Background: Globally, there are 10 million new cases of tuberculosis (TB) disease annually and 95% of cases occur in low- and middle-income countries (LMIC). More than 1 billion people use tobacco, and 80% of tobacco users reside in LMIC. Smoking approximately doubles the risk of TB disease and is associated with excess mortality during TB treatment. We aimed to estimate the proportion of annual incident TB cases and TB mortality attributable to tobacco smoking in high burden TB countries.

Methods: To estimate population attributable fractions (PAF), we obtained country specific estimates of TB incidence and TB mortality rates from the WHO 2015 Global TB Report. Country specific smoking prevalence was estimated from WHO 2015 tobacco surveillance reports and the Tobacco Atlas. Risk ratios for the effect of smoking on TB incidence and TB mortality were obtained from previously published meta-analyses. Country specific PAF of smoking for TB disease were age and sex adjusted.

Results: In high burden countries during 2014, an estimated 4.5 million adults developed TB disease and 163,000 people died from TB. An estimated 740 million adult smokers lived in those high burden countries in 2014. We estimated that tobacco smoking was attributable for 17.7% (95% confidence interval [CI] 8.6-21.9%) of TB cases and 15.0% (95% CI 1.9-31.6%) of TB mortality. Of the high burden countries, Russia had the highest proportion of smoking attributable TB disease (31.8%, 95% CI 16.0-37.8%) and death (28.1%, 95% CI 3.8-51.3%). India had the greatest absolute number of TB cases (233,000) and TB deaths (7,400) attributable to smoking. Men (30.5%, 95% CI 14.9%-36.9%) had a greater proportion of TB cases attributable to smoking than women (4.7%, 95% CI 1.9%-6.2%).

Conclusion: In high-burden TB countries, nearly one-sixth of all TB cases and TB deaths were attributable to smoking. Our findings highlight the need for tobacco control in high TB burden regions and specifically among patients with TB. Reaching key populations and integrating smoking cessation efforts into TB programs will be essential to achieve global TB control goals.