GeneXpert can provide results in just two hours and identify resistance to rifampicin drug

Providing accurate diagnosis for TB and thereby enabling earlier initiation of treatment has got a big boost. Currently, around 30 private laboratories across the country have come together to provide the WHO-approved GeneXpert MTB/RIF molecular test to diagnose active TB at a subsidised ceiling price of Rs.1,700 and Hain Genotype test at a ceiling price of Rs.1,600. More labs are expected to join the initiative.

“Laboratories can charge less than the ceiling price but not more,” explained Dr. Navin Dang, Director of Dr. Dang’s Lab Pvt Ltd, New Delhi. He is one of the eight Governing Council members of the Initiative. His lab started offering the GeneXpert test on March 26 and charges Rs.1,500. According to him, the market price of the molecular test is more than Rs.3,500.

Another WHO-approved test that will soon be available at a subsidised ceiling price is the MGIT Liquid Culture (the ceiling price yet to be decided). The Hain Genotype and MGIT Liquid Culture will help in deciding which alternative drugs should be given to patients who are resistant to first-line TB drugs.

Any private laboratory can become a member of the initiative and offer the test at a subsidised rate provided it is accredited either by the National Accreditation Board for Laboratories (NABL) or College of American Pathologists (CAP) or by the Revised National TB Control Programme (RNTCP). According to the Charter, the Governing Council can “examine and recommend exemption [for laboratories] from this eligibility criterion on a case-by-case basis.”

What has been the government’s role? “Zero...this is totally a private-sector initiative,” Dr. Dang stressed.

One of the biggest positive outcomes will be that the member labs will be obliged never to provide the inaccurate and unreliable serological (blood) antibody tests for diagnosing active TB. “Any laboratory that wants to become a member of the Initiative should abide to ban serological test and subject itself to quality assurance by an external agency,” said Dr. Nalini Krishnan, one of the Governing Council members. She is also the Director of the Chennai-based REACH.

The implication of this decision is huge — the private sector in India offers this unreliable blood test to at least 1.5 million people every year, according to a 2011 paper in The Lancet. A serological test costs Rs.2,500 to Rs.3,000.

The consequences of relying on blood tests are terrible — patients who are actually not suffering from active TB are put on long-term medication, while many people who are actually suffering from active TB never end up getting the treatment at the right time. TB patients who are not undergoing treatment can spread the disease to a large number of people.

It is for this reason that the government banned the serological TB test in June last year. Yet, many private laboratories continue to provide the test.

For instance, a couple of major laboratories in Chennai continue to offer blood tests for diagnosing TB.

The GeneXpert test, on the other hand, has 98 per cent sensitivity (ability to detect every positive TB case) in smear-positive cases. And specificity (ability to correctly diagnose only the positive cases) is 99 per cent. The molecular test can provide reliable results in just about two hours.

But the biggest advantage is its ability to identify rifampicin drug resistance. Rifampicin is one of the first-line drugs given to TB patients. And patients who are resistant to the drug are generally resistant to isoniazid drug (another first-line drug) too. Hence, the molecular test can serve as an excellent marker of multidrug-resistant TB (MDR-TB).

According to a paper in the Health Policy and Planningjournal, “MDR-TB is 1-3 per cent among fresh pulmonary cases … and 13-17 per cent among previously treated cases” in India.

The participating laboratories are also required to provide clinical advice to patients who test positive for active TB.

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