Spatial Survival Analysis of Initiation Age and Prevalence of Smoking in Iran; Results from a Population Based Study

Abstract

Background: The initiation age and prevalence of cigarette smoking are two important parameters in any smoking-related policymaking domain. Methods: Dataset was extracted from STEPs survey, a population-based study conducted in Iran in 2016. A total of 27612 participants were included in the current study. We used a spatial parametric survival mixture rate cure model with doubly censoring to simultaneously assess the initiation age and prevalence of smoking. Results: The entire study population, men and women had the estimated median initiation age of 23.3 (95% CI: 22.2–24.5), 21.9 (95% CI: 21.3–22.5), and 25.5 (95% CI: 22.8–28.7) years, and the prevalence of 10.11% (95% CI: 9.3%–11.0%), 22.3% (95% CI: 21.0%–23.6%), 0.78% (95% CI: 0.62%–0.97%), respectively. The hazard of smoking initiation in men was 66% which was higher than in women (hazard ratio [HR] = 1.66, 95% CI: 1.15-2.48). The odds of smoking in men was 36.5 times greater than that of women (odds ratio [OR] = 36.5, 95% CI: 29.66-45.52). Odds of smoking decreased by 32% in the entire study population and 14% with one level increase in their education (OR = 0.68, 95% CI: 0.65-0.72) and socioeconomic status (OR = 0.86, 95% CI: 0.82-0.94), respectively. The geographical distribution of smoking initiation age varied from 21.5 to 26.37 years for the entire study population, 20.2 to 24.8 years for men, and 23.53 to 28.91 years for women. The geographical distribution of smoking prevalence varied from 5.46% to 14.98% for the entire study population, 12.82% to 30.98% for men, and 0.4% to 1.2% for women. Conclusion: The geographical distribution of smoking initiation age and prevalence showed that in different parts of the country, the initiation age and rate of smoking are different which should be considered in any preventative policy making.