Assessing the performance of a point-of-need diagnostic algorithm in rapid detection of peripheral lymph node tuberculosis (Mobile-TB-Lab): a diagnostic evaluation study protocol.

Background: Early and accurate diagnosis of tuberculosis (TB) is central to ensuring the proper treatment and curbing the transmission of the disease. Despite the significant burden, the diagnosis of peripheral lymph node(LN)TB, the most prevalent form of extra pulmonary tuberculosis (EPTB), has been challenging in low resource settings. To meet the existing needs, the Mobile-TB-Lab study set out to evaluate two innovative approaches, including thermal imaging and recombinase-aided amplification assay (RAA) in Minoo for point-of-need diagnosis of LNTB. The synergy of these index tests is expected to pave the way for rapid detection of EPTB in resource-constrained settings.

Methods: Mobile-TB-Lab is a multicountry diagnostic evaluation study to be performed in Bangladesh and Uganda. Under this protocol, a total of 200 suspected EPTB patients with cervical lymphadenitis will be enrolled from tertiary healthcare facilities in Bangladesh and Uganda. Each participant will be subjected to laboratory investigations including microscopy, real-time PCR, cytology, culture and Xpert MTB/RIF Ultra with the tissue sample following fine-needle aspiration (FNA). As the index tests, thermal imaging will be performed before performing the FNA, and the leftover aspirate will be used to perform RAA in the Minoo device. The diagnostic efficiency of the index tests will be determined against a composite reference standard based on the laboratory methods. Besides, latent class analysis will be performed to assess the diagnostic accuracy of the index tests. Finally, health economic evaluation will be performed to determine the cost-effectiveness of the investigative methods. Background: The study protocol (PR-23031) has been approved by the research review committee (RRC) and the ethical review committee (ERC) under the institutional review board (IRB) of icddr,b in Bangladesh. In Uganda, the study protocol has been approved by the Research Ethics Committee of the Infectious Diseases Institute of Makerere University under reference number IDI-REC-2023-62 and approval from the Uganda National Council for Science and Technology (UNCST) under reference number HS3494ES. All the study materials and procedures to be used for the enrolment of the participants have been approved by the ethical review committee. The study will be performed according to the declaration of Helsinki and the International Council for Harmonisation-Good Clinical Practice to ensure the participants' rights, safety and well-being. The findings from this study will be submitted to peer-reviewed journals and presented at relevant national and international meetings.