The Relationship between Waterpipe and Cigarette Smoking in Low and Middle Income Countries: Cross-Sectional Analysis of the Global Adult Tobacco Survey

Introduction: Waterpipe tobacco smoking is receiving growing attention due to accumulating evidence suggesting increasing prevalence in some populations and deleterious health effects. Nevertheless, the relationship between waterpipe and cigarette smoking remain unknown, particularly in low and middle income countries. Materials and Methods: We analysed waterpipe and cigarette smoking using data from Global Adult Tobacco Survey, a household survey of adults aged >= 15 years conducted between 2008-2010 in LMICs. Factors associated with waterpipe and cigarette use were assessed using multiple logistic regression. Factors associated with the quantity of waterpipe and cigarette smoking were assessed using log-linear regression models. Results: After adjusting for age, gender, residence, education, occupation and smokeless tobacco use, waterpipe smoking was significantly higher among cigarette users than in non-cigarette users in India (5.6% vs. 0.6%, AOR 13.12, 95% CI 7.41-23.23) and Russia (6.7% vs. 0.2%, AOR 27.73, 95% CI 11.41-67.43), but inversely associated in Egypt (2.6% vs. 3.4%, AOR 0.21, 95% CI 0.15-0.30) and not associated in Vietnam (13.3% vs. 4.7%, AOR 0.96, 95% CI 0.74-1.23). Compared to non-cigarette smokers, waterpipe smokers who also used cigarettes had more waterpipe smoking sessions per week in Russia (1.3 vs. 2.9, beta coefficient 0.31, 95% CI 0.06, 0.57), but less in Egypt (18.2 vs. 10.7, beta coefficient -0.45, 95% CI -0.73, -0.17) and Vietnam (102.0 vs. 79.3, beta coefficient -0.31, 95% CI -0.56, -0.06) and similar amounts in India (29.4 vs. 32.6, beta coefficient -0.12, 95% CI -0.46, 0.22). Conclusions: Waterpipe smoking is low in most LMICs but important country-level differences in use, including concurrent cigarette smoking, should be taken into account when designing and evaluating tobacco control interventions.