Patients with silicosis are 4 times more likely to get TB, says ICMR

NEW DELHI: India doesn’t have a separate national health programme for silicosis, even though most patients suffering from the fibrotic lung disease, caused by inhaling tiny silica dust, are three to four times more likely to get tuberculosis, said an ICMR study.

The study, published in the Nature journal, said that if India wants to meet the global target of eliminating the two lung diseases by 2030, it needs to integrate silicosis control efforts with the TB control programme.

It also said silicosis was associated with treatment failure and death due to TB, with a higher rate of treatment discontinuation among silico-tuberculosis patients than TB patients without silicosis. 

Recommending a national silicosis elimination program at the block level through multi-sector engagement, the study said the government must monitor its implementation to meet its 2030 target.

India has set an ambitious target of eliminating tuberculosis by 2025, five years ahead of the global Sustainable Development Goal (SDG) target of 2030. 

“Tuberculosis (TB) is one of the most prevalent diseases among patients with silicosis. Patients with silicosis are three to four times more likely to get TB than those who do not have silicosis,” said Dr Mihir P Rupani, Scientist E, Indian Council of Medical Research (ICMR)-National Institute of Occupational Health (NIOH), the author of the study.

Patients with both silicosis and TB are given the combined diagnosis of silico-tuberculosis, the true burden of which is unknown mainly due to a lack of surveillance and insufficient healthcare access, Dr Rupani told this newspaper.

The study found that patients with silico-tuberculosis had six times higher odds of experiencing relapses of TB, four times higher odds of developing drug-resistant TB, three times higher odds of death due to TB, and five times higher odds of treatment failure as compared to TB patients without silicosis.

It suggested that all patients with silicosis should be screened for TB and treated according to national TB program guidelines, while all patients with TB who have a history of occupational dust exposure should be evaluated for silicosis and provided appropriate pulmonary/vocational rehabilitation, it added. 

“We need a national health program in India for silicosis,” he said. Currently, chest X-rays or high-resolution computed tomography (HRCT) are used to confirm the diagnosis.

The study also suggested that in India, X-ray facilities, particularly with high-resolution digital films, should be expanded throughout block levels to aid in the early detection of silicosis. 

He said silicosis afflicts thousands of workers in hazardous occupations, but it is still underreported in India. 

It is estimated that over 12.9 thousand deaths globally occurred due to silicosis, a lung disease caused by breathing in tiny bits of silica, a common mineral found in sand, quartz and many other types of rock, with an estimated 0.65 million disability-adjusted life years (DALYs) in 2019. 

Silicosis mainly affects workers exposed to silica dust in jobs such as construction and mining. 

For the study, Dr Rupani conducted a retrospective cohort study evaluating TB treatment outcomes in Khambhat block, in Gujarat, between 138 patients with silico-tuberculosis and 2,610 TB patients without silicosis.

“The lack of a cure for silicosis, diagnostic challenges in distinguishing the two diseases even on radiography, and facilitating early detection of cases called for the need for collaborative TB-silicosis activities. Early detection of silicosis and TB among silica-exposed workers has been recommended to prevent further lung damage and limit the spread of TB in the community,” Dr Rupani added.