Laboratory Cost Analysis of Conventional and Newer Molecular Tests for Diagnosis of Presumptive Multidrug-Resistant Tuberculosis Patients.

Introduction: Tuberculosis (TB) remains a deadliest infectious disease. Lack of rapid test with low cost is one of the important challenges to eradicate the TB. The objective of the study was to analyze the laboratory costs of conventional and newer molecular tests, for diagnosis of presumptive multidrug-resistant TB (MDR-TB) patients.

Methods: A detailed laboratory cost of various conventional tests (Ziehl - Neelsen [ZN] microscopy, light-emitting diode-fluorescent microscopy [LED-FM], culture and drug susceptibility testing [DST] using solid Lowenstein-Jensen media and liquid media [BACTEC MGIT 960]) was compared with rapid methods (GenoType MTBDRplus line probe assay [LPA] and GeneXpert MTB/RIF assay). Laboratory cost was also calculated in terms of cost per TB and MDR-TB case detected by using different diagnostic scenarios.

Results: Cost per test for ZN microscopy, LED-FM, LPA, GeneXpert MTB/RIF assay, solid culture plus DST, liquid culture plus DST was found as $2.5 (INR 156.8), $2.0 (INR128.9), $18.6 (INR1210), $13.8 (INR 895.2), $21.5 (INR 1396.6), and $29.1 (INR 1888.2), respectively. The laboratory cost for detecting TB and MDR-TB by diagnostic scenarios involving molecular DST was found to be less as compared to involving only conventional liquid culture-based test.

Conclusions: The implementation of rapid molecular tests with selective use of liquid culture-based DST may be less in cost as compared to the use of culture-based DST alone, at high burden reference TB laboratory.