Setting: According to anecdotal evidence, waterpipe smoking may lead to the initiation of cigarette smoking among young people. This hypothesis is yet to be examined using an appropriate study design and a theoretical model for behavioral change.
Objective: To compare the risk of cigarette smoking initiation among waterpipe-only smokers and never smokers in a school-based sample of adolescents from Irbid, Jordan.
Methods: A total of 1454 cigarette-naïve participants were drawn from a longitudinal study on smoking behavior conducted in Irbid among 1781 seventh graders who were enrolled at baseline (2008) and completed the study questionnaire on smoking behavior annually until 2011. Grouped time-survival analysis was used to compare the risk of subsequent initiation of cigarette smoking between waterpipe smokers (n = 298) and never smokers (n = 1156) using adjusted hazard ratios (aHRs) and 95% confidence intervals (95%CI).
Results: Risk of initiation of cigarette smoking among waterpipe smokers was significantly higher than among 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. The risk of initiating cigarette smoking increased with increase in the frequency of waterpipe smoking (P for linear trend < 0.001).
Conclusions: Waterpipe smoking led to the initiation of cigarette smoking among this cohort of Jordanian adolescents; the effect was dose-dependent.