Decreasing Trends and Age-period-cohort Effects on Smoking in Thailand

Tobacco control is one of the effective means of cancer prevention. Overall prevalence trend of smoking in Thailand has decreased over time which is partly due to tobacco control policy in the country (Levy et al., 2008; Sangthong et al., 2011). This change of smoking trend can also be affected by age structure and birth cohort but they have never been examined in Thailand. Age-period-cohort analysis using data from multiple cross-sectional surveys can be used to describe trends of interesting events (Yang, 2008). Age structure could account for the increasing or decreasing trend of smoking. Age effects reflect biological and social processes of aging and represent developmental changes across the life course. Period effects are defined as variation over time periods or calendar years that influence all age groups simultaneously. Cohort effects are associated with a change in rates in successive age groups in successive time periods whereby different cohorts have different exposures. The latter two effects are important in the context of time trends where cohort effects are associated with long-term exposures. In Thailand, national surveys on smoking behavior