Global TB report reveals that India has been massively underestimating the disease

India has been underreporting its tuberculosis burden by almost half, it appears. The new Global Tuberculosis Report 2016 released on Thursday by the World Health Organisation updated the estimate of incidence – that is, the number of new tuberculosis cases in a year – from 1.7 million cases to 2.8 million in 2015. The report used estimates from a prevalence study done in Gujarat in 2011, the results of which were never made public till the WHO decided to use it in its global report.

The WHO also updated incidence figures for 2014 from 1.6 million cases to 2.9 million cases. This would effectively mean that the reported incidence in the national programme was only 56% in 2014 and 59% in 2015 of the actual disease burden.

The updated estimate of tuberculosis deaths, excluding deaths of HIV-positive people, is 478,000 in 2015 and 483,000 in 2014, according to the WHO report. The estimates for deaths in 2014 as per last year's Global TB Report were at half the number at only 220,000 deaths.

The government's undercount of 1.7 million new and relapse cases were reported through the Revised National Tuberculosis Control Programme. The WHO report, meanwhile, clarifies that its updated numbers for India are interim estimates, pending results from a national tuberculosis prevalence survey that is scheduled to begin in 2017.

Globally, there are an estimated 10.4 million new cases of tuberculosis. Only 6.1 million new cases were, however, notified to the national authorities. India, along with Indonesia and Nigeria, accounted for almost half of the 4.3 million gap between incident and notified cases globally.

Unpublished TB survey

In 2011, the first statewide survey on tuberculosis prevalence was conducted in Gujarat by the state government using a representative population. The results indicated a prevalence of 390 cases per one lakh population – much higher than the national estimate of 250 cases per one lakh population.

“Gujarat is among the wealthiest states in India, and given the link between overall levels of income and the burden of TB disease it seems unlikely that TB prevalence in Gujarat would be higher than the national average,” the WHO report said.

The results of this survey have not been published or made available publicly, but were only shared with the WHO in 2015. Though the results of the survey and the revised estimates may not surprise public health watchers who suspected gross undercounting of tuberculosis cases, the question remains as to why the results were not shared either online or through the media.

“The results of this survey has only just come out,” said Dr Jagdish Prasad, director general of health services with the Ministry of Health and Family Welfare.

A government official who did not wish to be named said that the health department had been sitting on the report for nearly three years.

India accounts for more than a quarter of the world's tuberculosis cases and deaths based on the global estimates, the report stated. But Prasad differs.

"Globally, WHO is saying, we account for 27% of the incidence," he said. "We do not agree with that. They should apply the same formulas and methods [that was used to calculate the revised Indian estimates] for other countries too, especially Brazil, China, South Africa, and other South Asian countries."

Private TB treatment

Other data used to revise the estimates of incidence in the Global Tuberculosis Report come from a study done earlier this year on the sales of anti-TB drugs in 2014, which estimated as many patients in treatment at private facilities as at public health centres.

Prasad acknowledges this gap in India's counting methods. “The results are not wrong," he said. "We were not picking up cases that were being treated by the private practitioners.”

"The private sector accounts for more than 60% of the TB cases," said Dr Sunil Khaparde, deputy director general of the TB control programme. "We plan to engage the private sector more in our programme. With our pilot in Mehsana, Gujarat, and Patna, the notifications have already increased substantially."

The WHO report's estimates of tuberculosis mortality are derived from numbers published by the Institute of Health Metrics and Evaluation, after adjustment for differences between WHO and IHME estimates of the total number of deaths each year. The earlier WHO estimates of TB incidence published in 2011-2015 were based on outcomes of a national consensus workshop in Delhi.

“I am convinced the higher TB estimates from India reflect the underlying reality,” said Madhukar Pai, director at McGill Global Health Programs in Canada. “For a long time, India ignored TB patients managed in the private sector, and national prevalence and drug-resistance surveys were not periodically done [unlike in other countries such as China].”

The notification rates for tuberculosis from the private sector have actually improved since it was made mandatory in 2012. There is a 34% increase in notifications in 2015, as compared to the notifications in 2013. The improved coverage of notifications were mostly from the private sector in a few districts like Mehsana, Patna and Mumbai. More than one lakh private laboratories are now notifying cases to the government, but many more still need to be brought into the fold of the national programme.

The Indian government is also heavily reliant on insensitive diagnostic tools such as sputum smears that miss nearly 30% to 40% of tuberculosis cases, which could add to the problem of under-diagnosing and, therefore, underreporting.

“Overall, the message for India is very clear – acknowledge the reality, collect better data on true burden of TB, deaths, and drug-resistance, and allocate greater funding to tackle this huge problem,” said Pai.