India has lost fewer people to tuberculosis annually than previously estimated, according to cause-of-death data and calculations by India that the World Health Organisation (WHO) has used to revise downwards its estimates for global TB deaths.

The calculations based on the Sample Registration Survey (SRS) covering a nationwide sample population of about eight million people have estimated that India’s annual TB deaths have ranged between 400,000 and 300,000 since 2015, and not over 500,000 estimated earlier.

The WHO’s World TB Report 2023 released on Tuesday has estimated that TB caused 1.3 million deaths worldwide, revising downwards estimates of global TB deaths since 2010. The main reason for these lowered estimates is revisions to estimates for India based on cause-of-death data from SRS for 2014-19 released by the Indian government earlier this year, the WHO said.

The earlier WHO estimates of the number of TB deaths in India from 2000 to 2019 were based on a Global Burden of Disease (GBD) study by the US-based Institute of Health Metrics and Evaluation. “Estimates of the percentage of total deaths in India that were caused by TB in the official SRS reports are lower than those in GBD 2019,” the WHO said, explaining its new estimates.

A public health expert in India who was not associated with the WHO TB report or the India calculations said the SRS provides information about the proportion of deaths due to TB among all deaths in the sample population surveyed.

“One issue with relying on the proportion of deaths is that increases in other causes of deaths — such as heart disease or something else — might lower the proportion from TB,” the expert who requested not to be named said. “But other data could be combined with the SRS data for estimates of annual TB deaths.”

The WHO 2022 TB report had estimated 1.6 million global TB deaths in 2021, 32 per cent (512,000) in India, while the WHO 2021 TB report had estimated 1.5 million global TB deaths, 34 per cent (510,000) in India.

Despite the lowered estimates in the 2023 report, the WHO said the net decrease in TB-related deaths from 2015 to 2019 was 19 per cent, falling far short of the WHO End TB Strategy milestone of a 75 per cent reduction by 2025.

The report said about 50 per cent of TB patients and their households face catastrophic financial costs due to the illness, defined as direct medical expenditure and indirect costs such as income losses that amount to more than 20 per cent of household income.