Long-term trends in past-month smoking prevalence following tobacco control legislation in Chile: an age-period-cohort analysis

Chile has one of the highest smoking prevalences in the Americas despite implementing two major tobacco control laws (2006 and 2013) following ratification of the WHO Framework Convention on Tobacco Control. This study analyses long-term trends in past-month smoking prevalence in Chile using an age-period-cohort (APC) approach and examines changes in age and cohort patterns across periods defined by these tobacco control policies. We pooled individual-level data from 284,671 participants aged 12–64 years across fifteen waves of the Chilean National Study of Drug Use in the General Population (ENPG, 1994–2022). Three logit APC models with robust standard errors were estimated separately for males and females: a main-effects model and two models with interactions between a policy-period variable (1994–2004 pre-legislation; 2006–2012 under Law 20105; 2014–2022 under Law 20660) and age and cohort, respectively. Predicted probabilities were estimated and compared graphically. Sensitivity analyses used alternative groupings of age and cohort. Smoking prevalence peaked in 2000 (44% overall; 48% males, 40% females) and declined thereafter, reaching 27% in 2022 with near-convergence between sexes. APC analysis showed the highest predicted probabilities of past-month smoking among the 1954–1959 birth cohort, with sustained declines across cohorts born after 1983. Following the more comprehensive 2013 legislation, predicted probabilities of past-month smoking were significantly lower than in the pre-legislation period among females aged 37–44 and males aged 29–40, and among cohorts born between 1966 and 1989. No statistically significant differences were observed for the period under the 2006 partial legislation. Long-term declines in smoking prevalence in Chile, particularly following the 2013 comprehensive tobacco control legislation, were associated with marked changes in age and cohort smoking patterns. The findings suggest that comprehensive, rather than incremental, policy packages are linked to greater changes in population-level smoking behaviour and highlight the role of generational change. Sustaining these gains will require stricter regulation of emerging nicotine products and continued youth-focused prevention.