India's "verbal autopsies" are crude but invaluable How does India look after the living if it knows little about how they die, writes Anjana Ahuja The exact manner of my grandfather's passing about 60 years ago is a matter of some mystery. He possibly died of kidney failure, although his sudden decline fuelled rumours that he may not have departed wholly of his own accord. That, sadly, remains the nature of death in India: of uncertain cause, at home and without a hospital visit. Cremation swiftly follows, rendering autopsies impossible. But such uncertainty is not ideal for an emerging economy whose greatest asset is a young, vibrant workforce. How does a country look after the living if it knows next to nothing about how they die? That is the thinking behind the Million Deaths Survey, which involves knocking on doors and talking to families who have lost relatives aged under 70. The little-known survey does not finish until the end of this month but a stream of interim results is already challenging assumptions about how the world's second most populous nation is losing its citizens. The MDS was dreamt up by Prabhat Jha, an epidemiologist from the University of Toronto, who used to work for the World Bank and the World Health Organisation. In 2001 he convinced India's census bureau that, when its surveyors go door-to-door to collect information on births and deaths, they should also ask about recent deaths in the household and interview relatives, armed with a checklist of symptoms. The yes-no results of these "verbal autopsies" are sent to doctors, who make a retrospective diagnosis. Relatives can often recall their losses in heartbreaking detail, especially if it is a child or young adult. As the decade of door-knocking draws to a close, the journal Nature has summarised findings from the half a million deaths analysed so far. The top killers of Indians aged 30-69 are vascular disease (heart disease and stroke); chronic respiratory conditions; tuberculosis; and cancer. But there are surprises. HIV/Aids kills a quarter of the number that the UN reports for India; while malaria kills at least 13 times the WHO estimate of 13,000 (WHO's data are based on hospital deaths; but most who reach hospital survive). Snakebite and suicide cost more young lives than official estimates suggest. Smoking is a rural menace as well as an urban one: traditional roll-ups slice roughly seven years off national life expectancy. As well as doubling the risk of cancer and heart disease, as in richer countries, tobacco doubles the risk of death by tuberculosis. This grim epidemiological exoticism appears to be unique to India. Deadly geographical quirks are also emerging: the industrialised northern state of Haryana, criss-crossed with trucking routes, is afflicted by road accidents. Suicide rates in the south are 10 times those in the north. Only when such anomalies are measured can they be addressed. The MDS, funded in part by the Bill & Melinda Gates Foundation, is one of the largest and most important mortality counts ever undertaken . The verbal autopsy may be a crude technique - WHO has questioned Prof Jha's malaria figures but accepts its own are an underestimate - but it is cheap and portable. Brazil, South Africa and China want their own versions. Prof Jha, born in India and raised in Canada, worked under Sir Richard Peto, who helped reveal the link between smoking and lung cancer, and continues his mentor's tradition of uncovering uncomfortable truths. His number-crunching flagged up India's missing 12m girls, feared lost since 1985 to selective abortion or female infanticide. Antimalarials, snakebite antidotes and smoking prevention have all climbed the Indian healthcare spending agenda, as a result of MDS findings. And, like many brilliant pieces of science, the MDS started with a personal question - Prof Jha's émigré mother wondering how her father, in rural India, had died. So vivid were her relatives" descriptions that, when Prof Jha reread his mother's notes decades later, he realised his grandfather had suffered a stroke. While the Ahuja dynasty continues its morbid musings on the passing of its patriarch, it is comforting to know that science will bring closure for millions of others. The writer was named best science commentator at the 2013 Comment Awards last month