Although the prevalence of male adult tobacco smoking in South Korea has declined from 66.3% in 1998 to 36.7% in 2018 [1], the prevalence of male adult electronic cigarette (EC) users in Korea increased from 2.0% in 2013 to 4.4% in 2017 [2]. Most EC users begin this habit assuming that it will assist them to cease smoking tobacco [3]. However, the main reason for the failure of smoking cessation in this group is associated with the level of nicotine dependence.

In this issue, Hwang et al. [4] investigate nicotine dependence among exclusive combustible cigarette (CC) users, EC users, and dual users using a questionnaire and urine cotinine as a biochemical marker. Their study compares the difference between Heaviness of Smoking Index with urine cotinine.

Among those who currently smoke any type of cigarette: 89.4%, 1.4%, and 9.2% were exclusive CC users, exclusive EC users, and dual users, respectively. Most exclusive CC users (about 69.2%) were in their 30s to 50s, while most exclusive EC users (about 68.0%) and dual users (about 68.4%) were in their 20s to 30s. The geometric mean of urine cotinine was highest among dual users (1,356.4 ng/mL), followed sequentially by exclusive CC users (1,270.3 ng/mL), and exclusive EC users (867.7 ng/mL). The differences in the average number of cigarettes smoked per day and Heaviness of Smoking Index scores were not statistically significant among the three groups. Although the urine cotinine analysis showed differences in nicotine dependence between the three groups, the differences were not clear in the survey questionnaire.

The authors rationalized this result due to the lack of a detailed questionnaire on EC use (e.g., EC use frequency, number of puffs, nicotine concentrations, vaporizing power, flavor, etc.).

Currently, EC technology is developing steadily, with future devices likely to deliver high-concentrations of nicotine more efficiently. Moreover, the number of new types of cigarettes, including ECs and “heat-not-burn” tobacco products, is increasing [5]. Developing new evaluation tools to measure nicotine dependence among dual and poly-users is essential.

In this study, 64.7% of dual users had tried to quit smoking for more than 24 hours in a day. Smoking cessation consultations for dual users need to be more strategic. New evaluation tools are needed to assess the amount of smoking and nicotine dependence of dual users or poly-users more efficiently.