ASSOCIATION BETWEEN EXPOSURE TO ENVIRONMENTAL TOBACCO SMOKE AND BIOMARKERS OF CARDIOVASCULAR DISEASE IN NHANES 1999-2006 Open Access

Abstract

Background: Exposure to environmental tobacco smoke (ETS) is among the leading causes of preventable poor health and premature death in the developed world. Current knowledge pertaining to the association between ETS exposure and early biomarkers of cardiovascular disease is limited.

Objective: This study's purpose was to investigate the association between ETS exposure and the target biomarker concentration.

Methods: Using data from 1996-2006 U.S. National Health and Nutrition Examination Survey (NHANES), adult (≥20 years) non-smokers were selected for analysis (N=4,986). We used weighted multiple linear regression to investigate the association between the target biomarker concentration and ETS exposure, controlling for other predictors of cardiovascular disease risk (diabetes, hypertension, high cholesterol, obesity, and physical activity status). We defined ETS exposure as either self-reported ETS exposure at home or serum cotinine tertile and tested these in separate models.

Results: In the homocysteine models, the regression coefficient of the ETS exposure at home variable was statistically significant and the β coefficient (95% confidence interval) of the ETS term was 0.48 (5.12, 6.57), p-value <0.01. In the cotinine model, the β for the cotinine categories were -0.02 (-0.29, 0.25), p-value=0.88 for the moderate category and 0.34(0.06, 0.63), p =0.02 for the high category. The ETS variable coefficients were not statistically significant in the c-reactive protein models.

Conclusions: We found significant associations between ETS exposure and serum homocysteine, an early biomarker of cardiovascular risk, in a large, representative sample of U.S. adult non-smokers. These findings build on previous studies reporting significant associations and illustrate the need for continued public health strategies to control ETS exposure.

Table of Contents

Contents
Introduction ......................................................................................................................... 1
Methods.............................................................................................................................. 6
Results ................................................................................................................................ 8
Discussion ......................................................................................................................... 10
Conclusions ....................................................................................................................... 12
References ......................................................................................................................... 13

Tables
Table 1. Unweighted frequencies (weighted %) of missing and non-missing observations, Adult (age ≥20) non-smokers, NHANES 1999-2006 (N=4,986)........................................17
Table 2. Weighted frequencies of selected categorical variables, adult (age ≥20) non-smokers, NHANES 1999-2006 (N=4,986)........................................................................18
Table 3. Weighted descriptive statistics of selected continuous variables, adult (age ≥20) non-smokers, NHANES 1999-2006 (N=4,986)................................................................20
Table 4. Characteristics of adult (age ≥20) non-smokers (weighted % unless noted) by home ETS exposure status, NHANES 1999-2006 (N=4,986)...........................................21
Table 5. Weighted frequencies (%) by cotinine tertile and weighted geometric mean (geometric standard deviation) concentrations of serum cotinine, homocysteine, c-reactive protein, and total cholesterol among adult (≥20) non-smokers, by ETS exposure status at home, NHANES 1999-2006................................................................................22
Table 6. Results of multivariable linear regression of serum homocysteine and ETS exposure at home, adult (≥20) non-smokers, NHANES 1999-2006 (Adjusted R²= 0.28) 23
Table 7. Multivariable linear regression analysis of serum homocysteine by serum cotinine level, among adult (≥20) non-smokers, NHANES 1999-2006 (Adjusted R²= 0.28)................................................................................................................24
Table 8. Multivariable linear regression analysis of serum homocysteine by ETS exposure status at home and workplace, among adult (≥20) non-smokers, NHANES 1999-2006 (Adjusted R²=0.20)..........................................................................................25
Table 9. Multivariable analysis of serum c-reactive protein level among nonsmoker adults (≥ 20 years) by ETS exposure at home, NHANES 1999-2006 (Adjusted R²=0.10).........26
Table 10. Linear regression analysis of c-reactive protein among adult (≥20) non-smokers by ETS exposure status at home and work, NHANES 1999-2006 (Adjusted R²=0.13)...27
Table 11. Linear regression analysis of c-reactive protein among adult (≥20) non-smokers by serum cotinine level, NHANES 1999-2006 (Adjusted R²=0.10)...................28

Figures
Figure 1. Histogram of residuals from multiple linear regression model of homoysteine and ETS exposure at home................................................................................................29
Figure 2. Linear regression model for log Homoysteine, by ETS exposure status at home...................................................................................................................................30
Figure 3. Scatter plot of predicted versus observed values from multiple linear regression of log homoysteine and ETS exposure at home................................................................31
Figure 4 & 5. Linear regression model for homocysteine, by serum cotinine category....32
Figure 6. Linear regression model for log homocysteine, by serum cotinine category.....34
Figure 7. Linear regression model for homocysteine, by ETS exposure status at home and workplace...........................................................................................................................35
Figure 8 & 9. Linear regression model for log homocysteine, by ETS exposure status at home and workplace..........................................................................................................36
Figure 10. Linear regression model for c-reactive protein by ETS exposure status at home...................................................................................................................................38
Figure 11 & 12. Linear regression model for c-reactive protein by ETS exposure status at home and workplace..........................................................................................................39
Figure 13. Scatter plot: log homocysteine by log cotinine................................................41
Figure 14. Scatter plot c-reactive protein by log continine...............................................42

About this Master's Thesis

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School	Rollins School of Public Health
Department	Environmental Health
Degree	MPH
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, Public Health Environmental Sciences
Keyword	C-REACTIVE PROTEIN HOMOCYTEINE COTININE ETS
Committee Chair / Thesis Advisor	Riederer, Anne, Emory University
Committee Members	Tolbert, Paige, Emory University
Partnering Agencies	Emory University schools, faculty or affiliated programs CDC

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