Relationship between women's smoking and laryngeal disorders based on the urine cotinine test: results of a national population-based survey

OBJECTIVES There is a possibility of underestimation in the smoking rate surveyed by self-reported questionnaires. This study investigated the difference between the Korean female smoking rate as determined by self-reports and that determined by a biochemical test and elucidated the relationship between women's smoking and laryngeal disorders. DESIGN Nationwide cross-sectional survey. SETTING 2008 Korea National Health and Nutrition Examination Survey. PARTICIPANTS 1849 women who completed the health survey, urinary cotinine test and laryngoscope examinations. MAIN OUTCOME MEASURE This study defined smokers as those with urine cotinine contents of 50 ng/mL and over. Confounding factors included age, level of education, household income, occupation and problem drinking in the past year. For statistical tests, OR and 95% CI were presented by using complex samples logistic regression. RESULTS While there was no relationship between smoking as determined by a self-reported questionnaire and laryngeal disorders, smoking as determined by the urine cotinine test had a significant relationship with laryngeal disorders (p<0.05). After all the confounding factors were adjusted, those with urine cotinine concentrations of over 50 ng/mL had a 2.1 times higher risk of laryngeal disorders than those with urine cotinine concentrations of <50 ng/mL (OR=2.05, 95% CI 1.11 to 3.78) (p<0.05). CONCLUSIONS This national cross-sectional study verified that smoking is a significant risk factor for laryngeal disorders. Longitudinal studies are required to identify the causal relationship between smoking and laryngeal disorders.