A systematic review of epidemiological studies on the association between smokeless tobacco use and coronary heart disease

A systematic review was conducted of epidemiological studies focusing on the association between smokeless tobacco (SLT) use and coronary heart disease (CHD) in order to summarize the evidence and to identify scope for further study in South Asian countries. PubMed and ISI Web of Science databases were searched to find epidemiological studies (cohort, case-control and cross-sectional) published until 27 October, 2011. The search revealed 592 relevant references, from which 18 epidemiological studies were selected. Among the 18 studies, 11 studies were conducted in Sweden, 4 in the USA, 1 in India, 1 in Bangladesh, and 1 study was multi-centric involving 52 countries. Twelve studies included only men and six studies included both sexes. Three studies used South Asian SLT products. Nine studies found no statistically significant positive association between SLT use and CHD, while nine studies did find a positive association. Results of these studies differed according to age, gender, and SLT constituents. Currently published research does not provide conclusive evidence regarding the association between SLT use and CHD. SLT products and usage pattern in South Asia differ from those in Western settings, and cannot be extrapolated immediately to South Asian settings.