Catalogue Search | MBRL
Search Results Heading
Explore the vast range of titles available.
MBRLSearchResults
-
DisciplineDiscipline
-
Is Peer ReviewedIs Peer Reviewed
-
Item TypeItem Type
-
SubjectSubject
-
YearFrom:-To:
-
More FiltersMore FiltersSourceLanguage
Done
Filters
Reset
511
result(s) for
"Stevens, Wendy"
Sort by:
Estimating retention in HIV care accounting for patient transfers: A national laboratory cohort study in South Africa
by
MacLeod, William B.
,
Carmona, Sergio
,
Maskew, Mhairi
in
Acquired immune deficiency syndrome
,
Adult
,
AIDS
2018
Systematic reviews have described high rates of attrition in patients with HIV receiving antiretroviral therapy (ART). However, migration and clinical transfer may lead to an overestimation of attrition (death and loss to follow-up). Using a newly linked national laboratory database in South Africa, we assessed national retention in South Africa's national HIV program.
Patients receiving care in South Africa's national HIV program are monitored through regular CD4 count and viral load testing. South Africa's National Health Laboratory Service has maintained a database of all public-sector CD4 count and viral load results since 2004. We linked individual laboratory results to patients using probabilistic matching techniques, creating a national HIV cohort. Validation of our approach in comparison to a manually matched dataset showed 9.0% undermatching and 9.5% overmatching. We analyzed data on patients initiating ART in the public sector from April 1, 2004, to December 31, 2006, when ART initiation could be determined based on first viral load among those whose treatment followed guidelines. Attrition occurred on the date of a patient's last observed laboratory measure, allowing patients to exit and reenter care prior to that date. All patients had 6 potential years of follow-up, with an additional 2 years to have a final laboratory measurement to be retained at 6 years. Data were censored at December 31, 2012. We assessed (a) national retention including all laboratory tests regardless of testing facility and (b) initiating facility retention, where laboratory tests at other facilities were ignored. We followed 55,836 patients initiating ART between 2004 and 2006. At ART initiation, median age was 36 years (IQR: 30-43), median CD4 count was 150 cells/mm3 (IQR: 81-230), and 66.7% were female. Six-year initiating clinic retention was 29.1% (95% CI: 28.7%-29.5%). After allowing for transfers, national 6-year retention was 63.3% (95% CI: 62.9%-63.7%). Results differed little when tightening or relaxing matching procedures. We found strong differences in retention by province, ranging from 74.2% (95% CI: 73.2%-75.2%) in Western Cape to 52.2% (95% CI: 50.6%-53.7%) in Mpumalanga at 6 years. National attrition was higher among patients initiating at lower CD4 counts and higher viral loads, and among patients initiating ART at larger facilities. The study's main limitation is lack of perfect cohort matching, which may lead to over- or underestimation of retention. We also did not have data from KwaZulu-Natal province prior to 2010.
In this study, HIV care retention was substantially higher when viewed from a national perspective than from a facility perspective. Our results suggest that traditional clinical cohorts underestimate retention.
Journal Article
Rituximab in patients with primary CNS lymphoma (HOVON 105/ALLG NHL 24): a randomised, open-label, phase 3 intergroup study
by
Doorduijn, Jeanette K
,
Stevens, Wendy B C
,
Beeker, Aart
in
B-cell lymphoma
,
Cancer
,
CD20 antigen
2019
The prognosis for primary CNS lymphoma has improved with the use of high-dose methotrexate-based chemotherapy, but patient outcomes remain poor. Rituximab, a chimeric monoclonal antibody that targets the CD20 cell surface protein, has substantial activity in systemic CD20-positive diffuse large B-cell lymphoma, but its efficacy in primary CNS lymphoma is unknown and low penetration of the large rituximab molecule through the blood–brain barrier could limit its effect. We aimed to investigate the addition of rituximab to a high-dose methotrexate-based chemotherapy regimen in patients with newly diagnosed primary CNS lymphoma.
