A prospective multicentre diagnostic accuracy study for the Truenat tuberculosis assays

Abstract

BackgroundBringing reliable and accurate tuberculosis (TB) diagnosis closer to patients is a key priority for global TB control. Molbio Diagnostics have developed the Truenat point-of-care molecular assays for detection of TB and rifampicin (RIF) resistance.MethodsWe conducted a prospective multicentre diagnostic accuracy study at 19 primary health care centres and seven reference laboratories in Peru, India, Ethiopia and Papua New Guinea to estimate the diagnostic accuracy of the point-of-care Truenat MTB, MTB Plus and MTB-RIF Dx assays for pulmonary TB using culture and phenotypic drug susceptibility testing as the reference standard, compared to Xpert MTB/RIF or Ultra.ResultsOf 1807 enrolled participants with TB signs/symptoms, 24% were culture positive for Mycobacterium tuberculosis, of which 15% were RIF-resistant. In microscopy centres, the pooled sensitivity of Truenat MTB and Truenat MTB Plus was 73% [95% CI: 67, 78] and 80% [95% CI: 75, 84], respectively. Among smear-negative specimens, sensitivities were 36% [95% CI: 27, 47] and 47% [95% CI: 37, 58], respectively. Sensitivity of Truenat MTB-RIF was 84% [95% CI: 62, 95]. Truenat assays showed high specificity. Head-to-head comparison in the central reference laboratories suggested that the Truenat assays have similar performance to Xpert MTB/RIF.ConclusionWe found performance of Molbio's Truenat MTB, MTB plus and MTB-RIF Dx assays to be comparable to that of the Xpert MTB/RIF assay. Performing the Truenat tests in primary health care centres with very limited infrastructure was feasible. These data supported the development of a WHO policy recommendation of the Molbio assays.

Diagnostic Accuracy of the Truenat MTB Plus Assay and Comparison with the Xpert MTB/RIF Assay to Detect Tuberculosis among Hospital Outpatients in Cameroon

“…In 2020, the WHO recommended the TrueNat MTB or MTB Plus assay as the initial diagnostic test for TB rather than smear microscopy/culture, along with the Truenat MTB-RIF Dx for detection of rifampin resistance in people with a positive Truenat MTB or MTB Plus result ( 17 ). This recommendation followed a multicenter evaluation of the Truenat assays conducted by the Foundation for Innovative New Diagnostics (FIND) at seven sites in four countries ( 18 ). The WHO has highlighted the need for additional evaluations of the diagnostic accuracy of these assays in a variety of settings and populations, including for people living with HIV, to inform future recommendations ( 6 ).…”

Diagnostic Advances in Childhood Tuberculosis—Improving Specimen Collection and Yield of Microbiological Diagnosis for Intrathoracic Tuberculosis

“…Genotypic tests predict resistance to a drug by detecting resistance-associated mutations rather than establishing in vitro susceptibility. Xpert can detect mutations in the rpo B gene involved in more than 95% of RIF resistance with a sensitivity of 99% and the Truenat MTB-RIF assay has shown a sensitivity of 84% in adults [45,46]. The WHO has also endorsed line probe assays (LPAs) which use different molecular technology to detect mutations associated with resistance [47].…”

Towards Accurate Point-of-Care Tests for Tuberculosis in Children

“…So far, all studies evaluating these assays were performed in India, with some including head-to-head comparisons between Xpert MTB/RIF and Truenat MTB indicating both assays had similar performance characteristics [ 38 ]. A large multi-center study led by FIND, which included 1807 adult participants with suspected pulmonary TB from study sites in India, Peru, Ethiopia and Papua New Guinea, published its results recently, reporting overall pooled sensitivity estimates of 73% and 80% for the Truenat MTB and the Truenat MTB Plus assay, respectively [ 39 ]. However, the sensitivity of both assays was far lower in smear-negative, culture-positive participants (36% and 47%, respectively), which raises concerns regarding their performance in children, who typically have paucibacillary TB disease.…”