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Current Affairs

Truenat: High accuracy TB diagnostic test

Date: 17 January 2020 Tags: Miscellaneous

Issue

The World Health Organization (WHO) had mentioned that the India-made Truenat MTB, a molecular diagnostic test for pulmonary and extrapulmonary TB and rifampicin-resistant TB, has high accuracy.

 

Background

Truenat is developed by the Goa-based Molbio Diagnostics. The company was provided with technical assistance and resources by the Foundation for Innovative New Diagnostics (FIND) to help commercialise Truenat. 

 

Details

  • Truenat will be cheaper per test than Xpert. The equipment and cartridges cost more in the case of Xpert. Truenat is robust and most suited for Indian conditions.

  • While sputum microscopy has only about 50% sensitivity, Truenat has been found to have higher sensitivity and specificity.

  • The overall sensitivity of the Truenat MTB assay is 83% and specificity is 99%. In the case of Truenat MTBPlus, which uses two targets to diagnose TB bacteria, the sensitivity increases to 89% and the specificity is 98%.

  • In comparison, Xpert, which is also a molecular diagnostic test and has been widely used across the world, the sensitivity is 85% and specificity is 98%.

  • In cases where the sample is found to be positive, tests can be done to know if the TB bacteria are already resistant to rifampicin, a drug used as part of first-line treatment.

  • Truenat MTB-RIF test for knowing the resistance has 93% sensitivity and 95% specificity.

Advantages of Truenat

  • While Xpert needs reliable electricity supply and air-conditioning, Truenat is battery operated and portable, hence, it can be used in remote places. Truenat takes about 25 minutes to extract the DNA and another 35 minutes for diagnosis. Testing for rifampicin resistance takes an hour and is done only if the sample tests positive for TB.

  • In the case of Xpert, it takes two hours to complete the diagnosis and test for rifampicin resistance.

  • Only when samples test positive will the test for rifampicin resistance be carried out in the case of Truenat. This is unlike Xpert where both TB diagnosis and rifampicin resistance test are done in one go.

  • Hence the use of reagents may be reduced and will help make the testing cheaper when Truenat is used.