To Compare Result of CBNAAT With Line Probe Assay for Detection of Rifampicin Monoresistant Mycobacterium Tuberculosis.

Abstract

Background&Method: The study was carried out in the department of Respiratory
Medicine in Index Medical College, Indore with an aim to compare result of CBNAAT with
Line Probe Assay for detection of Rifampicin monoresistant mycobacterium tuberculosis. All
patients >14 years of age admitted in Chest ward of Index Medical College, Indore with
features of TB between May 2020 to April 2021. Study was conducted on 50 patients from
the Department of TB and CHEST at Index Medical College, Research centre and Hospital,
Indore and sample was sent to Intermediate Reference Laboratory, M.R.T.B.
Hospital/Chest Centre, Indore and all the tests was performed with due permission from the
Institutional Ethical Committee and informed consent from the subjects or their legal
relatives.
Result:The Rifampicin resistance by CBNAAT test. This test shows that on CBNAAT test
out of 50 participants 33 were tested positive and 17 were tested negative. The Rifampicin
resistance by LPA test. This test shows that on LPA test out of 50 participants 35 were tested
positive and 15 were negative. The above table depicts the sensitivity of CBNAAT/Xpert
MTB/Rif Assay and Line Probe Assay as 91.4% (CI= 76.9%-98.2%) and 96.9% (CI= 84.2%-
99.9%) respectively, while the specificity of both the tests were 93% (CI= 68%-99.8%) and
82.3% (CI=56.7%-96.2%) respectively. Positive predictive value and negative predictive
value of CBNAAT are 96.9% and 82.3% respectively while that of LPA are 91.4% and 93%
respectively.
Conclusion:According to the present study, as compared to CBNAAT, LPA detects 96.9%
of true positives i.e. those who truly have Rifampicin resistance. The test has accuracy of
92%. Accordingly, the positive predictive value of LPA is 91.4% implying that 91.4% of
subjects actually have Rifampicin resistance tuberculosis given that the subjects have a
positive test results for rifampicin resistance.