Cigarette smoking trajectories among adolescents and young adults in the Islamic Republic of Iran.

ABSTRACT

Background: Cigarette smoking follows a progressive pattern throughout the lifetime; most adult smokers started smoking during adolescence. Aim: To understand the cigarette smoking trajectories and their predictors among adolescents and young adults in the Islamic Republic of Iran. Methods: Using data from the Tehran Lipid and Glucose Study, we followed 1169 adolescents (12-18 years old) into their young adulthood (28-32 years old), from 2002 to 2016. We used cigarette smoking as the outcome variable for group-based trajectory modelling. After detecting the trajectories, we investigated the effects of independent variables, namely, individual employment; education; physical activity; and paternal smoking, employment and education, on the trajectories. We analysed the data using STATA version 16 and SPSS version 26. Results: Three trajectories were detected non-smokers (79%), experimenters (12%) and escalators (9%). Boys were approximately 3 times (OR = 2.94, 95% CI 2.32-3.24, P < 0.001) and 25 times (OR = 25.00, 95% CI 23.92-26.08, P < 0.001), respectively, more likely than girls to be in the experimenter and escalator groups. Receiving a university education decreased the odds of being in the escalator trajectory for 18% (OR = 0.82, 95% CI -0.04-0.96, P = 0.002) of the study participants. Employment after high school increased the odds by approximately two folds for the experimenter (OR = 2.00, 95% CI 1.42-2.50, P = 0.01) and escalator (OR = 2.33, 95% CI 1.33-2.93, P = 0.03) trajectories. Paternal smoking was associated with 1.88 and 2.23, respectively, increased odds of experimenting and escalating smoking among the adolescents. Conclusion: Iranian adolescents follow 3 cigarette smoking trajectories into young adulthood non-smokers, experimenters and escalators. Male sex, employment after high school, and living with a smoker father were associated with unfavourable smoking patterns. Findings from this study provide valuable insights for designing targeted interventions to reduce cigarette smoking among adults and adolescents in the Islamic Republic of Iran.