Korean J Fam Med 2016; 37(3): 171-176  https://doi.org/10.4082/kjfm.2016.37.3.171
Discrepancy between Self-Reported and Urine-Cotinine Verified Smoking Status among Korean Male Adults: Analysis of Health Check-Up Data from a Single Private Hospital
Youngju Kim1, Yoon-Jung Choi1, Seung-Won Oh2, Hee-Kyung Joh3,4, Hyuktae Kwon2, Yoo-Jin Um1, Sang Hyun Ahn1, Hyun Joo Kim1, Cheol Min Lee2,*
1Department of Family Medicine, Seoul National University Hospital, Seoul, Korea
2Department of Family Medicine, Healthcare System Gangnam Center, Seoul National University Hospital, Seoul, Korea
3Department of Medicine, Seoul National University College of Medicine, Seoul, Korea
4Department of Family Medicine, Seoul National University Health Service Center, Seoul, Korea
Cheol Min Lee Tel: +82-2-2112-5668, Fax: +82-2-2112-5635, E-mail: bigbangx@snuh.org
Received: February 28, 2015; Revised: August 21, 2015; Accepted: September 27, 2015; Published online: May 20, 2016.
© Korean Academy of Family Medicine. All rights reserved.

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Background: Enquiry into smoking status and recommendations for smoking cessation is an essential preventive service. However, there are few studies comparing self-reported (SR) and cotinine-verified (CV) smoking statuses, using medical check-up data. The rates of discrepancy and under-reporting are unknown.

Methods: We performed a cross-sectional study using health examination data from Healthcare System Gangnam Center, Seoul National University Hospital in 2013. We analyzed SR and CV smoking statuses and discrepancies between the two in relation to sociodemographic variables. We also attempted to ascertain the factors associated with a discrepant smoking status among current smokers.

Results: In the sample of 3,477 men, CV smoking rate was 11.1% higher than the SR rate. About 1 in 3 participants either omitted the smoking questionnaire or gave a false reply. The ratio of CV to SR smoking rates was 1.49 (95% confidence interval [CI], 1.38–1.61). After adjusting for confounding factors, older adults (≥60 years) showed an increased adjusted odds ratio (aOR) for discrepancy between SR and CV when compared to those in their twenties and thirties (aOR, 5.43; 95% CI, 2.69–10.96). Educational levels of high school graduation or lower (aOR, 2.33; 95% CI, 1.36–4.01), repeated health check-ups (aOR, 1.45; 95% CI, 1.03–2.06), and low cotinine levels of <500 ng/mL (aOR, 2.03; 95% CI, 1.33–3.09), were also associated with discordance between SR and CV smoking status.

Conclusion: Omissions and false responses impede the accurate assessment of smoking status in health check-up participants. In order to improve accuracy, it is suggested that researcher pay attention to participants with greater discrepancy between SR and CV smoking status, and formulate interventions to improve response rates.

Keywords: Smoking; Cotinine; Surveys and Questionnaires; Self Report; Mass Screening

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