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Ozone and childhood respiratory disease in three US cities: evaluation of effect measure modification by neighborhood socioeconomic status using a Bayesian hierarchical approach

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ABSTRACT

Background: Ground-level ozone is a potent airway irritant and a determinant of respiratory morbidity. Susceptibility to the health effects of ambient ozone may be influenced by both intrinsic and extrinsic factors, such as neighborhood socioeconomic status (SES). Questions remain regarding the manner and extent that factors such as SES influence ozone-related health effects, particularly across different study areas.

Methods: Using a 2-stage modeling approach we evaluated neighborhood SES as a modifier of ozone-related pediatric respiratory morbidity in Atlanta, Dallas, & St. Louis. We acquired multi-year data on emergency department (ED) visits among 5–18 year olds with a primary diagnosis of respiratory disease in each city. Daily concentrations of 8-h maximum ambient ozone were estimated for all ZIP Code Tabulation Areas (ZCTA) in each city by fusing observed concentration data from available network monitors with simulations from an emissions-based chemical transport model. In the first stage, we used conditional logistic regression to estimate ZCTA-specific odds ratios (OR) between ozone and respiratory ED visits, controlling for temporal trends and meteorology. In the second stage, we combined ZCTA-level estimates in a Bayesian hierarchical model to assess overall associations and effect modification by neighborhood SES considering categorical and continuous SES indicators (e.g., ZCTA-specific levels of poverty). We estimated ORs and 95% posterior intervals (PI) for a 25 ppb increase in ozone.

Results: The hierarchical model combined effect estimates from 179 ZCTAs in Atlanta, 205 ZCTAs in Dallas, and 151 ZCTAs in St. Louis. The strongest overall association of ozone and pediatric respiratory disease was in Atlanta (OR = 1.08, 95% PI: 1.06, 1.11), followed by Dallas (OR = 1.04, 95% PI: 1.01, 1.07) and St. Louis (OR = 1.03, 95% PI: 0.99, 1.07). Patterns of association across levels of neighborhood SES in each city suggested stronger ORs in low compared to high SES areas, with some evidence of non-linear effect modification.

Conclusions: Results suggest that ozone is associated with pediatric respiratory morbidity in multiple US cities; neighborhood SES may modify this association in a non-linear manner. In each city, children living in low SES environments appear to be especially vulnerable given positive ORs and high underlying rates of respiratory morbidity.

Electronic supplementary material: The online version of this article (doi:10.1186/s12940-017-0244-2) contains supplementary material, which is available to authorized users.

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Effect modification by categorical indicators of neighborhood SES using combined and city-specific models. a: association between ozone and pediatric respiratory ED visits in undereducated areas (low SES) and non-undereducated areas (high SES). b: association between ozone and pediatric respiratory ED visits in poverty areas (low SES) and non-poverty areas (high SES). c: association between ozone and pediatric respiratory ED visits in areas above the 90th percentile of the NDI (low SES) and in areas below the 90th percentile (higher SES). Odds ratios and 95% posterior intervals per 25 ppb ozone are presented. Black points and error bars represent ORs and 95% PIs in low SES areas; gray points and bars represent ORs and 95% PIs in areas of higher SES. Undereducated areas: ≥ 25% the adult population (≥25 years old) with less than a 12th grade education. Poverty area: ≥ 20% households living below the Federal Poverty Line. Abbreviations: ED, Emergency Department; NDI, Neighborhood Deprivation Index; SES, socioeconomic status; ZCTA, Zip Code Tabulation Area
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Fig2: Effect modification by categorical indicators of neighborhood SES using combined and city-specific models. a: association between ozone and pediatric respiratory ED visits in undereducated areas (low SES) and non-undereducated areas (high SES). b: association between ozone and pediatric respiratory ED visits in poverty areas (low SES) and non-poverty areas (high SES). c: association between ozone and pediatric respiratory ED visits in areas above the 90th percentile of the NDI (low SES) and in areas below the 90th percentile (higher SES). Odds ratios and 95% posterior intervals per 25 ppb ozone are presented. Black points and error bars represent ORs and 95% PIs in low SES areas; gray points and bars represent ORs and 95% PIs in areas of higher SES. Undereducated areas: ≥ 25% the adult population (≥25 years old) with less than a 12th grade education. Poverty area: ≥ 20% households living below the Federal Poverty Line. Abbreviations: ED, Emergency Department; NDI, Neighborhood Deprivation Index; SES, socioeconomic status; ZCTA, Zip Code Tabulation Area

Mentions: Categorical ZCTA-level variables were used in Stage 2 of our modeling approach to assess effect measure modification by neighborhood SES (undereducated area, poverty area, >90th percentile NDI). We did not observe differences in associations between ozone and pediatric respiratory ED visits by undereducated area status when using combined or city-specific models (Fig. 2a). However, when assessing other indicators of neighborhood SES, we observed stronger associations between ozone and pediatric respiratory ED visits in poverty areas for all cities in both the combined and city-specific meta-regressions (Fig. 2b) and stronger associations in areas designated as above the 90th percentile of the NDI with the exception of Dallas in city-specific models (Fig. 2c). These differences in association between SES strata were not statistically significant; however, associations in low SES groups had very wide posterior intervals resulting from very few ZCTAs designated as extremely low SES (Additional file 1: Table S1).Fig. 2


