Proportion of Microbiologically Confirmed Extrapulmonary Tuberculosis among Pathologically diagnosed Extrapulmonary Tuberculosis

A BSTRACT Context: Current National Tuberculosis Elimination Program (NTEP) guidelines recommends culture/CBNAAT/molecular test/histopathology examination and drug sensitivity testing for all patients with presumptive Extrapulmonary TB (EPTB). Studies on correlation of CBNAAT with pathological evidence in the diagnosis of EPTB are scarce in our literature. Aims: To estimate the proportion of microbiologically confirmed EP TB among the cases with pathological evidence and among those who underwent molecular testing; and to estimate the proportion of EP TB notified who underwent either pathology evaluation (FNAC or Biopsy) or microbiology evaluation (NAAT / Culture) Settings and Design: Record based cross sectional study. Material and Methods: Data of EPTB patients registered for treatment from January to December 2022 were collected and triangulated to see what proportion of patients diagnosed / notified in one source can be traced in the other department, and verified report at that department. Statistical analysis used: Proportions were estimated for the tests undergone and the diagnostic yield of each test. Results: Among 282 study subjects, 62 (21.98%) cases were microbiologically confirmed. In 118 (41.84%) patients, cytopathology/histopathology was the basis of diagnosis. 26% of pathologically diagnosed TB had a positive CBNAAT. Yield of NAAT positivity among patients who underwent CBNAAT testing was 52% with high yield of 78% in lymph node TB. For 87 (30.85%) patients, neither microbiological confirmation nor histopathology/cytological evidence was available. Conclusions: Though CBNAAT is integral part of TB diagnosis, only 47% underwent NAAT examination. Whenever NAAT was done, the yield was reasonable (52%).