Elsevier

Journal of Clinical Virology

Volume 88, March 2017, Pages 46-51
Journal of Clinical Virology

Point -of -care testing (POCT) in molecular diagnostics: Performance evaluation of GeneXpert HCV RNA test in diagnosing and monitoring of HCV infection

https://doi.org/10.1016/j.jcv.2017.01.006Get rights and content

Highlights

  • •

    Xpert HCV RNA assay correlates well with Abbott HCV RNA assay in terms of viral load estimation in HCV infected patients.

  • •

    Xpert HCV RNA assay can be a useful point of care of diagnostic tool for its use in peripheral health settings.

Abstract

Background

Molecular testing at the point-of-care may turn out to be game changer for HCV diagnosis and treatment monitoring, through increased sensitivity, reduced turnaround time, and ease of performance. One such assay GeneXpert® has recently been released.

Objectives

Comparative analysis between performances of GeneXpert® and Abbott HCV-RNA was done.

Study design

174 HCV infected patients were recruited and, one time plasma samples from 154 patients and repeated samples from 20 patients, obtained at specific treatment time-points (0, 4, 12 and 24) weeks were serially re-tested on Xpert®.

Results

Genotype 3 was the commonest, seen in 80 (66%) of the cases, genotype 1 in 34 (28.3%), genotype 4 in 4 (3.3%) and genotypes 2 and 5 in 1 (0.8%) each. Median HCV RNA load was 4.69 log10 (range: 0–6.98 log10) IU/ml. Overall a very good correlation was seen between the two assays (R2 = 0.985), concordance of the results between the assays was seen in 138 samples (89.6%). High and low positive standards were tested ten times on Xpert® to evaluate the precision and the coefficient of variation was 0.01 for HPC and 0.07 for the LPC. Monitoring of patients on two different regimes of treatment, pegylated interferon plus ribavirin and sofosbuvir plus ribavirin was done by both the systems at baseline, 4, 12 and 24 weeks. Perfect correlation between the assays in the course of therapy at different treatment time- point in genotypes 3 and 1 was seen.

Conclusion

The study demonstrates excellent performance of the Xpert® HCV assay in viral load assessment and in treatment course monitoring consistency.

Section snippets

Background

HCV infection is a major public health problem and is associated with significant liver-related morbidity and mortality globally [1], [2]. People with untreated HCV infection are at increased risk of liver cirrhosis, hepatocellular carcinoma, and liver failure [3]. Owing to the attributes of HCV which make it a likely candidate for elimination [4], world health organisation (WHO) in 2012, has launched its global action framework for elimination of hepatitis C in near future by increasing

Objectives

The aim of this study was to evaluate the performance of the Xpert® HCV for viral load estimation and monitoring of patients on antivirals and to compare it with the FDA approved Abbott Real Time HCV quantitative assay (Abbott, Weisbaden, Germany).

Subjects and samples

This was a prospective study conducted in the Department of Clinical Virology, Institute of Liver and Biliary Sciences (ILBS), a tertiary care liver centre. Overall, 174 consecutive anti-HCV antibody positive patients between July–December 2015 either coming to the outpatient department or admitted in the hospital were recruited in this study. Informed consent was taken from the participants. Patients with co-infection with HBV or HIV, patients with low serum/cut-off (S/Co) ratio (≥1 to <4) on

Results

Of the 174 subjects recruited in the study, male preponderance was seen with M:F ratio of 1.3:1. Genotyping could be done in 120 samples with detectable viral load more than 3 log IU/ml. Genotype 3 was the commonest, seen in 80 (66%) of the cases, followed by genotype 1 in 34 (28.3%), genotype 4 in 4 (3.3%) and genotypes 2 and 5 in 1 (0.8%) each (Table 1). HCV RNA load in the samples ranged from 0 to 6.98 log10 IU/ml, with a median value of 4.69 log10 IU/ml.

Discussion

In this study, we evaluated the performance characteristics of the recently launched Xpert assay which is a point-of-care molecular test for HCV RNA viral load measurement. A good correlation between the performances of Xpert with Abbott assay was seen in the present study. Both the assays are based on Real Time PCR based method for quantification of viral load. Though Abbott 2000 SP platform used in the study is a fully automated Real time PCR system with automation for RNA extraction but it

Conclusions

Molecular testing at the point-of-care, a step towards the de-centralization of services, is beginning to enter clinical practice in low income countries. Xpert HCV, a point-of-care molecular test, demonstrated good performance in viral load measurement and in treatment course monitoring consistency as compared to Abbott Real Time PCR test.

Competing interest

None declared.

Ethical approval

The ethical approval for the study was taken from the Institutes Ethical Committee.

Funding

None.

Acknowledgement

We acknowledge Mr Gaurav Singh for the technical support.

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