The effect of depression status change on daily cigarette smoking amount according to sex: an eleven-year follow up study of the Korea Welfare Panel Study.

Background: In the past decade, the Korean smoking rate has only decreased by 3%, despite several smoking control policies. There is a need for such policies to take smokers' psychological characteristics into account. Depression is a well-known contributor to failed smoking cessation. This study aimed to examine the effect of smokers' depression status changes on their daily cigarette smoking amount (DCA).

Methods: This study used a sample drawn from the Korea Welfare Panel Study (KoWePS) waves 3 (2008) to 13 (2018). The DCA refers to the number of the cigarettes smoked per day at the time of the survey. Depression was measured using an 11-item version of the Center for Epidemiologic Studies Depression Scale (CESD-11). A generalized estimating equation (GEE) model was employed to analyse the effect of change of depression status on DCA.

Results: The 2008 baseline included a total of 1821 participants: 1645 males and 176 females. The Yes→No male depression status group had lower DCA (β = - 0.631, p-value = 0.0248) than the No→No group. The Yes→No male depression status group that began smoking before age 19 had lower DCA (β = - 0.881, p-value: 0.0089) than the No→No group that started smoking before 19.

Conclusions: We found that a change from depressed to non-depressed and non-depressed to depressed status is associated with decreasing and increasing DCA among men, respectively. Also, for smokers who began smoking before 19 years of age, the subgroup that went from depressed to non-depressed had much a lower DCA than general smokers. Thus, when treating people participating in smoking cessation programs, counsellors should check for depression symptoms and encourage individuals to pursue depression treatment simultaneously.