Comparative evaluation of Aptima HIV-1 Qualitative RNA assay performance using plasma and serum specimens from persons with established HIV-1 infection

Abstract

Background: Blood specimens for HIV testing are frequently collected using serum collection tubes. The Aptima HIV-1 RNA Qualitative test, originally approved for diagnostic use as a supplemental test for use with plasma, is now approved for use with serum, and may be used in new laboratory-based HIV testing algorithms which detect acute and established HIV infections.

Objectives: To compare the sensitivity of Aptima using serum and plasma specimens from persons with established HIV infection.

Study design: Parallel serum and plasma specimens were collected from 325 persons with established HIV-1 infection who had positive immunoassay (IA) and Western blot (WB) results. Samples with negative Aptima results were considered false-negative and were subjected to repeat testing. Aptima sensitivity for serum and plasma was calculated relative to IA and WB, and compared using the McNemar test.

Results: The sensitivity of Aptima using serum (97.23%, 95% confidence interval [CI] 94.81-98.73) was similar to that using plasma (97.54%, 95% [CI] 95.21-98.93) p=1.00. Five of ten specimens initially false-negative on either serum or plasma were reactive on repeat testing. No specimens initially classified as false-negative on both matrices were reactive on both matrices on repeat testing.

Conclusions: In specimens from persons with established infections, Aptima performed with similar sensitivity when used with serum or plasma. Using serum for immunoassay screening and supplemental testing may provide added convenience for laboratories.