. Methods MEDLINE, Embase, CENTRAL, Global Health and Toxline databases were searched using terms developed by a librarian. Screening, data extraction and risk of bias assessment were completed independently by two reviewers. Conflicts between reviewers were resolved through consensus and/or involvement of a third reviewer. Pooling of results across studies was conducted using random effects models, heterogeneity among included studies was assessed using Cochran’s Q and I2 measures, and sources of heterogeneity were evaluated using meta-regression. Sensitivity of pooled estimates to individual studies was examined using Leave One Out analysis and publication bias was evaluated using Funnel plots, Begg’s and Egger’s tests, and trim and fill. Results Thirty-eight case-crossover studies and 48 time-series studies were included in our analysis. NO2 was significantly associated with IHD morbidity (pooled odds ratio from case-crossover studies: 1.074 95% CI 1.052–1.097; pooled relative risk from time-series studies: 1.022 95% CI 1.016–1.029 per 10 ppb). Pooled estimates for case-crossover studies from Europe and North America were significantly lower than for studies conducted elsewhere. The high degree of heterogeneity among studies was only partially accounted for in meta-regression. There was evidence of publication bias, particularly for case-crossover studies. For both case-crossover and time-series studies, pooled estimates based on multi-pollutant models were smaller than those from single pollutant models, and those based on older populations were larger than those based on younger populations, but these differences were not statistically significant. Conclusions We concluded that there is a likely causal relationship between short term NO2 exposure and IHD-related morbidity, but important uncertainties remain, particularly related to the contribution of co-pollutants or other concomitant exposures, and the lack of supporting evidence from toxicological and controlled human studies. |
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spelling | doaj.art-6b89cc880793462ab98adf2b89a7f80c2022-12-22T01:16:03ZengBMCEnvironmental Health1476-069X2020-05-0119111910.1186/s12940-020-00601-1Systematic review and meta-analysis of case-crossover and time-series studies of short term outdoor nitrogen dioxide exposure and ischemic heart disease morbidityDavid M. Stieb0Carine Zheng1Dina Salama2Rania BerjawI3Monica Emode4Robyn Hocking5Ninon Lyrette6Carlyn Matz7Eric Lavigne8Hwashin H. Shin9Environmental Health Science and Research Bureau, Health CanadaSchool of Epidemiology and Public Health, University of OttawaSchool of Epidemiology and Public Health, University of OttawaSchool of Epidemiology and Public Health, University of OttawaSchool of Population and Public Health, University of British ColumbiaLearning, Knowledge and Library Services, Health CanadaWater and Air Quality Bureau, Health, CanadaWater and Air Quality Bureau, Health, CanadaSchool of Epidemiology and Public Health, University of OttawaEnvironmental Health Science and Research Bureau, Health CanadaAbstract Background Nitrogen dioxide (NO2) is a pervasive urban pollutant originating primarily from vehicle emissions. Ischemic heart disease (IHD) is associated with a considerable public health burden worldwide, but whether NO2 exposure is causally related to IHD morbidity remains in question. Our objective was to determine whether short term exposure to outdoor NO2 is causally associated with IHD-related morbidity based on a synthesis of findings from case-crossover and time-series studies. Methods MEDLINE, Embase, CENTRAL, Global Health and Toxline databases were searched using terms developed by a librarian. Screening, data extraction and risk of bias assessment were completed independently by two reviewers. Conflicts between reviewers were resolved through consensus and/or involvement of a third reviewer. Pooling of results across studies was conducted using random effects models, heterogeneity among included studies was assessed using Cochran’s Q and I2 measures, and sources of heterogeneity were evaluated using meta-regression. Sensitivity of pooled estimates to individual studies was examined using Leave One Out analysis and publication bias was evaluated using Funnel plots, Begg’s and Egger’s tests, and trim and fill. Results Thirty-eight case-crossover studies and 48 time-series studies were included in our analysis. NO2 was significantly associated with IHD morbidity (pooled odds ratio from case-crossover studies: 1.074 95% CI 1.052–1.097; pooled relative risk from time-series studies: 1.022 95% CI 1.016–1.029 per 10 ppb). Pooled estimates for case-crossover studies from Europe and North America were significantly lower than for studies conducted elsewhere. The high degree of heterogeneity among studies was only partially accounted for in meta-regression. There was evidence of publication bias, particularly for case-crossover studies. For both case-crossover and time-series studies, pooled estimates based on multi-pollutant models were smaller than those from single pollutant models, and those based on older populations were larger than those based on younger populations, but these differences were not statistically significant. Conclusions We concluded that there is a likely causal relationship between short term NO2 exposure and IHD-related morbidity, but important uncertainties remain, particularly related to the contribution of co-pollutants or other concomitant exposures, and the lack of supporting evidence from toxicological and controlled human studies.http://link.springer.com/article/10.1186/s12940-020-00601-1Nitrogen dioxideIschemic heart diseaseTime-seriesCase-crossover |
spellingShingle | David M. Stieb Carine Zheng Dina Salama Rania BerjawI Monica Emode Robyn Hocking Ninon Lyrette Carlyn Matz Eric Lavigne Hwashin H. Shin Systematic review and meta-analysis of case-crossover and time-series studies of short term outdoor nitrogen dioxide exposure and ischemic heart disease morbidity Environmental Health Nitrogen dioxide Ischemic heart disease Time-series Case-crossover |
title | Systematic review and meta-analysis of case-crossover and time-series studies of short term outdoor nitrogen dioxide exposure and ischemic heart disease morbidity |
title_full | Systematic review and meta-analysis of case-crossover and time-series studies of short term outdoor nitrogen dioxide exposure and ischemic heart disease morbidity |
title_fullStr | Systematic review and meta-analysis of case-crossover and time-series studies of short term outdoor nitrogen dioxide exposure and ischemic heart disease morbidity |
title_full_unstemmed | Systematic review and meta-analysis of case-crossover and time-series studies of short term outdoor nitrogen dioxide exposure and ischemic heart disease morbidity |
title_short | Systematic review and meta-analysis of case-crossover and time-series studies of short term outdoor nitrogen dioxide exposure and ischemic heart disease morbidity |
title_sort | systematic review and meta analysis of case crossover and time series studies of short term outdoor nitrogen dioxide exposure and ischemic heart disease morbidity |
topic | Nitrogen dioxide Ischemic heart disease Time-series Case-crossover |
url | http://link.springer.com/article/10.1186/s12940-020-00601-1 |
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