Performance of patient-collected dried blood spot specimens for HIV-1 viral load testing: evidence from the DO ART Study in South Africa.

OBJECTIVE Evaluate the clinical utility of patient-collected dried blood spots (DBS) in measuring HIV-1 viral load (VL) for monitoring antiretroviral therapy (ART) compared to provider-collected DBS and blood plasma. DESIGN In a randomized trial of community-based delivery of ART in South Africa, we assessed performance of: (1) DBS specimens compared to plasma, and (2) participant-collected versus staff-collected DBS specimens, to measure HIV-1 VL. METHODS The bioMérieux NucliSENS EasyQ HIV-1 v2.0 assay was used for VL measurement. From October 2017 to November 2019, we collected 996 pairs of plasma/DBS specimens from 760 participants and 315 pairs of staff-/participant-collected DBS cards from 261 participants. We assessed DBS test sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) using the WHO failure threshold of 1000 copies/mL. Log-transformed VL was compared using concordance correlation coefficients (CCC) and mean differences from linear mixed models. RESULTS In a population with 13% detectable VL, DBS VL compared with plasma VL had 91% (95% CI: 86-95) sensitivity, 99% (98-100) specificity, 94% (90-98) PPV, and 99% (98-99) NPV. We observed high agreement between staff-collected DBS VL and plasma VL (CCC: 0.94), and between participant-collected DBS VL and plasma VL (CCC: 0.92). Correlation between participant- and staff-collected DBS was very high (CCC: 0.97; mean difference for those with a detectable result: -0.10 log10 copies/mL [-0.21-0.02]). CONCLUSIONS VL results from participant-collected DBS are clinically comparable with those collected by clinical staff and using blood plasma. Self-collected DBS has potential for use for ART monitoring outside the clinic.