This intergroup, multicentre, open-label, randomised phase 3 study was done at 23 hospitals in the Netherlands, Australia, and New Zealand. Non-immunocompromised patients aged 18–70 years with newly diagnosed primary CNS lymphoma were randomly assigned (1:1) to receive methotrexate-based chemotherapy with or without intravenous rituximab. We used a web-based randomisation system with stratification by centre, age, and Eastern Cooperative Oncology Group–WHO performance status, and a minimisation procedure. All group assignment was open label and neither investigators nor patients were masked to allocation. All patients were treated with two 28-day cycles of induction chemotherapy, consisting of intravenous methotrexate 3 g per m2 on days 1 and 15, intravenous carmustine 100 mg per m2 on day 4, intravenous teniposide 100 mg per m2 on days 2 and 3, and oral prednisone 60 mg per m2 on days 1–5, with (R-MBVP) or without (MBVP) intravenous rituximab 375 mg per m2 on days 0, 7, 14, and 21 in cycle one and days 0 and 14 in cycle two. Patients with response at the end of induction subsequently received high-dose cytarabine and, in patients aged 60 years or younger, low-dose whole-brain radiotherapy. The primary endpoint was event-free survival, with events defined as not reaching complete response or complete response unconfirmed at the end of treatment, or progression or death after response; analysis was adjusted for age and performance score. Patients were analysed on a modified intention-to-treat basis. This trial is registered with the Nederlands Trial Register, number NTR2427, and the Australian New Zealand Clinical Trials Registry, number ACTRN12610000908033. The trial was closed on May 27, 2016, after achieving complete accrual, and follow-up is ongoing.
Between Aug 3, 2010, and May 27, 2016, we recruited 200 patients (109 men and 91 women; median age was 61 years [IQR 55–67]). We randomly assigned 100 patients to MBVP and 99 patients to R-MBVP. One patient was randomly assigned to the R-MBVP group but found to be ineligible because of an incorrect diagnosis and was excluded from all analyses. After a median follow-up of 32·9 months (IQR 23·9–51·5), 98 patients had had an event (51 in the MBVP group and 47 in the R-MBVP group), of whom 79 had died (41 in the MBVP group and 38 in the R-MBVP group). Event-free survival at 1 year was 49% (95% CI 39–58) in the MBVP group (no rituximab) and 52% (42–61) in the R-MBVP group (with rituximab; hazard ratio 1·00, 95% CI 0·70–1·43, p=0·99). Grade 3 or 4 adverse events occurred in 58 (58%) patients in the MBVP group and 63 (64%) patients in the R-MBVP group, with infections (24 [24%] patients receiving MBVP vs 21 [21%] patients receiving R-MBVP), haematological toxicity (15 [15%] vs 12 [12%]), and nervous system disorders (ten [10%] vs 15 [15%]) being the most common. Life-threatening or fatal serious adverse events occurred in 12 (12%) patients in the MBVP group and ten (10%) patients in the R-MBVP group, and five (5%) patients in the MBVP group and three (3%) in the R-MBVP group died from treatment-related causes.
We found no clear benefit of addition of rituximab to methotrexate, carmustine, teniposide, and prednisone chemotherapy in primary CNS lymphoma. Therefore, the results of this study do not support the use of rituximab as a component of standard treatment in primary CNS lymphoma.
Roche, the Dutch Cancer Society, and Stichting STOPhersentumoren.
Journal Article
Early assessment of the clinical severity of the SARS-CoV-2 omicron variant in South Africa: a data linkage study
2022
The SARS-CoV-2 omicron variant of concern was identified in South Africa in November, 2021, and was associated with an increase in COVID-19 cases. We aimed to assess the clinical severity of infections with the omicron variant using S gene target failure (SGTF) on the Thermo Fisher Scientific TaqPath COVID-19 PCR test as a proxy.
We did data linkages for national, South African COVID-19 case data, SARS-CoV-2 laboratory test data, SARS-CoV-2 genome data, and COVID-19 hospital admissions data. For individuals diagnosed with COVID-19 via TaqPath PCR tests, infections were designated as either SGTF or non-SGTF. The delta variant was identified by genome sequencing. Using multivariable logistic regression models, we assessed disease severity and hospitalisations by comparing individuals with SGTF versus non-SGTF infections diagnosed between Oct 1 and Nov 30, 2021, and we further assessed disease severity by comparing SGTF-infected individuals diagnosed between Oct 1 and Nov 30, 2021, with delta variant-infected individuals diagnosed between April 1 and Nov 9, 2021.
From Oct 1 (week 39), 2021, to Dec 6 (week 49), 2021, 161 328 cases of COVID-19 were reported in South Africa. 38 282 people were diagnosed via TaqPath PCR tests and 29 721 SGTF infections and 1412 non-SGTF infections were identified. The proportion of SGTF infections increased from two (3·2%) of 63 in week 39 to 21 978 (97·9%) of 22 455 in week 48. After controlling for factors associated with hospitalisation, individuals with SGTF infections had significantly lower odds of admission than did those with non-SGTF infections (256 [2·4%] of 10 547 vs 121 [12·8%] of 948; adjusted odds ratio [aOR] 0·2, 95% CI 0·1–0·3). After controlling for factors associated with disease severity, the odds of severe disease were similar between hospitalised individuals with SGTF versus non-SGTF infections (42 [21%] of 204 vs 45 [40%] of 113; aOR 0·7, 95% CI 0·3–1·4). Compared with individuals with earlier delta variant infections, SGTF-infected individuals had a significantly lower odds of severe disease (496 [62·5%] of 793 vs 57 [23·4%] of 244; aOR 0·3, 95% CI 0·2–0·5), after controlling for factors associated with disease severity.
