Smokeless tobacco in South Asia – the measurement of dependence, sociocultural influences and cardiovascular consequences

Introduction: Despite very high smokeless tobacco (ST) consumption in South Asia (SA), there are significant gaps in our knowledge regarding the measurement of ST dependence, sociocultural influences, and consequences associated with the use of South Asian ST products. Aim: To improve our understanding of ST use and dependency, sociocultural determinants and consequences associated with their use in South Asia. Methods: My thesis comprised of three empirical studies. I carried out psychometric assessments of three ST dependency scales, using data collected from a convenience sample of adult ST users in India. In the same sample, I quantitatively measured selected sociocultural variables and assessed their association with ST use and quit practices. Finally, I conducted meta-analyses of longitudinal observational studies to examine causal associations between ever use of ST and cardiovascular outcomes, both globally and by geographical subgroups. Results: Among the scales, internal consistency was highest for Oklahoma Scale for Smokeless Tobacco Dependence (OSSTD). The scales were significantly correlated with each other, and showed positive associations with heaviness and consistency of ST use. Based on exploratory factor analyses (EFA), OSSTD was a unidimensional measure of ST dependence in an Indian context. The sociocultural survey showed that having ST users as close peers and no household restrictions on use adversely influenced quit attempts and quit intentions respectively, in adjusted models. In the meta-analyses, ever use of ST was associated with a 40% increased risk of incident ischaemic health disease (IHD) in SA, which was not found in other geographical regions. Conclusions: South Asian ST products are likely highly addictive, and sociocultural factors may be associated with fewer quit attempts made. In addition to cancer, ST use also increases the risk of cardiovascular disease outcomes. More research relevant to ST control is needed from SA, particularly given the adverse health consequences associated with use.