title: The effects of waterpipe tobacco smoking on health outcomes: a systematic review.
abstract: BACKGROUND
  There is a need for a comprehensive and critical review of the literature to inform scientific debates about the public health effects of waterpipe smoking. The objective of this study was therefore to systematically review the medical literature for the effects of waterpipe tobacco smoking on health outcomes.
  
  
  METHODS
  We conducted a systematic review using the Cochrane Collaboration methodology for conducting systematic reviews. We rated the quality of evidence for each outcome using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology.
  
  
  RESULTS
  Twenty-four studies were eligible for this review. Based on the available evidence, waterpipe tobacco smoking was significantly associated with lung cancer [odds ratio (OR) = 2.12; 95% confidence interval (CI) 1.32-3.42], respiratory illness (OR = 2.3; 95% CI 1.1-5.1), low birth-weight (OR = 2.12; 95% CI 1.08-4.18) and periodontal disease (OR = 3-5). It was not significantly associated with bladder cancer (OR = 0.8; 95% CI 0.2-4.0), nasopharyngeal cancer (OR = 0.49; 95% CI 0.20-1.23), oesophageal cancer (OR = 1.85; 95% CI 0.95-3.58), oral dysplasia (OR = 8.33; 95% CI 0.78-9.47) or infertility (OR = 2.5; 95% CI 1.0-6.3) but the CIs did not exclude important associations. Smoking waterpipe in groups was not significantly associated with hepatitis C infection (OR = 0.98; 95% CI 0.80-1.21). The quality of evidence for the different outcomes varied from very low to low.
  
  
  CONCLUSIONS
  Waterpipe tobacco smoking is possibly associated with a number of deleterious health outcomes. There is a need for high-quality studies to identify and quantify with confidence all the health effects of this form of smoking.
authors.affiliation: Department of Medicine, State University of New York at Buffalo, Buffalo, NY 14215, USA. elieakl@buffalo.edu
authors.forename: Elie A
authors.initials: EA
authors.lastname: Akl
authors.forename: Swarna
authors.initials: S
authors.lastname: Gaddam
authors.forename: Sameer K
authors.initials: SK
authors.lastname: Gunukula
authors.forename: Roland
authors.initials: R
authors.lastname: Honeine
authors.forename: Philippe Abou
authors.initials: PA
authors.lastname: Jaoude
authors.forename: Jihad
authors.initials: J
authors.lastname: Irani
mesh_terms: D003430:Cross-Sectional Studies; D003469:Culture; D004938:Esophageal Neoplasms / Q000453:epidemiology; D005260:Female; D006526:Hepatitis C / Q000453:epidemiology; D006801:Humans; D007248:Infertility, Male / Q000453:epidemiology; D008175:Lung Neoplasms / Q000453:epidemiology; D008297:Male; D009303:Nasopharyngeal Neoplasms / Q000453:epidemiology; D009369:Neoplasms / Q000453:epidemiology*; D016017:Odds Ratio; D011247:Pregnancy; D011256:Pregnancy Outcome; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D001749:Urinary Bladder Neoplasms / Q000453:epidemiology