Nicotine dependence and biochemical exposure measures in the second trimester of pregnancy

Kwok, T'ng Chang; Taggar, Jaspal; Cooper, Sue; Lewis, Sarah; Coleman, Tim

Abstract

Introduction: The Heaviness of Smoking Index (HSI) is validated to measure nicotine dependence in nonpregnant smokers,
and in these smokers, mean salivary and serum cotinine levels are related by a ratio of 1.25. However, as nicotine metabolism
increases during gestation, these findings may differ in pregnancy. We investigated the validity of HSI in pregnancy by comparing
this with 3 biochemical measures; and in a search for a less-invasive cotinine measure in pregnancy, we also explored the
relationship between mean blood and salivary cotinine levels.
Methods: Cross-sectional analyses using baseline data from the Smoking, Nicotine, and Pregnancy Trial. Participants were
16–46 years old, 12–24 weeks gestation, smoked more than 5 cigarettes per day and had exhaled carbon monoxide (CO) readings
of at least 8 ppm. Linear regression was used to examine correlations between HSI and blood cotinine, and salivary cotinine
and exhaled CO. Correlation between blood and salivary cotinine was investigated using linear regression through the origin.
Results: HSI scores were associated with blood cotinine (R2 = 0.20, n = 662, p < .001), salivary cotinine (R2 = 0.11, n = 967,
p < .001), and exhaled CO (R2 = 0.13, n = 1,050, p < .001). Salivary and blood cotinine levels, taken simultaneously, were highly
correlated (R2 = 0.91, n = 628, p < .001) and the saliva:blood level ratio was 1.01 (95% CI 0.99–1.04).
Conclusions: Correlations between HSI and biochemical measures in pregnancy were comparable with those obtained outside
pregnancy, suggesting that HSI has similar validity in pregnant smokers. Salivary and blood cotinine levels are roughly equivalent
in pregnant smokers.

Citation

Kwok, T. C., Taggar, J., Cooper, S., Lewis, S., & Coleman, T. (2014). Nicotine dependence and biochemical exposure measures in the second trimester of pregnancy. Nicotine & Tobacco Research, 16(2), https://doi.org/10.1093/ntr/ntt127

• Journal Article Type: Article
• Publication Date: Apr 1, 2014
• Deposit Date: Apr 3, 2014
• Publicly Available Date: Apr 3, 2014
• Journal: Nicotine & Tobacco Research
• Print ISSN: 1462-2203
• Electronic ISSN: 1469-994X
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 16
• Issue: 2
• DOI: https://doi.org/10.1093/ntr/ntt127
• Public URL: https://nottingham-repository.worktribe.com/output/996362
• Publisher URL: http://ntr.oxfordjournals.org/content/16/2/145.abstract