Biomarkers of tobacco smoke exposure and asthma severity in adults.
BACKGROUND
Tobacco biomarkers including serum cotinine and urinary 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL) have been used in research settings.


OBJECTIVE
The goal of the study was to examine the association of cotinine and NNAL with asthma outcomes in the U.S. adult population.


METHODS
A cross-sectional design was used, using data from the National Health and Nutrition Examination Survey, 2007-2008, with participants aged >20 years with self-reported asthma (N=456). Past-year asthma exacerbations and emergency room/urgent care visits for asthma were examined. Analyses were conducted in 2013.


RESULTS
Among adult asthmatics, 50.3% reported a past-year asthma attack (61.8% smokers, 46.6% nonsmokers, p=0.029). Among these, 24.7% reported a past-year emergency/urgent visit for asthma (34.7% smokers, 20.1% nonsmokers, p=0.034). Median concentrations of cotinine and creatinine-adjusted NNAL (NNAL/Cr) were significantly higher in those with a past-year asthma attack (0.43 ng/mL and 7.28 pg/mL) than in those without (0.06 ng/mL and 2.26 pg/mL), and highest in those with past-year emergency/urgent visits (0.93 ng/mL and 28.14 pg/mL). Among nonsmokers, increasing levels of log cotinine or log NNAL/Cr, adjusted for demographics, were significantly associated with past-year asthma exacerbation (log cotinine OR=1.46 [95% CI=1.1, 1.92]; log NNAL/Cr OR=1.42 [95% CI=1.07, 1.88]) and past-year emergency/urgent visit (log cotinine OR=1.95 [95% CI=1.32, 2.88]; log NNAL/Cr OR=1.58 [95% CI=1.23, 2.02]). Among smokers, increasing biomarker levels were not significantly associated with either outcome.


CONCLUSIONS
In a population-based cross-sectional analysis, increased cotinine and NNAL were found to be associated with asthma exacerbation and healthcare use in nonsmokers with asthma. If these findings are confirmed in prospective studies, these biomarkers might be candidates for clinical indicators of risk of asthma.
Department of Internal Medicine, University of California, Davis, Sacramento.
Gwendolyn
G
Ho
Hao
H
Tang
John A
JA
Robbins
Elisa K
EK
Tong
D000328:Adult; D000368:Aged; D001249:Asthma / Q000503:physiopathology*; D015415:Biomarkers / Q000378:metabolism; D003367:Cotinine / Q000097:blood*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009602:Nitrosamines / Q000652:urine*; D009749:Nutrition Surveys; D011725:Pyridines / Q000652:urine*; D012189:Retrospective Studies; D012720:Severity of Illness Index; D012907:Smoking / Q000453:epidemiology; D014028:Tobacco Smoke Pollution / Q000009:adverse effects* / Q000032:analysis; D055815:Young Adult
D015415:Biomarkers; D009602:Nitrosamines; D011725:Pyridines; D014028:Tobacco Smoke Pollution; C099565:4-(methylnitrosamino)-1-(3-pyridyl)-1-butan-1-ol; D003367:Cotinine