Goldenson NI, et al. - This study contemplated the potential connection between the use of e-cigarettes displaying higher nicotine concentrations, with subsequent increases in the frequency and intensity of combustible cigarette smoking and vaping. Preliminary evidence was yielded with regard to the use of e-cigarettes with higher nicotine concentrations by youths possibly raising the subsequent frequency and intensity of smoking and vaping.

Methods

• The plot of this research was a prospective cohort study.
• It recruited students from 10 high schools in the Los Angeles, California, metropolitan area.
• Surveys were administered during 10th grade in the spring (baseline) and 11th grade in the fall (6-month follow-up) of 2015 to students who reported using e-cigarettes within the past 30 days and the nicotine concentration level they used at baseline.
• The exposure consisted of self-report of baseline e-cigarette nicotine concentration of none (0mg/mL), low (1-5mg/mL), medium (6-17mg/mL), or high (≥18mg/mL) typically used during the past 30 days.
• The main measure comprised of the frequency of combustible cigarette smoking and e-cigarette use within the past 30 days (0 days [none], 1-2 days [infrequent], or ≥3 days [frequent]) and daily intensity of smoking and vaping (number of cigarettes smoked per day, number of vaping episodes per day, and number of puffs per vaping episode) at the 6-month follow-up.

Results

• 181 students were recruited (96 boys [53.0%] and 85 girls [47.0%]; mean [SD] age, 16.1 [0.4] years).
• A correlation was determined between each successive increase in nicotine concentration (none to low, low to medium, and medium to high) vaped with a 2.26 (95% CI, 1.28-3.98) increase in the odds of frequent (vs no) smoking and a 1.65 (95% CI, 1.09-2.51) increase in the odds of frequent (vs no) vaping at follow-up, after adjustment for baseline frequency of smoking and vaping and other relevant covariates.
• A link was brought to light between the use of e-cigarettes with high (vs no) nicotine concentration with a greater number of cigarettes smoked per day at follow-up (adjusted rate ratio [RR], 7.03; 95% CI, 6.11-7.95).
• There appeared to be a connection with a substantially greater number of vaping episodes per day due to the use of low (adjusted RR, 3.32; 95% CI, 2.61-4.03), medium (adjusted RR, 3.32; 95% CI, 2.54-4.10), and high (adjusted RR, 2.44; 95% CI, 1.63-3.24) nicotine concentrations (vs no nicotine) at baseline.
• The data yielded similar results for the number of puffs per vaping episode for low (adjusted RR, 2.05; 95% CI, 1.41-2.70), medium (adjusted RR, 3.39; 95% CI, 2.66-4.11), and high (adjusted RR, 2.23; 95% CI, 1.42-3.03) nicotine concentrations.