TB LAMP- a potential way forward to diagnose smear negative suspected TB cases.

OBJECTIVE

Mycobacterium tuberculosis has co-existed with humans for millennia. Even after century from its discovery, TB is currently one of the major health problems globally, especially in developing nations. Tuberculosis diagnostics poses the biggest challenge particularly in peripheral settings in TB endemic countries. Smear microscopy still remains the method of choice for identifying TB; however the need of the hour calls for replacement of this technique, by a rapid diagnostic tool with higher sensitivity and specificity. TB LAMP was approved by WHO in 2016, as substitute for smear microscopy. However more data is required, especially for smear negative suspected TB patients, before its deployment into field setting.

STUDY

DESIGN

A total of 51 smear negative suspected TB patients were enrolled in this study. The patients were clinically/radiological diagnosed with TB. Microbiological confirmation in terms of culture and NAAT based diagnosis by Xpert MTB/RIF and TB LAMP was performed for all the patients.

RESULTS

TB LAMP was found to be positive in 74.50 % samples. The sensitivity of TB LAMP and Xpert MTB/RIF, using culture as reference standard, was found to be 84.85 % (95 %CI: 68.10-94.89 %) and 82.35 % (95CI: 65.47-93.24 %) respectively. The specificity of TB LAMP and Xpert MTB/RIF, using culture as reference standard, was found to be 47.06 % (95 %CI: 22.98-72.19 %) and 41.1 (95CI: 18.44-67.08 %) respectively. The PPV and NPV of TB LAMP was 40.72 % (95 %CI: 30.02-52.38 %) and 87.87 % (95 %CI: 73.67-94.94 %) respectively.

CONCLUSION

We observed similar sensitivity and specificity of TB LAMP and Xpert MIB/RIF for smear negative suspected TB patients. TB LAMP was also able to detect M.tb in 5 % of smear negative, culture negative samples as well. These results indicate that TB LAMP could be a promising candidate of rapid detection of TB in otherwise 'hidden TB' cases. However, further validation is required, before TB LAMP can be introduced to mainstream TB elimination program.