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Reliability of plasma HIV viral load testing beyond 24 hours: Insights gained from a study in a routine diagnostic laboratory.

ABSTRACT: BACKGROUND:Viral load testing is key to monitoring response to anti-retroviral therapy (ART). However, in lower and middle income countries with large epidemics, pre-analytical challenges threaten the quality of testing. It is unknown how much delayed processing and adverse storage affects the validity of results. The aim of this study was to determine the impact of delayed testing and warmer storage conditions on HIV RNA stability in diagnostic samples. METHODS:1194 samples, collected in EDTA or plasma preparation (PPT) tubes, were studied. Immediately after initial testing, primary tubes were stored for 72, 96 or 168 hours at 4°C, 20°C or 30°C. The viral load was then repeated and the 2 results were compared. RESULTS:Viral loads were very stable, with <0.5 log copies/ml median difference noted between paired tests for all storage times and temperatures. The viral load in samples stored for up to a week reliably differentiated between ART-suppressed and failing patients in 98.83% of instances. However, re-centrifugation immediately prior to repeat testing was essential to avoid falsely elevated readings, probably due to contamination of plasma with cell-associated viral nucleic acids. Approximately 20% of samples with initially undetectable viral loads were weakly positive (<100 copies/mL) on repeat. This was not exacerbated by duration or temperature of storage. CONCLUSION:Viral RNA in diagnostic samples is stable well beyond currently recommended limits. However, when testing stored primary samples, contamination of plasma with cellular material easily occurs. Low viral loads (<100copies/mL) in samples stored in this way should be interpreted with caution.

SUBMITTER: Hardie D

PROVIDER: S-EPMC6609026 | biostudies-literature | 2019

REPOSITORIES: biostudies-literature

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Reliability of plasma HIV viral load testing beyond 24 hours: Insights gained from a study in a routine diagnostic laboratory.

Hardie Diana D Korsman Stephen S Ameer Sharifa S Vojnov Lara L Hsiao Nei-Yuan NY

PloS one 20190703 7

<h4>Background</h4>Viral load testing is key to monitoring response to anti-retroviral therapy (ART). However, in lower and middle income countries with large epidemics, pre-analytical challenges threaten the quality of testing. It is unknown how much delayed processing and adverse storage affects the validity of results. The aim of this study was to determine the impact of delayed testing and warmer storage conditions on HIV RNA stability in diagnostic samples.<h4>Methods</h4>1194 samples, coll ...[more]

PMID: 31269089

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Project description:BackgroundSince the scale-up of routine viral load (VL) testing started in 2016, there is limited evidence on VL suppression rates under programmatic settings and groups at risk of non-suppression. We conducted a study to estimate VL non-suppression (> 1000 copies/ml) and its risk factors using "routine" and "repeat after enhanced adherence counselling (EAC)" VL results.MethodsWe conducted an analytic cross-sectional study using secondary VL testing data collected between 2014 and 2018 from a centrally located laboratory. We analysed data from routine tests and repeat tests after an individual received EAC. Our outcome was viral load non-suppression. Bivariable and multivariable logistic regression was performed to identify factors associated with having VL non-suppression for routine and repeat VL.ResultsWe analysed 103,609 VL test results (101,725 routine and 1884 repeat test results) collected from the country's ten provinces. Of the 101,725 routine and 1884 repeat VL tests, 13.8% and 52.9% were non-suppressed, respectively. Only one in seven (1:7) of the non-suppressed routine VL tests had a repeat test after EAC. For routine VL tests; males (vs females, adjusted odds ratio (aOR) = 1.19, [95% CI 1.14-1.24]) and adolescents (10-19 years) (vs adults (25-49 years), aOR = 3.11, [95% CI 2.9-3.31]) were more at risk of VL non-suppression. The patients who received care at the secondary level (vs primary, aOR = 1.21, [95% CI 1.17-1.26]) and tertiary level (vs primary, aOR = 1.63, [95% CI 1.44-1.85]) had a higher risk of VL non-suppression compared to the primary level. Those that started ART in 2014-2015 (vs < 2010, aOR = 0.83, [95% CI 0.79-0.88]) and from 2016 onwards (vs < 2010, aOR = 0.84, [95% CI 0.79-0.89]) had a lower risk of VL non-suppression. For repeat VL tests; young adults (20-24 years) (vs adults (25-49 years), (aOR) = 3.48, [95% CI 2.16 -5.83]), adolescents (10-19 years) (vs adults (25-49 years), aOR = 2.76, [95% CI 2.11-3.72]) and children (0-9 years) (vs adults (25-49 years), aOR = 1.51, [95% CI 1.03-2.22]) were at risk of VL non-suppression.ConclusionClose to 90% suppression in routine VL shows that Zimbabwe is on track to reach the third UNAIDS target. Strategies to improve the identification of clients with high routine VL results for repeating testing after EAC and ART adherence in subpopulations (men, adolescents and young adolescents) at risk of viral non-suppression should be prioritised.

Dataset Information

Reliability of plasma HIV viral load testing beyond 24 hours: Insights gained from a study in a routine diagnostic laboratory.

Publications

Reliability of plasma HIV viral load testing beyond 24 hours: Insights gained from a study in a routine diagnostic laboratory.

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