Background and objectives With high rates of use and uncertain consequences, valid electronic cigarette (e-cigarette) use frequency and addiction measures for adolescents are needed. This cross-sectional study examined correlations for multiple measures of adolescent e-cigarette use with nicotine exposure quantified with salivary cotinine levels.
Methods Adolescents (N=173, age 13–18) who reported past-month e-cigarette use were recruited from the San Francisco Bay Area. Participants self-reported: (1) days of e-cigarette use in a typical month, (2) number of e-cigarette sessions in a typical day (sessions per day; SPD) and the (3) E-Cigarette Addiction Severity Index (EASI). Participants also completed the 10-item Penn State Electronic Cigarette Dependence Index (ECDI), which we examined in full and as a 2-item Heaviness of Vaping Index (HVI; the sum of the ECDI items on use frequency and time to first vaping on wakening). Sessions per month (SPM) were calculated using days per month and SPD. Cotinine levels, SPD and SPM were log-transformed.
Results Among frequency measures, SPM correlated most strongly with cotinine (r=0.59), followed closely by days per month (r=0.58) and SPD (r=0.57), p<0.001. Among dependence measures, the EASI correlated most strongly with cotinine (r=0.51), closely followed by the ECDI and HVI (r’s=0.50), all p’s<0.001.
Conclusions Adolescents’ reports of frequency of e-cigarette use and degree of addiction correlated significantly with cotinine as a biomarker of nicotine exposure. We recommend the EASI and days per month as brief general measures. SPM and the ECDI are more extensive measures that may yield a more nuanced understanding of use.
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Contributors EAV conceptualised and conducted data analyses, drafted the initial manuscript, and reviewed and revised the manuscript. JJP critically reviewed and revised the manuscript for important intellectual content. MLR conceptualised and designed the study, coordinated and supervised data collection, and reviewed and revised the manuscript for important intellectual content. All authors approved the final manuscript as submitted and agree to be accountable for all aspects of the work.
Funding All phases of this study were supported by the National Institute on Drug Abuse (Award #R21 DA040718). JJP is also supported by the National Cancer Institute (Award #R01CA217165). MLR and EAV are also supported by the California Tobacco Related Diseases Research Program (Award #s P0504871 and 28FT-0015).
Competing interests JJP has provided consultation to pharmaceutical and technology companies that make medications and other treatments for quitting smoking and has served as an expert witness in lawsuits against the tobacco companies. MLR has consulted for Pfizer on research involving smoking cessation medication and for Carrot, Inc., which makes a tobacco cessation device.
Patient consent for publication Not required.
Ethics approval Study procedures were approved by the University of California, San Francisco Institutional Review Board (IRB). We obtained IRB approval to waive parental consent, per the state of California law 6929(b), which permits the treatment of minors for substance use without parental permission. Cessation information and local treatment options were provided.
Provenance and peer review Not commissioned; externally peer reviewed.