Ozone and childhood respiratory disease in three US cities: evaluation of effect measure modification by neighborhood socioeconomic status using a Bayesian hierarchical approach
Effect modification by categorical indicators of neighborhood SES using combined and city-specific models. a: association between ozone and pediatric respiratory ED visits in undereducated areas (low SES) and non-undereducated areas (high SES). b: association between ozone and pediatric respiratory ED visits in poverty areas (low SES) and non-poverty areas (high SES). c: association between ozone and pediatric respiratory ED visits in areas above the 90th percentile of the NDI (low SES) and in areas below the 90th percentile (higher SES). Odds ratios and 95% posterior intervals per 25 ppb ozone are presented. Black points and error bars represent ORs and 95% PIs in low SES areas; gray points and bars represent ORs and 95% PIs in areas of higher SES. Undereducated areas: ≥ 25% the adult population (≥25 years old) with less than a 12th grade education. Poverty area: ≥ 20% households living below the Federal Poverty Line. Abbreviations: ED, Emergency Department; NDI, Neighborhood Deprivation Index; SES, socioeconomic status; ZCTA, Zip Code Tabulation Area
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Related In: Results  -  Collection

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getmorefigures.php?uid=PMC5382444&req=5

Fig2: Effect modification by categorical indicators of neighborhood SES using combined and city-specific models. a: association between ozone and pediatric respiratory ED visits in undereducated areas (low SES) and non-undereducated areas (high SES). b: association between ozone and pediatric respiratory ED visits in poverty areas (low SES) and non-poverty areas (high SES). c: association between ozone and pediatric respiratory ED visits in areas above the 90th percentile of the NDI (low SES) and in areas below the 90th percentile (higher SES). Odds ratios and 95% posterior intervals per 25 ppb ozone are presented. Black points and error bars represent ORs and 95% PIs in low SES areas; gray points and bars represent ORs and 95% PIs in areas of higher SES. Undereducated areas: ≥ 25% the adult population (≥25 years old) with less than a 12th grade education. Poverty area: ≥ 20% households living below the Federal Poverty Line. Abbreviations: ED, Emergency Department; NDI, Neighborhood Deprivation Index; SES, socioeconomic status; ZCTA, Zip Code Tabulation Area
Mentions: Categorical ZCTA-level variables were used in Stage 2 of our modeling approach to assess effect measure modification by neighborhood SES (undereducated area, poverty area, >90th percentile NDI). We did not observe differences in associations between ozone and pediatric respiratory ED visits by undereducated area status when using combined or city-specific models (Fig. 2a). However, when assessing other indicators of neighborhood SES, we observed stronger associations between ozone and pediatric respiratory ED visits in poverty areas for all cities in both the combined and city-specific meta-regressions (Fig. 2b) and stronger associations in areas designated as above the 90th percentile of the NDI with the exception of Dallas in city-specific models (Fig. 2c). These differences in association between SES strata were not statistically significant; however, associations in low SES groups had very wide posterior intervals resulting from very few ZCTAs designated as extremely low SES (Additional file 1: Table S1).Fig. 2

View Article: PubMed Central - PubMed

ABSTRACT

Background: Ground-level ozone is a potent airway irritant and a determinant of respiratory morbidity. Susceptibility to the health effects of ambient ozone may be influenced by both intrinsic and extrinsic factors, such as neighborhood socioeconomic status (SES). Questions remain regarding the manner and extent that factors such as SES influence ozone-related health effects, particularly across different study areas.

Methods: Using a 2-stage modeling approach we evaluated neighborhood SES as a modifier of ozone-related pediatric respiratory morbidity in Atlanta, Dallas, & St. Louis. We acquired multi-year data on emergency department (ED) visits among 5–18 year olds with a primary diagnosis of respiratory disease in each city. Daily concentrations of 8-h maximum ambient ozone were estimated for all ZIP Code Tabulation Areas (ZCTA) in each city by fusing observed concentration data from available network monitors with simulations from an emissions-based chemical transport model. In the first stage, we used conditional logistic regression to estimate ZCTA-specific odds ratios (OR) between ozone and respiratory ED visits, controlling for temporal trends and meteorology. In the second stage, we combined ZCTA-level estimates in a Bayesian hierarchical model to assess overall associations and effect modification by neighborhood SES considering categorical and continuous SES indicators (e.g., ZCTA-specific levels of poverty). We estimated ORs and 95% posterior intervals (PI) for a 25 ppb increase in ozone.

Results: The hierarchical model combined effect estimates from 179 ZCTAs in Atlanta, 205 ZCTAs in Dallas, and 151 ZCTAs in St. Louis. The strongest overall association of ozone and pediatric respiratory disease was in Atlanta (OR = 1.08, 95% PI: 1.06, 1.11), followed by Dallas (OR = 1.04, 95% PI: 1.01, 1.07) and St. Louis (OR = 1.03, 95% PI: 0.99, 1.07). Patterns of association across levels of neighborhood SES in each city suggested stronger ORs in low compared to high SES areas, with some evidence of non-linear effect modification.

Conclusions: Results suggest that ozone is associated with pediatric respiratory morbidity in multiple US cities; neighborhood SES may modify this association in a non-linear manner. In each city, children living in low SES environments appear to be especially vulnerable given positive ORs and high underlying rates of respiratory morbidity.

Electronic supplementary material: The online version of this article (doi:10.1186/s12940-017-0244-2) contains supplementary material, which is available to authorized users.

No MeSH data available.


Related in: MedlinePlus