Factors associated with smoking intensity among adult smokers: findings from the longitudinal cohort of the Tehran lipid and glucose study

Background Smoking is a significant public health problem, and there is a scarcity of documents regarding its severity, particularly in developing countries.

This study aimed to determine factors related to the number of cigarettes consumed daily by adult smokers in Tehran.

Methods This study was conducted within the framework of the longitudinal study of Tehran Lipid and Glucose Study (TLGS).

The study included 786 adult smokers living during four consecutive follow-ups from 2005 to 2016.

The intensity of smoking was measured by the number of cigarettes consumed daily by adult smokers.

Data analysis was done longitudinally and based on the mixed effects zero-inflated discrete Weibull (ZIDW) regression model.

Results The mean age of the individuals was 40.35 ± 12.68 years, and 643 (81.8%) of them were men.

Also, 52.7% of individuals were daily smokers, 15.6% were occasional smokers, and 31.7% were non-smokers who became smokers during the study.

Variables of age 1.005 (95%CI: 1.001–1.008), gender of male 1.196 (95%CI: 1.051–1.39), and marital status (divorced/widowed vs. single) 1.168 (95%CI: 1.015–1.39) were positively associated with smoking intensity.

Education level (master and higher vs. illiterate) 0.675 (95%CI: 0.492–0.926)), employment status (student vs. unemployed) 0.683 (95%CI: 0.522–0.917), (housewife vs. unemployed) 0.742 (95%CI: 0.606–0.895), (Unemployed with income vs. unemployed) 0.804 (95%CI: 0.697, 0.923), implementation of smoking prohibition regulations (yes vs. no) 0.88 (95%CI: 0.843–0.932), and history of cardiovascular disease in male relatives (yes vs. no) 0.85 (95%CI: 0.771–0.951) were associated with lower smoking intensity.

Conclusion We showed that demographic factors are associated with the intensity of smoking among adults and should be considered in policymakers’ intervention programs to reduce smoking and quit smoking.