Exposure to fine particulate matter from traffic in early life and childhood pneumonia-Survival analysis of an Atlanta birth cohort Öffentlichkeit
Kennedy, Caitlin (2016)
Published
Abstract
Introduction: Pneumonia is one of the leading causes of global infant morbidity and mortality in children less than 5 years old. Environmental risk factors for pneumonia include indoor air pollution exposures as well as ambient traffic related exposures in urban areas. The objective of this study is to examine the association between residential particulate matter exposures and time to first pneumonia event during the first two years of life for children living in the greater Atlanta area.
Methods: Time to first clinical diagnosis of pneumonia was analyzed in a survival analysis using Cox proportional hazards regression. The outcome was defined as the first diagnosis of pneumonia after the first 28 days of life based on ICD-9 codes 480-486 in the medical record. Clinical data came from 22,520 children enrolled in the Kaiser Air Pollution and Pediatric Asthma Study (KAPPA), a historical birth cohort of children born between 2000 and 2010 and enrolled in the Kaiser Permanente Georgia HMO. Exposures to fine particulate matter (PM2.5) from traffic emissions were modeled based on 2011 pollution estimates created using a research line-source dispersion model (RLINE) at 250-meter resolution.
Results: The effect estimate for the association between primary PM2.5 exposure and first pneumonia event by age two was modestly elevated for a 1 microgram per cubic meter (µg/m3) change in PM2.5. The Hazard Ratio and 95% Confidence Interval for this association were estimated to be 1.17 (0.93, 1.47) in a no interaction, un-stratified model controlling for child sex, child race, maternal asthma status, maternal prenatal smoking status, maternal education, city region, and neighborhood socioeconomic status. Average PM2.5 exposure was 1.17 µg/m3 PM2.5 with a standard deviation of 0.27 µg/m3. Approximately 10% of the total 22,520 children were diagnosed with pneumonia during their first two years of life.
Conclusions: These results provide limited evidence for a harmful association between traffic-related primary PM2.5 and pneumonia in the first two years of life. Our findings are consistent with the literature and suggest more research is needed to understand the relationship between chronic, early life exposures to fine particulates from vehicle emissions and early childhood pneumonia.
Table of Contents
Chapter 1: Introduction and Background…………………………………….1
Case definition………………………………………………………………...…..1
Particulate matter exposure…………………………………………………....2
Particulate matter and children's health…………………………………….3
Literature Review Summary………………………………………………..…..4
Chapter 2: Methods……………………………………………………………….7
KAPPA cohort data……………………………………………………...…….....7
Exposure data……………………………………………………………...……...7
Description of the covariates……………………………………………......…8
Statistical modeling……………………………………………………………....9
Chapter 3: Results………………………………………………………..……...12
Descriptive statistics…………………………………………………………..…12
Model selection…………………………………………………………………...13
Figure 1: Pneumonia diagnoses by year ………………………………...….14
Figure 2: Pneumonia diagnoses by season………………………………....14
Modeling results………………………………………………………….…….…15
Figure 3: Kaplan-Meier curve ………………………………………………....16
Table 1: Descriptive statistics……………………………………………….…18
Table 2: Hazard ratio effect estimates for final model………………..….19
Table 3: All possible subsets results for adjusted Hazard Ratio….…....20
Chapter 4: Discussion and Conclusion…………………………………..…..21
Chapter 5: References………….………………………………………………..26
Appendix I: Complete Literature Review…………………………………....33
Appendix II: SAS Code……………………………………………………….….44
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