Nucleic acid amplification testing using dried blood spots to confirm the diagnosis of HIV-1 in adults.

Background: The WHO HIV testing algorithm for high prevalence populations recommends the use of three different serologic assays, though this approach may lead to diagnostic misclassification. The study objective was to compare dried blood spot (DBS)-based HIV-1 nucleic acid detection methods to determine their suitability to confirm the diagnosis of HIV-1 in adults generally with suppressed or low-level plasma HIV-1 RNA.

Methods: Four methods were evaluated: Cepheid Xpert HIV-1 Qual Assay (Xpert), Hologic Aptima HIV-1 Quant Dx assay (Aptima), Roche Cobas Ampliprep/Cobas TaqMan HIV-1 test, v.2.0 (CAP/CTM) with guanidinium-based sample pre-extraction buffer (SPEX), or CAP/CTM with phosphate-buffered saline (PBS). Testing was performed on 163 DBS samples collected from participants with HIV-1 in the AIDS Clinical Trial Group (ACTG) A5230 study (73 samples) and the Peninsula AIDS Research Cohort (PARC) study (90 samples).

Results: Xpert and SPEX CAP/CTM [96.9 % (158/163):95.7 % (156/163); P = 0.75) showed similar sensitivity. However, PBS CAP/CTM and Aptima demonstrated significantly lower sensitivity, 68.2 % (107/157) and 69.2 % (99/143), respectively, compared to Xpert and SPEX CAP/CTM (P < 0.0001 for all comparisons). Overall agreement between Xpert and SPEX CAP/CTM was 93.9 % (153/163), including 152 DBS samples in which both methods detected HIV-1 nucleic acids.

Conclusions: Xpert and SPEX CAP/CTM provide sensitive performance for the detection of HIV-1 nucleic acids using DBS collected from adults living with HIV-1, including those with suppressed virus loads. Given the cost and side-effects associated with inappropriate life-long antiretroviral therapy, these assays may play a role in diagnosing HIV-1 infection in individuals with suspected false-positive serologic testing.