A systematic review on the evidence of waterpipe smoking and the risk of cardiovascular diseases

Abstract

Background The prevalence of waterpipe smoking is increasing rapidly worldwide, and so will the detrimental health effects associated with it. Pulmonary and cardiovascular diseases have been documented as the most likely outcome of regular waterpipe smoking. The former has been extensively studied. However, the latter only gained attention more recently after 2010, and there is no systematic review. The objective of this study was to review the studies on the acute and long-term cardiovascular effects associated with waterpipe smoking and assess the quality of their evidence that could be used to support waterpipe smoking legislation in the future.

Methods A literature search on the online databases yielded 25 studies, 16 of which investigated the acute effects and 9 of them examined the long-term usage of waterpipe smoking. The GRADE approach was used to assess the quality of the evidence on the long-term cardiovascular effects. Thereafter, the evidence was assessed for causality using Hill’s criteria.

Results 13 and 8 short-term experimental studies reported statistically significant increase in heart rate and blood pressure respectively. The other 2 surrogate markers of cardiovascular effects, nicotine and carbon monoxide levels were also increased after waterpipe smoking. The magnitude of blood pressure change was closely related to plasma nicotine levels. Long-term observation studies showed that stroke and coronary heart disease were the two most common outcomes for long-term waterpipe smoking. The odds ratio of developing some sort of cardiovascular ailments in these studies varied with one study showing as low as 0.7 (95%CI 0.3-1.9) with another as high as 3.75 (95%CI 1.5-9.2). The quality of the observational studies was graded from low to very low. There was also insufficient evidence to confirm causation based on Hill’s criteria.

Conclusion The poor quality of evidence from the long-term observational studies does not support a causal relationship between waterpipe smoking and cardiovascular diseases. Nonetheless, there is substantial evidence from the acute studies to confirm that waterpipe smoking can cause an immediate change in the cardiovascular system.