Blood transcriptomic signatures for symptomatic TB in an African multi-cohort study.

Abstract

Multiple host blood transcriptional signatures have been developed as non-sputum triage tests for tuberculosis (TB). We aimed to compare the diagnostic performance of 20 blood transcriptomic TB signatures for differentiating between symptomatic patients who have TB versus other respiratory diseases (ORD). As part of a nested case-control study, individuals presenting with respiratory symptoms at primary health care clinics in Ethiopia, Malawi, Namibia, Uganda, South Africa, and The Gambia were enrolled. TB was diagnosed based on clinical, microbiological, and radiological findings. Transcriptomic signatures were measured in whole blood using microfluidic RT-qPCR. Diagnostic performance was benchmarked against the WHO Target Product Profile (TPP) for a non-sputum TB triage test. Among 541 participants, 158 had definite, microbiologically-confirmed TB, 32 had probable TB, while 389 participants had ORD. Nine signatures differentiated between ORD and TB with equivalent performance (Satproedprai7: area under the curve 0.83 [95% CI 0.79-0.87], Jacobsen3: 0.83 [0.79-0.86]; Suliman2: 0.82 [0.78-0.86]; Roe1: 0.82 [0.78-0.86]; Kaforou22: 0.82 [0.78-0.86]; Sambarey10: 0.81 [0.77-0.85]; Duffy9: 0.81 [0.76-0.86]; Gliddon3: 0.8 [0.75-0.85]; and Suliman4 0.79 [0.75-0.84]. Benchmarked against a 90% sensitivity, these signatures achieved specificities between 44% (95% CI 38-49) and 54% (49-59), not meeting the TPP criteria. Signature scores significantly varied by HIV status and country. In country-specific analyses several signatures, such as Satproedprai7 and Penn-Nicholson6, met the minimal TPP criteria for a triage test in Ethiopia, Malawi, and South Africa. No signatures met the TPP criteria in a pooled analysis of all countries, but several signatures met the minimum criteria for a non-sputum TB triage test in some countries.