Comparison of the Abbott Alinity m and m2000 assays for the quantification of HIV-1, HCV and HBV in clinical samples.

BACKGROUND: Viral load (VL) determination is an essential parameter of the management of patients infected with HIV, HBV or HCV. Many available molecular systems run on a "batch" mode while "random access" systems provide more flexibility. OBJECTIVES: We compared the performance of HIV-1, HCV and HBV quantification assays on the recently developed Abbott Alinity m system to the m2000 RealTime assays. STUDY DESIGN: Plasma specimens sent for viral load determination were prospectively tested on m2000 and Alinity m systems, according to manufacturers' instructions. Additional low and high tittered samples were used to assess reproducibility. RESULTS: Assays concordance was evaluated from 180 samples for HIV-1, 122 for HBV, and 92 for HCV. A good correlation and a linear relation over the quantification range was observed for the three markers (r > 0.974). The Alinity m assays yielded higher results with a mean quantification bias of 0.22 log cp/ml for 75 HIV-1, 0.3 log IU/ml for 79 HBV, and 0.2 log for 35 HCV samples, though results were equivalent within an allowable difference of 0.3-0.4 log. Qualitative discordance was observed for 43/180 HIV results, 10/122 HBV and 7/92 HCV and involved undetectable or low-level VL. CONCLUSION: The Alinity m assays have performance equivalent to m2000. Upon implementation, physicians should be aware of the relative overquantification compared to previous Abbott assays, particularly around clinical decision thresholds. With reduced turnarounds and hands-on times compared to the m2000 system, the Alinity m platform may improve significantly the laboratory workflow efficiency for the benefit of physicians and patients.

Clinical performance of the VERIS HCV assay for hepatitis C virus RNA quantification.

BACKGROUND: Diagnosis of hepatitis C virus (HCV) infection and treatment monitoring rely on detection/quantification of HCV RNA and real-time polymerase chain reaction (PCR) techniques are expected to equivalently quantify the different HCV genotypes. OBJECTIVE: The clinical performance of the VERIS HCV assay for HCV RNA quantification was compared to that of the Abbott RealTime HCV assay. STUDY DESIGN: Qualitative concordance and quantitative comparison were evaluated on a first panel of 286 clinical samples containing HCV genotypes 1-6. Forty additional genotype 4 samples were tested to explore genotype 4 HCV RNA underquantification. RESULTS: Qualitative discrepancies were observed for low viral loads (<2 log10 IU/mL) in patients under antiviral therapy and would not have had any impact on patients' management with the current guidelines for the monitoring of patients on direct-acting antivirals (DAAs). Quantification results were well correlated (R2=0.89) with an overall minimal quantification bias (mean VERIS - Abbott difference) of -0.09 log10 IU/mL. Quantification agreement for genotypes 1, 2 and 3 samples was excellent, but reached -0.57 log10 IU/mL for 46 genotype 4 samples. A lower quantification bias of -0.24 log10 IU/mL was observed when testing 40 additional genotype 4 samples with a second reagent lot. Underquantification was not associated with 5' untranslated region (UTR) sequence polymorphisms but could be explained by 5' UTR RNA molecular modeling. CONCLUSION: HCV RNA quantification by the VERIS HCV assay and the Abbott RealTime HCV assay was well correlated for all HCV genotypes, except genotype 4 where 5' UTR RNA folding may impact quantification. Nevertheless, this underestimation of HCV RNA levels had no impact on clinical use.