Smoking Trends among Thailand's Youths from 1996-2015: An Age-Period-Cohort Analysis of National Health Surveys.

Background: This study aimed to investigate secular trends of smoking among Thailand's youths.

Methods: We combined 8 datasets from national representative surveys between 1996 and 2015. Multi-stage cluster sampling was applied in all studies. Overall, 231459 participants aged 11-26 yr were included and analyzed. Participants were classified as current smokers if they responded "yes" to the question "Do you currently smoke?", and former smoker if they reported no current smoking but had smoked previously. Age-period-cohort (APC) models were used to estimate age, period, and cohort effects on smoking for investigating secular trend of smoking.

Results: The prevalence of smoking tended to decrease over time. Among those aged 11-14, the prevalence of current and former smoking was low but not negligible. Rates of underage smoking remained quite steady, around 3.8% in 1996 and 3.6% in 2015. The results of the APC model show that the prevalence of smoking among young male cohorts was lower than in older cohorts.

Conclusion: Thailand's tobacco control program has been effective in deterring youths from smoking. The prevalence of smoking in this population needs to be reduced further though, something achieved by reorienting tobacco consumption prevention campaigns towards this age group.