Retrospective observational study to compare Xpert MTB/RIF assay with other diagnostic tests in lymph node tuberculosis

Background Lymph node tuberculosis (TB) is the most common form of extrapulmonary TB in India. Standards for TB care in India recommend microscopy/culture/CBNAAT/molecular test/histopathology examination and drug sensitivity testing on appropriate specimens from the presumed sites of involvement for all patients with presumptive extrapulmonary TB. Objectives To analyze the utility of Xpert MTB/Rif assay in lymph node TB. Methods All patients who underwent lymph node sampling between July 2014 and June 2017 and for whom Xpert MTB/Rif assay was done were included. Demographic profile, Xpert MTB/Rif assay result, histopathology/cytology findings, smear acid-fast bacillus (AFB), and AFB culture results were noted. A composite reference score (CRS) was made. Results Xpert MTB/Rif assay was positive in 63 of the 81 patients. Xpert had a sensitivity of 82.14% and specificity of 86.18%when compared against AFB culture and 75.61% and 98.97% when compared against CRS. Conclusion Xpert MTB/Rif assay is a valuable test for rapid diagnosis of lymph node TB.