Background This is a secondary data analysis designed as a longitudinal study aimed at investigating the effects of depression and self-esteem on daily smoking amounts among hardcore smokers over time. Methods The subjects of this study were 264 hardcore smokers aged 19 years or older who participated in all waves of the 9th–۱۳th Korea Welfare Panel Studies. Self-report questionnaires were used to collect data. Data analyses were performed using SPSS WIN 24.0 and AMOS 18.0, and data were analyzed using a latent growth model. Results The intercept of depression and self-esteem among the subjects had statistically significant effects on the intercept of the daily smoking amount. The slope of depression and self-esteem among the subjects also had statistically significant effects on the slope of the daily smoking amount. The slope of depression indirect affected the slope of daily smoking amount via the level of self-esteem. Conclusion It is important to determine the initial levels and the rates of change of depression, self-esteem, and daily smoking amount among hardcore smokers. In order to reduce the daily smoking amount among hardcore smokers, interventions for depression and methods to improve self-esteem among hardcore smokers should be considered.

Introduction

The smoking rate among adults aged 19 or older in South Korea has decreased by only 3% over the past 10 years, from 25.3% in 2007 to 22.3% in 2017. The smoking rate among adult males in 2017 remained particularly high at 38.1% (Korea Centers for Disease Control and Prevention, 2019). Despite strong smoking control policies in South Korea, there have been only slight declines in the smoking _rates, which has convincingly been argued to be attributable to hardcore smokers with no intention to quit. In particular, hardcore smokers have become more dependent on smoking over time because of their nicotine addiction, making it difficult for them to comply with smoking control policies (Hughes, 2001). Effectively controlling hardcore smokers has been pointed out as an important issue with regard to controlling the general smoking population (Warner & Burns, 2003; Chaiton, Cohen, & Frank, 2008). The term “hardcore smoker” has been defined differently by various researchers and there is still no consensus on its definition. However, “hardcore smoker” generally refers to daily smokers who have never quit smoking in the past and are not willing to quit in the future (Lund, Lund, & Kvaavik, 2011). The criteria for this definition may further include smoking more than 15 cigarettes smoked per day or long -term smoking for more than 5 years, which can serve to assess nicotine dependence. In some cases, an age requirement of 20 years or older can also be added to this definition (Lund et al., 2011; Sorg, Xu, Doppalapudi, Shelton, & Harris, 2011). Studies have reported that smokers of higher ages and with lower incomes were more likely to be hardcore smokers (Bommelé et al., 2014, 2015). It has also been reported that smokers with an earlier onset of smoking, a longer duration of smoking, and a greater amount of smoking were more likely to find it difficult to quit smoking due to nicotine dependence and were thus more likely to become hardcore smokers (Lund et al., 2011; Azagba, 2015).