CROI 2015 Program and Abstracts

Abstract Listing

Poster Abstracts

Conclusions: The Alere q HIV-1/2 Detect test is a novel, rapid and simple device that detects HIV-2 RNA in clinical samples and differentiates between HIV-1 and HIV-2 with a high level of specificity. It is designed to use small samples (finger prick; 25 m L) of whole blood and plasma and has the potential for use as a rapid HIV-2 NAT-based diagnostic and a viral load monitoring device in resource-limited settings, as well as providing confirmation of HIV-2 infection in the new CDC algorithm for HIV testing. 615 Performance of HIV Viral Load with Dried Blood Spots in Children on ART in Mozambique Amina M. de Sousa Muhate 1 ; James C. Houston 2 ; Mariamo Assane 1 ; Joy Chang 2 ; Emilia Koumans 2 ; IleshV. Jani 1 ; Jennifer Sabatier 2 ; Paula M.Vaz 3 ; ChunfuYang 2 ; Emilia Rivadeneira 2 1 Ministry of Health, Mozambique, Mozambique; 2 Centers for Disease Control and Prevention, Atlanta, GA, US; 3 Fundação Ariel Glaser Contra o SIDA Pediátrico, Maputo, Mozambique Background: The World Health Organization (WHO) recommends using HIV viral load (VL) to monitor antiretroviral treatment (ART) and detect virologic failure (VF) (>1000 copies/mL). However, the gold standard sample, plasma, is challenging to process for patients living in remote areas due to requirements for plasma separation, transportation, and storage. Dried blood spots collected by finger stick (FS-DBS) can overcome the stringent requirements of plasma for VL testing and allowmore patients to access the HIV VL test. However there is limited evidence on the validity of FS-DBS to estimate VF at 1000 copies/ml and no evaluations have focused on children. In this study, we compared the performance of HIV VL testing using DBS as an alternative to the plasma for VL testing for children on ART. Methods: Paired plasma and FS-DBS were collected from 717 children on ART 12 months at six sites in Maputo, Mozambique. Plasma was prepared from venous blood. DBS were prepared for each child by lay health care workers who used finger-sticks to collect blood in micro-EDTA tubes and spotted DBS (FS-DBS) with transfer pipette with 75 μ L of blood per spot. Plasma VL was performed using COBAS Amplipre/COBAS TaqMan HIV-1 Test, V 2.0 and DBS VL was tested using Abbott m2000 HIV-1 DBS Quant, V4 with one spot per test at CDC-Atlanta. All statistical analysis accounted for clustering within sites. Results: The performance characteristics of DBS VL at thresholds of 1000, 3000, and 5000 copies/mL were compared with plasma VL at 1000 copies/mL as the gold standard. The sensitivity and specificity for each DBS VL threshold were estimated (Table 1). Table 1. Sensitivity, Specificity, and Kappa agreement by DBS VF threshold compared to gold standard plasma Roche among children (n=717) Conclusions: Our DBS VL data demonstrated very good specificities (97.6%, 98.8%, 99.3%) or low false positivity rates for VF at all three thresholds meaning that very few patients will be misclassified for treatment failure when using this methodology for collecting and analyzing DBS for VL testing. However the sensitivity was lower at all thresholds (79.8, 70.6, 63.4) thus clinicians must be aware of the possibility of false negative results and need to take into account clinical findings when interpreting FS-DBS VL. The false negativity rate was lowest using the threshold of 1000 copies/ml 20.2% vs 29.4 (3000 copies/ml) or 36.6 (5000 copies/ml). Therefore, 1000 copies/mL can be used as the threshold to monitor ART and detect treatment failure when using DBS for VL testing. 616 Cost-Effectiveness of Pooled PCR Testing of Dried Blood Spots for Infant HIV Diagnosis Cari van Schalkwyk 2 ; Jean Maritz 2 ; Alex Welte 1 ; Gert U. van Zyl 2 ;Wolfgang Preiser 2 1 University of Stellenbosch, South Africa, Stellenbosch, South Africa; 2 University of Stellenbosch, Tygerberg, South Africa Background: Early diagnosis and initiation on antiretroviral therapy is important for the improved prognosis of HIV infected infants. In resource limited settings, restricted access to qualitative polymerase chain reaction (PCR) amplifies the need for diagnostic tools with improved cost-effectiveness. This study investigates the potential savings achievable by pooling dried blood spots (DBS) for PCR testing, defined as combining multiple patient samples in a single assay run with subsequent individual testing of positive pools. Pooling has previously been shown to enhance efficiency of virological monitoring of therapy. Methods: Testing demand and technician and reagent costs at a centralised laboratory in the Western Cape, South Africa were monitored. Preparation time and sensitivity/ specificity of both the pooling strategy and individual testing was determined on a sample of 295 specimens in 39 HIV reactive and 20 HIV non-reactive pools, using an automated commercial PCR platform. A dynamic model, using all this data as inputs, was built to simulate cost savings for a one year period. Results: The laboratory feasibility study confirmed the utility of the pooling approach, achieving a sensitivity of 100% (35/35; or, when low-positive/inconclusive samples were included 38/39 i.e. 97.4%), as well as a specificity of 100% (20/20). From July 2012 to June 2013, this lab received an average of 38 samples per day with an overall HIV prevalence of 2%. Savings would have been 66% of direct laboratory costs if a pooling strategy of 5 DBS per pool was followed. Larger pool sizes are theoretically more cost effective but infeasible within the present automated extraction procedure. Technician time spent would only be marginally less, but the median number of runs per day would have reduced by 50%. Figure 1 illustrates percentage cost saved per year, as a function of prevalence, at different pool sizes, for a laboratory that tests 150 samples per day.

Poster Abstracts

Figure 1: Percentage cost saved per year, as a function of prevalence, at different pool sizes, for a laboratory that tests 150 samples per day.

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CROI 2015