Performance of the Roche cobas MTB Assay for the Molecular Diagnosis of Pulmonary Tuberculosis in a High HIV Burden Setting

Abstract

Disclosures: L.S. reports having a patent issued (USP 8709712) that relates to quality control material and program for molecular TB diagnostics quality management. Roche Molecular Solutions provided funding but did not have any input in the study design or presentation of results contained in the article.

Evaluation of the Roche cobas MTB and MTB-RIF/INH Assays in Samples from Germany and Sierra Leone

“…Our study demonstrates that the cobas MTB assay meets the minimal performance characteristics stated in the WHO target product profile for a same-day diagnostic test detecting pulmonary TB as an alternative to smear microscopy, which is a sensitivity of >80% (smear-negative samples, >60%; smear-positive samples, 99%) and a specificity of >98% compared with culture ( 22 ). We observed that the overall sensitivity of cobas MTB (89.2%; 95% CI, 81.7 to 93.9%) was lower than in a study by Scott et al, who reported an overall sensitivity of 94.7% (95% CI, 88.1 to 98.3%) using decontaminated sputum sediments from individuals with presumptive or confirmed TB in South Africa ( 16 ). However, the proportion of smear-negative, culture-positive samples in our study was significantly larger (26.5% versus 7%) ( 16 ).…”

“…MTBC DNA-positive samples are subsequently tested for resistance-associated mutations, which allows for diagnosis of RIF or INH monoresistance as well as MDR-TB. Limited data are available for the performance of the cobas MTB and MTB-RIF/INH assays compared to culture and other commercially available NAATs ( 16 , 17 ).…”

“…5% versus 7%)(16). In addition, Scott et al reported a sensitivity of 81.8% (95% CI 59.7-94.8%) for cobas MTB in smear-negative samples compared to 63.0% (95% CI 44.2-78.5%) in this study, which is likely a reflection of a lower bacterial burden even among smear-negative patients in Germany compared to smear-negative patients in South Africa(16).Both sensitivity and specificity of the cobas MTB assay for detection of MTBC DNA in clinical samples were comparable to or superior to that of five other platforms mentioned in the "WHO consolidated guidelines on tuberculosis (Module 3: Diagnosis)" (11). Therein, performance data were reported for Xpert MTB/RIF, Xpert MTB/RIF Ultra, Truenat TM MTB and Truenat TM MTB plus (Molbio Diagnostics India), and a loop-mediated isothermal amplification assay, with overall sensitivities and specificities ranging from 73-90% and 96-98%, respectively (11).…”

Comparative Analytical Evaluation of Four Centralized Platforms for the Detection of Mycobacterium tuberculosis Complex and Resistance to Rifampicin and Isoniazid

“…A study in South Africa, in a high-HIV-burden setting, also reported that the Roche cobas MTB, Abbott RealTi m e MTB, and Xpert MTB/RIF assays ( n = 294) have similar performances of 94.7% (95% CI, 88% to 98%), 92.6% (95% CI, 85% to 97%), and 91.6% (95% CI, 84% to 96%), respectively. These assays also performed similarly among smear-negative, culture-positive individuals ( n = 221): 81.8% (95% CI, 60% to 95%), 72.7% (50% to 89%), and 72.7% (50% to 89%), respectively ( 11 ).…”

“…Published data from clinical studies to date demonstrate promising diagnostic performances of these assays when used in the appropriate scenarios ( 8 – 11 ). However, most of the available studies have important limitations.…”