Sex-specific initiation rates of tobacco smoking and its determinants among adults from a Middle Eastern population: a cohort study.

OBJECTIVES

To assess the initiation rate and determinants of tobacco smoking among adults.

METHODS

In the Tehran Lipid and Glucose Study, a population-based cohort from Iran, 6101 participants ≥ 18 years old who had never smoked tobacco at baseline (phase II: 2002-2006) were followed until phase VI (2015-2018). Sex-specific initiation rates per 1000 person-years for self-reported tobacco smoking and hazard ratios (HR) for its potential determinants (using Cox proportional hazards models) were calculated.

RESULTS

The age- and sex-adjusted smoking initiation rate was 13.77 [95% confidence interval (CI) 12.59-14.94] per 1000 person-years, of which 78% was attributed to water pipe use. Initiation rate was remarkably higher among men [19.1 (16.9-21.2)] than women [8.3 (7.4-9.2)] and declined in older age-groups. Among both genders, being married was protective [men: HR 0.67 (CI 95% 0.48-0.92); women: 0.58 (0.45-0.74)], while intermediate-level education (compared with high level) [men: 1.61 (1.14-2.26); women: 1.33 (0.95-1.84, p value = 0.092)] and passive smoking [men: 1.76 (1.36-2.28); women: 1.82 (1.42-2.33)] increased the risk. Educational intervention decreased the risk among women [0.74 (0.58-0.94)].

CONCLUSIONS

The majority of adult smoking initiators started smoking with water pipe. The initiation rate was remarkably higher in men and younger age-groups. Passive smoking, being single and lower education were risk factors. Educational intervention was protective among women.