Accuracy on Diagnostic Performance of Point Of Care Liodetect® Tb-St Rapid Test for the Diagnosis of Pulmonary Tuberculosis in North West Ethiopia

Background: Tuberculosis (TB) is the leading cause of death due to a single infectious agent. To improve TB case detection and treatment in healthcare-disrupted urban and rural settings, an accurate point-of-care (POC) test that does not rely on sputum quality is urgently needed.

Objective: To evaluate the accuracy of performance of a new rapid POC antibody-based detection test for the diagnosis of pulmonary TB.

Methods: This prospective cross-sectional study was conducted from June 2018 to July 2019 in presumptive pulmonary TB (PTB) patients in Northwest Ethiopia. Sputum was routinely collected for diagnosis of TB with a Lowenstein Jensen (LJ) culture and an Xpert MTB/RIF test was compared with the LIODetect TB ST rapid point-of-care diagnostic test. Using LJ culture and Xpert MTB/RIF for M.tb detection as our reference standards. SPSS ver. 20 and Medcalc were used to analyze descriptive and diagnostic accuracy tests, respectively.

Result: A total of 233 samples were analyzed.  The LIODetect TB-ST rapid test showed a sensitivity of 53.0%, specificity of 91.0%, positive predictive values (PPV) of 70.0 %, negative predicted values (NPV) of 83.1 % with overall accuracy of 80.3%when compared to the LJ culture as a reference method. Similarly, the same test showed sensitivity of 69.6%, specificity of 90.6%, PPV of 67.9%, NPV of 91.1%, and over all accuracy of 85.8% when compared to the Xpert MTB/RIF as a reference standard. Further, when exclusively evaluated in people living with HIV (PLWH), the LIODetect TB-ST rapid test diagnostic showed similar performance as  described above, with an overall accuracy of 83.7% and 86.1% when compared to LJ culture and the Xpert MTB/RIF test, respectively.

Conclusion: The LIODetect TB-ST rapid test performance was optimal against the MTB/RIF test and LJ culture. This POC test also had optimal sensitivity and better specificity in both HIV negative people and People living with human immunodeficiency virus (PLWH). Thus, the LIODetect TB-ST rapid test could be a useful  as POC TB screening test in resource-limited urban/rural areas, where routine TB diagnosis using LJ and/or the Xpert MTB/RIF test can not be performed.