title: The effects of waterpipe tobacco smoking on health outcomes: an updated systematic review and meta-analysis.
abstract: A systematic review conducted in 2008 found significant associations between waterpipe tobacco smoking and lung cancer, respiratory disease, periodontal disease and low birthweight. Since then, a number of relevant studies have been published. The objective of this study was to update the systematic review on the effects of waterpipe tobacco smoking on health outcomes.
  
  
  
  In May 2015 we electronically searched the following databases with no date restrictions: MEDLINE, EMBASE and the ISI Web of Science using a detailed search strategy with no language restrictions. We also screened the references' lists of the included studies. We included cohort, case-control and cross-sectional studies, and excluded case reports, conference abstracts, editorials and reviews. We excluded studies not conducted in humans, assessing physiological outcomes, not distinguishing waterpipe tobacco smoking from other forms of smoking or not reporting association measures. We assessed risk of bias for each included study and conducted meta-analyses for each of the outcomes of interest.
  
  
  
  We identified 50 eligible studies. We found that waterpipe tobacco smoking was significantly associated with: respiratory diseases [COPD; odds ratio (OR) = 3.18, 95% confidence interval CI = 1.25, 8.08; bronchitis OR = 2.37, 95% CI = 1.49, 3.77; passive waterpipe smoking and wheeze OR) = 1.97, 95% CI = 1.28, 3.04]; oral cancer OR = 4.17, 95% CI = 2.53, 6.89; lung cancer OR = 2.12, 95% CI = 1.32, 3.42; low birthweight (OR = 2.39, 95% CI = 1.32, 4.32); metabolic syndrome (OR 1.63-1.95, 95% CI = 1.25, 2.45); cardiovascular disease (OR = 1.67, 95% CI = 1.25, 2.24); and mental health (OR 1.30-2.4, 95% CI = 1.20, 2.80). Waterpipe tobacco smoking was not significantly associated with: oesophageal cancer (OR = 4.14, 95% CI = 0.93, 18.46); worse quality of life scores [standardized mean difference (SMD) = -0.16, 95% CI = -0.66, 0.34]; gastric carcinoma (OR = 2.16, 95% CI = 0.72, 6.47); bladder cancer (OR = 1.25, 95% CI = 0.99, 1.57); prostate cancer (OR = 7.00, 95% CI = 0.90, 56.90); hepatitis C infection (OR = 0.98, 95%0.80, 1.21); periodontal disease (OR = 3.00, 5.00); gastro-oesophageal reflux disease (OR = 1.25, 95% CI = 1.01, 1.56); nasopharyngeal carcinoma (OR = 0.49, 95% CI = 0.20, 1.23); bladder cancer (OR = 1.25, 95% CI = 0.99, 1.57); infertility (OR = 2.50, 95% CI = 1.00, 6.30); and mortality (OR = 1.15, 95% CI = 0.93, 1.43).
  
  
  
  There is accumulating evidence about the association of waterpipe tobacco smoking with a growing number of health outcomes.
authors.affiliation: Faculty of Health Sciences, American University of Beirut, Beirut, Lebanon.|Kirby Institute, University of New South Wales, Sydney, NSW, Australia.
authors.forename: Reem
authors.initials: R
authors.lastname: Waziry
authors.affiliation: Department of Primary Care and Public Health, Imperial College London, London, UK.|Academic Department of Primary Care and Population Sciences, University of Southampton, Southampton, UK.
authors.forename: Mohammed
authors.initials: M
authors.lastname: Jawad
authors.affiliation: Faculty of Medicine, American University of Beirut, Beirut, Lebanon.
authors.forename: Rami A
authors.initials: RA
authors.lastname: Ballout
authors.affiliation: Faculty of Health Sciences, American University of Beirut, Beirut, Lebanon.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Al Akel
authors.affiliation: Department of Internal Medicine, American University of Beirut, Beirut, Lebanon.|Department of Clinical Epidemiology & Biostatistics, McMaster University, Hamilton, ON, Canada.
authors.forename: Elie A
authors.initials: EA
authors.lastname: Akl
mesh_terms: D002318:Cardiovascular Diseases / Q000209:etiology*; D006801:Humans; D008603:Mental Health; D024821:Metabolic Syndrome / Q000209:etiology*; D009062:Mouth Neoplasms / Q000209:etiology*; D011788:Quality of Life; D012140:Respiratory Tract Diseases / Q000209:etiology*; D000073867:Water Pipe Smoking / Q000009:adverse effects*
keywords: Waterpipe tobacco smoking; health effects; systematic review