Comparing Additionality of Tuberculosis Cases Using GeneXpert or Smear-Based Active TB Case-Finding Strategies among Social Contacts of Index Cases in Nepal

This study compares the yield and additionality of community-based active tuberculosis
(TB) active case-finding strategies using either smear microscopy or GeneXpert as the TB diagnostic
test. Active case-finding strategies screened social contacts of index cases and high-risk groups in
four districts of Nepal in July 2017–2019. Two districts (Chitwan and Dhanusha) applied GeneXpert
testing and two districts (Makwanpur and Mahotarri) used smear microscopy. Two control districts
implemented standard national TB program activities. Districts implementing GeneXpert testing
screened 23,657 people for TB, tested 17,114 and diagnosed 764 TB cases, producing a yield of 4.5%.
Districts implementing smear microscopy screened 19,961 people for TB, tested 13,285 and diagnosed
437 cases, producing a yield of 3.3%. The screening numbers required were 31 for GeneXpert and
45.7 for smear districts. The test numbers required were 22.4 and 30.4 for GeneXpert and smear.
Using the TB REACH additionality method, social contact tracing for TB through GeneXpert testing
contributed to a 20% (3958/3322) increase in district-level TB notifications, smear microscopy 12.4%
(3146/2798), and 0.5% (2553/2566) for control districts. Therefore, social contact tracing of TB
index cases using GeneXpert testing should be implemented throughout Nepal within the TB FREE
initiative to close the notification gap and accelerate progress toward END TB strategy targets.

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