Comparison of cobas HCV GT against Versant HCV Genotype 2.0 (LiPA) with confirmation by Sanger sequencing

BACKGROUND

Correct identification of infecting hepatitis C virus (HCV) genotype is helpful for targeted antiviral therapy.

OBJECTIVES

Here, we compared the HCV genotyping performance of the cobas HCV GT assay against the Versant HCV Genotype 2.0 (LiPA) assay, using 97 archived serum samples.

STUDY DESIGN

In the event of discrepant or indeterminate results produced by either assay, the core and NS5B regions were sequenced.

RESULTS

Of the 97 samples tested by the cobas, 25 (26%) were deemed indeterminate. Sequencing analyses confirmed 21 (84%) of the 25 samples as genotype 6 viruses with either subtype 6m, 6n, 6v, 6xa, or unknown subtype. Of the 97 samples tested by the LiPA, thirteen (13%) were deemed indeterminate. Seven (7%) were assigned with genotype 1, with unavailable/inconclusive results from the core region of the LiPA. Notably, the 7 samples were later found to be either genotype 3 or 6 by sequencing analyses. Moreover, 1 sample by the LiPA was assigned as genotypes 4 (cobas: indeterminate) but were later found to be genotype 3 by sequencing analyses, highlighting its limitation in assigning the correct genotype.

CONCLUSIONS

The cobas showed similar or slightly higher accuracy (100%; 95% CI 94-100%) compared to the LiPA (99%; 95% CI 92-100%). Twenty-six percent of the 97 samples tested by the cobas had indeterminate results, mainly due to its limitation in identifying genotype 6 other than subtypes 6a and 6b. This presents a significant assay limitation in Southeast Asia, where genotype 6 infection is highly prevalent.

Resolution of adefovir-related nephrotoxicity by adefovir dose-reduction in patients with chronic hepatitis B

BACKGROUND

Chronic hepatitis B patients (CHB) treated with adefovir were followed up to evaluate nephrotoxicity and its outcome.

AIM

To assess the incidence of renal dysfunction during adefovir therapy in Asian patients and factors associated with it, and evaluate strategies to improve adefovir-related renal dysfunction and their impact on viral suppression.

METHODS

Chronic hepatitis B clinic patients from a tertiary hospital on adefovir treatment, with their clinical and laboratory parameters were extracted from the hospital electronic clinical database in an observational study design. Patients were excluded if they had liver/renal transplant, baseline renal impairment or were on dialysis. Adefovir-related renal dysfunction was defined as adefovir-related abnormal serum creatinine (ARASC) > 125 μmol/L (males), >90 μmol/L (females); adefovir-related abnormal GFR <60 mL/min; and adefovir-related increased serum creatinine >0.5 mg/dL, without other known causes of nephrotoxicity.

RESULTS

A total of 271/383 adefovir-treated patients were suitable for analysis and 33(12%) patients developed abnormal serum creatinine. Cumulative increase in proportion of patients with ARASC was 33.8% and GFR ≤60 mL/min was 38.3% by 6 years, while serum creatinine increase ≥0.5 mg/dL was 21.48% by 5 years. Using multivariate analysis, the only independent baseline predictor of ARASC was GFR ≤76.1 mL/min. Patients who had ARASC had similar levels of viral suppression to those who did not have ARASC. Those who had ARASC either continued adefovir (24%), switched therapy (24%) or had adefovir dose reduction (52%). ARASC resolved and GFR normalised in almost all patients after either switching therapy or reducing adefovir dose, with no difference between the two strategies (P = 0.737). Those with adefovir dose reduction had no significant increase in HBV DNA (P = 0.170).

CONCLUSIONS

Adefovir-related renal dysfunction occurred in a significant number of adefovir-treated patients, but reduction of the dose led to renal improvement without compromising treatment efficacy.