Field evaluation of GeneXpert^® (Cepheid) HCV performance for RNA quantification in a genotype 1 and 6 predominant patient population in Cambodia

Abstract

GeneXpert (Cepheid) is the only WHO prequalified platform for hepatitis C virus (HCV) nucleic acid amplification testing that is suitable for point-of-care use in resource-limited contexts. However, its application is constrained by the lack of evidence on genotype 6 (GT6) HCV. We evaluated its field performance among a patient population in Cambodia predominantly infected with GT6. Between August and September 2017, we tested plasma samples obtained from consenting patients at Médecins Sans Frontières' HCV clinic at Preah Kossamak Hospital for HCV viral load (VL) using GeneXpert and compared its results to those obtained using COBAS AmpliPrep/Cobas TaqMan HCV Quantitative Test, v2.0 (Roche) at the Institut Pasteur du Cambodge. Among 769 patients, 77% of the seropositive patients (n = 454/590) had detectable and quantifiable VL using Roche and 43% (n = 195/454) were GT6. The sensitivity and specificity of GeneXpert against Roche were 100% (95% CI 99.2, 100.0) and 98.5% (95% CI 94.8, 99.8). The mean VL difference was -0.01 (95% CI -0.05, 0.02) log IU/mL for 454 samples quantifiable on Roche and -0.07 (95% CI -0.12, -0.02) log IU/mL for GT6 (n = 195). The limit of agreement (LOA) was -0.76 to 0.73 log IU/mL for all GTs and -0.76 to 0.62 log IU/mL for GT6. Twenty-nine GeneXpert results were outside the LOA. Frequency of error and the median turnaround time (TAT) for GeneXpert were 1% and 0 days (4 days using Roche). We demonstrated that the GeneXpert HCV assay has good sensitivity, specificity, quantitative agreement, and TAT in a real-world, resource-limited clinical setting among GT6 HCV patients.

In‐field evaluation of Xpert® HCV viral load Fingerstick assay in people who inject drugs in Tanzania

“…Existing literature evaluating the performance of the Xpert ® HCV VL assay in Cambodia has provided compelling evidence to support its use in such resource‐limited settings . However, this study was conducted using plasma, which still requires a laboratory set up for plasma separation.…”

“…Existing literature evaluating the performance of the Xpert ® HCV VL assay in Cambodia has provided compelling evidence to support its use in such resource-limited settings. 24 However, this study was conducted using plasma, which still requires a laboratory set up for plasma separation. Our study adds to the limited literature addressing the use of HCV NAT point-of-care tests in sub-Saharan Africa, raising the potential for Xpert ® HCV VL Fingerstick assay to provide a further simplified solution to existing issues related to HCV diagnosis.…”

Improving linkage to care of hepatitis C: Evaluation of GeneXpert® HCV Viral Load Point-of-Care Assay in Indonesia

“…The negative bias at the lower end is likely due to sparse data in the range of 10 th to 25 th percentiles, while data for higher VL across the range 50 th to 75 th percentiles is more equally distributed and therefore the regression curve is less driven by the high-end samples. [25,30,37,39]. This could be attributable to smaller number of samples, particularly in the range of lower VL values [40,41].…”

“…Newly installed GeneXpert devices, together with those that have been placed by Tuberculosis program, are integrated to support HCV scale-up program in Indonesia [27]. Given the presence of various HCV genotypes/subgenotypes (genotypes 1, 2, 3, 4, 6, and mix genotypes) in Indonesia which may implicate the reliability of HCV RNA quantification [28,29], assessment of this system is needed prior to using for confirmation of viremic infection and monitoring of HCV treatment [7,16,30]. This study aimed to evaluate the performance of the Xpert® HCV Viral Load and compared it with the FDA-approved Roche Cobas® TaqMan® HCV Test, v2.0 [31] using Indonesian HCV-samples with various genotypes.…”

Significant Improvement in Diagnosis of Hepatitis C Virus Infection by a One-Step Strategy in a Central Laboratory: an Optimal Tool for Hepatitis C Elimination?

“…An example of an alternative sampling has been described by Lazarus et al, who implemented a one-step diagnosis strategy using whole blood sampled on dried blood spots (18). In this regard, the use of the GenXpert platform (Cepheid, Sunnyvale, CA, USA), which has shown an extremely optimal correlation with highthroughput systems (19,20), represents an adequate alternative for HCV viral load determination when it is not possible to perform it in a central laboratory. This is the case of special populations like, for instance, active intravenous drug users, in which it seems advisable to conduct any viral load testing at the same center and start antiviral treatment as soon as possible.…”