Evaluation of the Alinity m HIV-1 assay for the quantification of HIV-1 RNA plasma viral load in a high-throughput molecular laboratory in South Africa

Abstract

Background: Regular HIV-1 viral load monitoring forms an essential part of any successful HIV-1 treatment programme. Abbott Molecular recently released the Alinity m HIV-1 assay to be run on the Alinity m System, a fully automated, continuous and random access analyser using ReadiFlex™ technology.

Objectives: Our study investigated the performance of the Alinity m HIV-1 assay in comparison to the cobas® HIV-1 test in a high-throughput molecular laboratory.

Study design: We compared the performance of the Alinity m HIV-1 assay with the cobas® HIV-1 test, performed on both the cobas® 4800 and cobas® 6800 systems at three clinically relevant thresholds (50, 200 and 1000 cp/mL).

Results: Excellent correlation (r = 0.98) and agreement (mean bias -0.004 Log₁₀ cp/mL) was achieved between the cobas® 4800 and Alinity m HIV-1 assay. While there was good correlation between the Alinity m HIV-1 assay and the cobas® 6800 (r = 0.99), Bland-Altman analysis indicated that the cobas® 6800 on average measured 0.22 Log₁₀ cp/mL higher than the Alinity m HIV-1 assay across the dynamic range. Percentage agreement was excellent at the 200 cp/mL and 1000 cp/mL thresholds and was slightly lower at 50 cp/mL in comparison with the cobas® systems.

Conclusions: The Alinity m HIV-1 assay compared well with the cobas® HIV-1 test on both the cobas® 4800 and cobas® 6800 systems in a high-throughput molecular laboratory in South Africa, a low- to middle-income country.

Keywords: Alinity m HIV-1; Cobas HIV-1; HIV-1 RNA; Viral load monitoring.