Diagnostic performance of Xpert MTB/RIF in lymph node tuberculosis in a general hospital

In general hospitals, tuberculosis (TB) is an important infectious cause of lymphadenopathy, but its etiological diagnosis rate is very low. This study aimed to determine the performance of Xpert MTB/RIF(Xpert) in differentiate tuberculous lymphadenopathy from other causes.

A retrospective pairing study was carried out from August 2015 to July 2024. A total of 229 participants were involved. Microbiological reference standard (MRS) and composite reference standard (CRS) were used as two standards. All patients underwent biopsy measurement and specimens were examined using histopathology, acid-fast bacilli (AFB), liquid culture with/without Xpert. The baseline information, diagnostic methods and time were compared between two groups. The diagnostic values including sensitivity, specificity, accuracy (ACC), Kappa value and area under the curve (AUC) were compared.

This study included a total of 229 participants, of whom 150 were in the no Xpert group and 79 in the Xpert group. The median age was 44 [31-58] years, with female proportion of 60.0%. The most common sites of lymphadenopathy are the neck (66%), mediastinum (17%), and abdomen (7%). In patients with lymph node tuberculosis (LNTB), MRS was achieved in 35.4% of cases, while 60.0% fulfilled CRS criteria. No significant differences were observed in MRS percentage or pathology positivity rates between the two groups. The median time from biopsy to diagnosis was significantly shorter in the Xpert group compared to the no Xpert group {2 days [interquartile range (IQR), 1-9 days] vs. 7 days (IQR, 5-15 days)}. In comparison to CRS, the sensitivity, specificity and AUC of Xpert were 57.1% [95% confidence interval (CI): 42.2-72.1%], 100%, and 0.786 (95% CI: 0.711-0.861), respectively. The sensitivity of the combined culture and Xpert significantly increased (71.4%, 95% CI: 57.8-85.1%). In comparison to MRS, Xpert shared same sensitivity with culture while specificity was paralleled. The combination of any two procedures yielded better results than single one, with the combined Xpert and pathology yielding 90.0% (95% CI: 83.4-96.6%), combined culture and pathology yielding 87.7% (95% CI: 80.5-94.8%), and combined culture and Xpert yielding 91.7% (95% CI: 80.6-100%).

Xpert can accelerate the microbiological diagnosis time and reduce the misdiagnose of lymph node granulomatous lesions. The application of Xpert combined with culture or pathology may be the best pattern for the diagnosis of LNTB in general hospital.