BACKGROUND: Long-term smoking, including in India, shortens life by at least 10 years. However, the relationship between tobacco use and major causes of adult morbidity remains largely uncharted in many countries.
METHODS: We examined 4.6 million adults aged 20 to 69 interviewed in 2014 by the Registrar General of India’s nationally-representative study. The survey covered 8858 urban blocks or villages selected randomly from the 2011 Census. We calculated sex-specific age-standardized rates of current smoking or chewing tobacco and performed multivariate adjusted log-binomial regression to estimate their prevalence ratios (PR) with morbidities self-reported in the last year. The five morbidities examined were cardiovascular and respiratory disease, cancer, tuberculosis and arthritis. We documented residual confounding covariates (locality, education, hypertension, diabetes and health insurance coverage) by quantifying changes in log PR in stepwise analyses.
RESULTS: 13% of adult men smoked, while only 1% of women did. Chewing was more prevalent (men: 20%, women: 7%). After adjusting for covariates, smoking was significantly associated with morbidity in men: cardiovascular (PR 2.03, 99%CI 1.91-2.14), respiratory (PR 1.90, 1.76-2.05), tuberculosis (PR 1.78, 1.56-2.03), cancer (PR 1.56, 1.33-1.84), and arthritis (PR 1.41, 1.29-1.55). In women, chewing tobacco was significantly linked to tuberculosis (PR 1.54, 1.29-1.84) and arthritis (PR 1.53, 1.42-1.65). These associations were minimally attenuated by potential confounders. Chewing tobacco was modestly associated with arthritis in men (PR 1.33, 1.21-1.45). By contrast, in both sexes the linkages of chewing to other morbidities were largely explained by covariates.
CONCLUSIONS: Smoking is a leading cause of morbidity in Indian men, contributing to a range of health issues. In women, chewing tobacco is linked to tuberculosis and arthritis. As some morbidities may lead to tobacco cessation, the true strength of these associations could be even greater that observed. Prospective documentation of the large hazards of tobacco use on death and morbidity is urgently needed.