Most adult deaths in India involve vascular disease, pulmonary tuberculosis, or other respiratory disease. In the first major study of how smoking causes death in India, Vendhan Gajalakshmi from Chennai's Epidemiology Research Centre and her colleagues compared the tobacco smoking of 43,000 men (from both urban and rural areas) who had died of various diseases in the late 1990s with that of 35,000 living men (the control group).
In the urban study area, the death rates from medical causes of ever smokers were double those of never smokers. The risks were substantial both for cigarette smoking (the main urban habit) and for bidi (small cigarettes popular in Asia) smoking. Of this excess mortality among smokers, most involved respiratory disease (chiefly tuberculosis) or vascular disease (chiefly heart attack). Smoking also caused similar excesses of respiratory and vascular mortality in the rural study area.
Vendhan Gajalakshmi comments: "More than 4000 of these deaths were from TB, but if smokers had had the same low risks as non-smokers there would have been fewer than 2000 TB deaths. Half the extra TB deaths were at ages 25-54. In total, about a quarter of all smokers are killed by smoking at ages 25-69-those killed at these ages lose 20 years of life on average."
Co-author Richard Peto from the University of Oxford,UK, adds: "About a billion people worldwide are carrying live tuberculosis infection in their lungs, but if they do not smoke then most will never become seriously ill from TB. Smoking increases the danger that any TB infection already in the lungs will get out of control and cause clinical TB, which can kill and can easily be spread to other people. In some parts of the world the main way smoking kills people is by damaging the lung's defences against chronic TB infection. Our study indicates that in rural India about 12% of smokers (but only 3% of non-smokers) will die prematurely from TB. In urban India the corresponding risks are 8% and 2%."
Another co-author, Prabhat Jha, of the University of Toronto, Canada comments: "Tuberculosis still causes about 1.6 million deaths a year worldwide, including more than a million in Asia, 400,000 in Africa, and 100,000 in the Americas and Europe. Not only in Asia and Africa, but also throughout America and Europe, smoking will increase the number of people who develop clinical TB themselves and can then infect others, unless they are properly treated and cured." (All quotes by e-mail, they do not appear in the published paper).
Contacts:
(North America) Dr Prabhat Jha, Centre for Global Health Research, University of Toronto, Canada; T) 1-416-864-6042; M) 1-416-839- 0332 or Jessica Whiteside, University of Toronto Public Affairs; T) +1 416-978-5948; E) Jessica.whiteside@utoronto.ca
(Europe) Professor Sir Richard Peto, CTSU, Nuffield Department of Clinical Medicine, University of Oxford, UK; T) 44-0-186-540-4801; M) 44-0-777-196-0329; E) secretary@ctsu.ox.ac.uk.
(India) Dr. Vendhan Gajalakshmi, Epidemiological Research Center, new no 37, Outer Circular Road, KG Colony, Chennai 600 010, India; T) 91-442-644-6030; M) 91-984-016-0050; E) gajaerc@rediffmail.com
Journal
The Lancet