Determinants of Waterpipe and Cigarette Smoking Progression among a School Based Sample of Adolescents in Irbid, Jordan: A Three-Year Longitudinal Study (2008-2011)

BACKGROUND: Based on anecdotal evidence, waterpipe may provide gateway to cigarette smoking onset among youth. This hypothesis is yet to be examined using appropriate study design and a theoretical model of behavioral change. AIM: To compare the risk of cigarette smoking initiation for waterpipe-only and never-smokers among a school-based sample of adolescents from Irbid, Jordan. METHODS: A total of 1454 cigarette naive participants were drawn from the Irbid longitudinal study of smoking behavior out of 1781 seventh-graders who were enrolled at baseline (2008) and completed the study questionnaire of smoking behavior annually through 2011. Grouped-time survival analysis was used to compare the risk of a subsequent initiation of cigarette smoking between waterpipe smokers (n=298) and never smokers (n=1156) using Adjusted Hazard Ratio [AHR] and 95% Confidence Interval [95%CI]. RESULTS: Risk of cigarette initiation among waterpipe smokers was significantly higher than never-smokers after adjusting for potential confounders (AHR: 1.67; [95% CI: 1.46-1.92]). The association between waterpipe and cigarette smoking initiation was dose dependent. As frequency of waterpipe smoking increased, the probability of cigarette initiation increased (P for linear trend < 0.001). CONCLUSIONS: Waterpipe smoking temporally predicted cigarette initiation among this cohort of Jordanian adolescents and this effect was dose-dependent.