Residential Roadway Proximity and Lung Function Decline in Pediatric Cystic Fibrosis Open Access

Flores, Julie (Spring 2019)

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Cystic fibrosis (CF) is a genetic disease that causes ongoing decline in lung function until patients ultimately experience respiratory failure. Air pollution exposure is thought to be  detrimental to anyone with lung disease, and this is particularly true for people with CF. Research indicates that environmental factors account for about half of variations in lung function of CF patients. To ensure better outcomes for this group, there is a need to quantify the effect of air pollution exposure on rate of decline in lung function.



Demographic and clinical data were collected from pediatric patients of the Emory University + Children’s Healthcare of Atlanta CF Care Center (n = 98). Data were collected from the period between 2013-2017. Residential distance to the closest major roadway was used as a proxy for air pollution exposure. Spirometry test results were used to calculate each subject’s annual baseline lung function scores by finding the mean of the highest percent predicted value of forced expiratory volume in one second (FEV1) result from each quarter. Annual rates of decline (ROD) in FEV1 for each subject were determined by calculating the differences between subsequent baseline values.  Linear regression, one-way non-parametric analysis (ANOVA), linear mixed models, Pearson correlation coefficients, and Chi-square tests were used to examine the association between residential roadway proximity and ROD. Other characteristics known to influence CF disease progression were included in the analysis, such as gender, race, insurance status, income, bacterial acquisition status, and CF-related diabetes (CFRD) status.



No linear correlations were observed among raw or transformed roadway proximity and ROD data. In a mixed-model analysis utilizing a Chi-square test, living within 570 meters of a major roadway were observed to experience a mean annual ROD of -2.87% (95% CI: -4.21, -1.53) while subjects residing further away had a mean ROD of -0.94% (95% CI: -1.53, -0.36) (p=0.011). Using mixed-model and non-parametric one-way analyses respectively, chronic infection with methicillin-resistant S. aureus (MRSA) (p=0.006) and diagnosis of CFRD (p=0.037) were also observed to have statistically significant associations with ROD. Self-reported income levels were found to be significant for residential roadway proximity (p=0.048) but not ROD. Sex, race, insurance status, and P. aeruginosa infection status did not have a significant association with residential roadway proximity or ROD.



Pediatric patients with CF who live within a region observed to have increased levels of airway pollution experience an annual ROD in lung function that is 3.05 times greater than that of children living in areas where roadway air pollution exists at background levels. This vulnerability ultimately will affect their quality of life and increase the burden of care. Further research amongst a larger cohort and multiple centers is warranted to better understand this effect, and support public policy that guides air quality measures.

Table of Contents

Table of Contents

Introduction/Statement of Problem.. 1

Problem Statement 3

Purpose of the Study. 3

Review of the Literature. 4

Roadway Proximity. 4

Air Pollution Exposure and Cystic Fibrosis. 6

Methodology. 9

Subject Selection and Data. 9

Geomapping. 10

Statistical Analysis. 11

Results. 12

Conclusions. 13

References. 17

Appendices. 22

List of Definitions. 22

Table 1: Summary of Background Normalized Data. 22

Figure 1: Average Rate of Decline in Lung Function. 23

Figure 2: Average Rate of Decline vs. Residential Roadway Proximity. 24

Figure 3: Rate of Decline and Distance from Major Roadway. 25


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