Effectiveness of tobacco control policy interventions on tobacco use behaviours and health outcomes based on ITS research methodology: a scoping review.

OBJECTIVE: To provide an overview of the effectiveness of global tobacco control policies using Interrupted Time Series (ITS) methodology and analyse key health outcome indicators and methodological differences in ITS studies. DATA SOURCES: PubMed, Web of Science and Embase were searched for ITS studies on tobacco control policies from database inception to 1 July 2024. STUDY SELECTION: 55 English-language studies were selected based on strict inclusion criteria. DATA EXTRACTION: Three researchers extracted data on study characteristics, design, conclusions and limitations. DATA SYNTHESIS: Of the studies, 28 used monthly time intervals, 40 focused on a single time break, 47 used non-Autoregressive Integrated Moving Average models, 40 considered seasonality, 34 controlled for confounding factors and only 13 included a control group. The implementation and evaluation of tobacco control policies demonstrated considerable geographical imbalance, with Europe reporting the largest number of evaluations (n = 23), followed by Asia (n = 12) and North America (n = 10), whereas South America (n = 4), multiple regions (n = 4) and Oceania (n = 2) were markedly under-represented. Overall, policies were associated with beneficial effects across multiple health outcomes, including reductions in emergency visit rate, hospitalisation rates, secondhand smoke exposure rate and smoking prevalence, although certain outcome measures exhibited notable heterogeneity. CONCLUSIONS: ITS applications differ in time-interval selection, modelling and control of seasonality and confounding, contributing to result heterogeneity. Tobacco control policies are effective across multiple health indicators, though variability warrants further study. Future work should enhance reporting and methodological standardisation, particularly in control group use and statistical modelling, and strengthen policy implementation and evaluation in low- and middle-income countries to promote equitable global progress.