NEW DELHI: Blood tests, commonly used in India to detect tuberculosis (TB), have been banned.

The Union health ministry has banned the import of sero–diagnostic kits, saying it is giving inconsistent and imprecise results leading to wrong diagnosis of the deadly air–borne disease.

The official gazette notification says, "Their use is likely to involve risk to human beings", and safer alternatives are available. Experts say these blood tests more often test positive when the patient does not have TB (false positive) and test negative when the patient actually has TB (false negative).

The World Health Organization, in its first–ever negative policy recommendation, recently called on governments to immediately ban blood tests prescribed and used to detect TB, mainly in the private sector.

Despite the evidence against blood tests to detect TB, experts say 15 lakh TB serological tests are estimated to be done in India, with patients spending an estimated Rs 75 crore ($15 million) annually on such tests.

Joint secretary in the ministry Arun Panda says in the notification, "In exercise of the powers conferred by section 10A of the Drugs and Cosmetics Act, 1940, the Central government hereby makes the following amendment."

An expert group, set up by the Drug Controller General of India, had found that blood tests are mostly inaccurate for TB detection. A ministry official said, "The DCGI had set up an eight-member committee to look at whether a proposal by the WHO of banning blood tests for TB was accurate and whether these kits can be trusted. The committee has said it is not advisable to use blood tests and hence should be banned."

Experts say not only do these blood tests fail to accurately diagnose TB, bit they are also not even cost- effective as compared to the standard culture test provided free by the government.

Dr Sarman Singh, who heads the microbiology department at AIIMS, had said, "Inaccurate blood tests are rampant for TB diagnosis in India. It is also expensive: over Rs 4,000 for the three blood tests. Inaccurate test results are making patients, who are TB-free go through unnecessary treatment, while others are not even being offered treatment because the tests show they are TB negative when they are actually positive."

A published study in 2010 estimated that in India $47.5 million (out of patients' pockets) are spent on serological tests, most of which miss many TB cases.

With the disease infecting an estimated 2.3 million people in 2010 alone and killing 3.6 lakh — nearly 1,000 deaths per day with one in six deaths being those aged between 15 and 49, early and effective diagnostics is of vital importance for India.

Dr Ashok Kumar, head of India's revised national TB control programme, said none of the serological tests available in the market "have published evidence to support their claims of sensitivity and specificity usually in excess of 95% each, according to package inserts. They provide no quality assurance and tests from different labs on specimens from the same patient often yield widely varying results."

Experts say most of these ELISA kits are imported from France and the UK. However, these countries themselves do not approve the same tests for clinical use on their own TB patients.

Dr V M Katoch, who is the chief of the Indian Council of Medical Research, said there are more than 73 manufactures of TB serological test kits. There are at least 24 TB rapid test kit manufactures from China alone, followed by the USA. India has eight rapid test manufacturers.

"The claims of every manufacturer are extremely tall and misguiding. All Indian manufacturers have claimed high accuracy. Indeed, all these claims are based on in-house or small studies with no proper validation. Sensitivity or ability to diagnose true TB cases is very critical and any test which has lesser detection rate than sputum microscopy does not warrant serious attention," Dr Singh and Dr Katoch said.