Effects of water-pipe smoking on lung function: a systematic review and meta-analysis.

BACKGROUND Although common in many Middle Eastern countries, water-pipe tobacco smoking, commonly known as water-pipe smoking (WPS), is increasingly popular in Western cultures. The primary objective of this study was to systematically review the effects of WPS on lung function. The secondary objective was to compare the effects of WPS and cigarette smoking on lung function. METHODS We conducted a systematic review using the approach of the Cochrane Collaboration to search for, select, and abstract studies. We conducted two separate meta-analyses comparing water-pipe smokers with nonsmokers, and water-pipe smokers with cigarette smokers for each of three spirometric measurements (FEV₁, FVC, and FEV₁/ FVC). We used the standardized mean difference (SMD) to pool the results. RESULTS Six cross-sectional studies were eligible for this review. Compared with no smoking, WPS was associated with a statistically significant reduction in FEV₁ (SMD = -0.43; 95% CI, -0.58 to -0.29; equivalent to a 4.04% lower FEV₁%), a trend toward lower FVC (SMD = -0.15; 95% CI, -0.34 to 0.04; equivalent to a 1.38% reduction in FVC%), and lower FEV₁/ FVC (SMD = -0.46; 95% CI, -0.93 to 0.01; equivalent to a 3.08% lower FEV₁/ FVC). Comparing WPS with cigarette smoking, there was no statistically significant difference in FEV₁, FVC, and FEV₁/ FVC. The six studies suffered from methodologic limitations. CONCLUSIONS WPS negatively affects lung function and may be as harmful as cigarette smoking. WPS, therefore, is likely to be a cause of COPD.