Patterns of water-pipe and cigarette smoking initiation in schoolchildren: Irbid longitudinal smoking study.

Introduction: Tobacco use remains a major public health problem worldwide. Water-pipe smoking is spreading rapidly and threatening to undermine the successes achieved in tobacco control.

Methods: A school-based longitudinal study in the city of Irbid, Jordan, was performed from 2008 to 2010. All seventh-grade students in 19 randomly selected schools, out of a total of 60 schools in the city, were enrolled at baseline and surveyed annually.

Results: Of the 1781 students enrolled at baseline 1,701 (95.5%) were still in the study at the end of the second year of follow-up (869 boys, median age at baseline 13 years). Ever and current water-pipe smoking were higher than those of cigarette smoking at baseline (ever smoking: 25.9% vs. 17.6% and current smoking: 13.3% vs. 5.3% for water-pipe and cigarette smoking, respectively; p < .01 for both) but cigarette smoking caught up by the second year of follow-up (ever smoking: 46.4% vs. 44.7%; p = .32 and current smoking: 18.9% vs. 14.9%; p < .01). Water pipe-only smokers at baseline were twice as likely to become current cigarette smokers after 2 years compared with never smokers (relative risk (RR) = 2.1; 95% CI = 1.2, 3.4). A similar pattern was observed for cigarette-only smokers at baseline (RR = 2.0; 95% CI = 0.9, 4.8).

Conclusions: Prevalence of water-pipe and cigarette smoking increased dramatically over the 2-year follow-up period with similar patterns in boys and girls, although girls had lower prevalence in all categories. Water-pipe smoking at baseline predicted the progress to cigarette smoking in the future and vice versa.