Systematic review of the accuracy of plasma preparation tubes for HIV viral load testing

Abstract

Expanding access to HIV viral load testing is essential to improving the care and treatment of people living with HIV/AIDS and ending the AIDS epidemic. Though significant investments have been made in the past five years, many high burden, low resource countries continue to have viral load access rates below 50%. Plasma preparation tubes (PPTs) can simplify storage, transport, and preparation of plasma used for viral load testing. A systematic review was conducted to evaluate the accuracy of plasma preparation tubes for HIV viral load testing. Study results regarding the accuracy of PPT viral load measurements across various storage and transportation conditions were examined. The quality of evidence was evaluated using GRADE and QUADAS-2 criteria. The review identified 16 studies using PPTs with data from 6,141 individuals from 1995 to 2014. Overall the quality of evidence was rated as moderate, with unclear applicability for studies evaluating viral load assays that are no longer commercially available. Significantly elevated viral load results (>0.3 log copies/ml difference) have been observed with PPTs; however, when manufacturer handling instructions are followed, when plasma is aliquoted into a secondary tube, or when PPTs are centrifuged prior to testing, PPT results only differed from standard EDTA plasma testing using commercially available viral load assays by a range on average of -0.03 to +0.08 log copies/ml across studies. Although spuriously elevated viral load results have been observed with PPTs, following proper sample handing techniques have been shown to provide accurate results. PPTs, therefore, provide a high quality alternative specimen type for countries seeking solutions to infrastructure and specimen transportation challenges in an effort to scale-up viral load testing and achieve 90-90-90 targets.

The Development of a Standardized Quality Assessment Material to Support Xpert® HIV-1 Viral Load Testing for ART Monitoring in South Africa

“…While studies showing long-term stability of HIV in whole blood are available [ 17 , 18 , 19 ], the manufacturers of the VL technologies recommend testing within 24 h, with separation of plasma within six hours and specimen refrigeration [ 20 , 21 ], primarily to maintain the quality of low VL specimens and to overcome the extreme temperatures (>30 °C) in many high HIV prevalence regions. The use of plasma preparation tubes (PPT; Becton Dickinson, Franklin Lakes, NJ, USA) was introduced [ 19 , 22 , 23 ] to increase the specimen transport window to at least 24 h [ 24 , 25 ], although specimens should still be separated within six hours of collection and prior to transport [ 19 ]. Alternative options to plasma-based testing include the use of dried blood spots (DBS) and several countries have shown that this is a feasible option for remote collection and centralized testing [ 26 , 27 , 28 , 29 , 30 , 31 ].…”

The Development of a Standardized Quality Assessment Material to Support Xpert HIV-1 Viral Load Testing for ART Monitoring in South Africa

“…While there are studies showing long-term stability of HIV in whole blood (20)(21)(22), the manufacturers of the VL technologies recommend testing within 24 hours, with separation of plasma within six hours and specimen refrigeration (23,24), primarily to maintain the quality of low VL specimens and to overcome the extreme temperatures (>30 o C) in many high HIV prevalence regions. The use of plasma preparation tubes (PPT; Becton Dickinson, USA) was introduced (22,25,26) to increase the specimen transport window to at least 24 hours (27,28), although specimens should still be separated within six hours of collection and prior to transport (22). Alternative options to plasma based testing include the use of dried blood spots (DBS) and several countries have shown that this is a feasible option for remote collection and central testing (29)(30)(31)(32)(33)(34)(35).…”