Comparison of CO breath testing and women's self-reporting of smoking behaviour for identifying smoking during pregnancy

Usmani, Z.C., Craig, P., Shipton, D. and Tappin, D. (2008) Comparison of CO breath testing and women's self-reporting of smoking behaviour for identifying smoking during pregnancy. Substance Abuse Treatment, Prevention, and Policy, 3, 4. (doi:10.1186/1747-597X-3-4) (PMCID:PMC2265678)

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Abstract

Background: Healthcare services often use a carbon monoxide (CO) breath test to validate self-reported smoking and to assess reductions in smoking habit. A cut-off level of >= 8 parts per million (p. p. m.) is used to identify smoking. This cut-off requires further validation in pregnant women. Methods: Data on self-reported smoking were assessed in conjunction with breath CO levels. Subjects in the study were 2548 women attending antenatal booking during 12 months. Results: 546/2584 (21.4%) women self-reported as current smokers. A cut-off of 8 ppm identified only 325/546 self-reported smokers (sensitivity 59.4%). 27/2002 self-reported non-smokers had levels greater than 8 ppm (specificity 98.7%). Sensitivity and specificity analysis revealed that CO cut-off levels of 2 or 3 p. p. m. resulted in the best sensitivity and specificity for discriminating apparent smokers and non-smokers. A cut-off of 2 p. p. m. would have identified 468/546 of self-reported smokers (sensitivity 86%). 206/2002 self-reported non-smokers had levels > 2 ppm (specificity 90 %). If all these women were 'true' smokers, the real prevalence of smoking in pregnancy was 26.5% (752/2548) and 27% of true smokers provided false answers to the self-reported question at maternity booking. Conclusion: At 8 ppm, many smokers are missed and there may be gross underestimating of levels of smoking in a pregnant population. Results emphasise the need to support a lower cut-off level for the breath CO test closer to 2 or 3 p. p. m. These cut-offs may be more appropriate in the antenatal clinic setting, and are in line with recent recommendations in the non-pregnant population.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Tappin, Professor David and Craig, Dr Pauline and Shipton, Dr Deborah
Authors: Usmani, Z.C., Craig, P., Shipton, D., and Tappin, D.
College/School:College of Medical Veterinary and Life Sciences > School of Medicine, Dentistry & Nursing > Clinical Specialities
Journal Name:Substance Abuse Treatment, Prevention, and Policy
Publisher:BioMed Central
ISSN:1747-597X
ISSN (Online):1747-597X
Copyright Holders:Copyright © 2008 Usmani et al
First Published:First published in Substance Abuse Treatment, Prevention, and Policy 3: 4
Publisher Policy:Reproduced under a Creative Commons License

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