Our early analyses suggest a significantly reduced odds of hospitalisation among individuals with SGTF versus non-SGTF infections diagnosed during the same time period. SGTF-infected individuals had a significantly reduced odds of severe disease compared with individuals infected earlier with the delta variant. Some of this reduced severity is probably a result of previous immunity.
The South African Medical Research Council, the South African National Department of Health, US Centers for Disease Control and Prevention, the African Society of Laboratory Medicine, Africa Centers for Disease Control and Prevention, the Bill & Melinda Gates Foundation, the Wellcome Trust, and the Fleming Fund.
Journal Article
Heterosexual HIV-1 transmission after initiation of antiretroviral therapy: a prospective cohort analysis
by
Celum, Connie
,
Cohen, Craig R
,
Kiarie, James
in
Acquired immune deficiency syndrome
,
Adult
,
AIDS
2010
High plasma HIV-1 RNA concentrations are associated with increased risk of HIV-1 transmission. Initiation of antiretroviral therapy (ART) reduces plasma HIV-1 concentrations. We aimed to assess the effect of ART use by patients infected with HIV-1 on risk of transmission to their uninfected partners.
Participants in our prospective cohort analysis were from a randomised placebo-controlled trial that enrolled heterosexual African adults who were seropositive for both HIV-1 and herpes simplex virus type 2, and their HIV-1 seronegative partners. At enrolment, HIV-1 infected participants had CD4 counts of 250 cells per μL or greater and did not meet national guidelines for ART initiation; during 24 months of follow-up, CD4 counts were measured every 6 months and ART was initiated in accordance with national guidelines. Uninfected partners were tested for HIV-1 every 3 months. The primary outcome was genetically-linked HIV-1 transmission within the study partnership. We assessed rates of HIV-1 transmission by ART status of infected participants.
3381 couples were eligible for analysis. 349 (10%) participants with HIV-1 initiated ART during the study, at a median CD4 cell count of 198 (IQR 161–265) cells per μL. Only one of 103 genetically-linked HIV-1 transmissions was from an infected participant who had started ART, corresponding to transmission rates of 0·37 (95% CI 0·09–2·04) per 100 person-years in those who had initiated treatment and 2·24 (1·84–2·72) per 100 person-years in those who had not—a 92% reduction (adjusted incidence rate ratio 0·08, 95% CI 0·00–0·57, p=0·004). In participants not on ART, the highest HIV-1 transmission rate (8·79 per 100 person-years) was from those with CD4 cell counts lower than 200 cells per μL. In couples in whom the untreated HIV-1 infected partner had a CD4 cell count greater than 200 cells per μL, 66 (70%) of 94 transmissions occurred when plasma HIV-1 concentrations exceeded 50 000 copies per mL.
Low CD4 cell counts and high plasma HIV-1 concentrations might guide use of ART to achieve an HIV-1 prevention benefit. Provision of ART to HIV-1 infected patients could be an effective strategy to achieve population-level reductions in HIV-1 transmission.
Bill & Melinda Gates Foundation; US National Institutes of Health.
Journal Article
Xpert MTB/RIF Ultra for detection of Mycobacterium tuberculosis and rifampicin resistance: a prospective multicentre diagnostic accuracy study
2018
The Xpert MTB/RIF assay is an automated molecular test that has improved the detection of tuberculosis and rifampicin resistance, but its sensitivity is inadequate in patients with paucibacillary disease or HIV. Xpert MTB/RIF Ultra (Xpert Ultra) was developed to overcome this limitation. We compared the diagnostic performance of Xpert Ultra with that of Xpert for detection of tuberculosis and rifampicin resistance.
In this prospective, multicentre, diagnostic accuracy study, we recruited adults with pulmonary tuberculosis symptoms presenting at primary health-care centres and hospitals in eight countries (South Africa, Uganda, Kenya, India, China, Georgia, Belarus, and Brazil). Participants were allocated to the case detection group if no drugs had been taken for tuberculosis in the past 6 months or to the multidrug-resistance risk group if drugs for tuberculosis had been taken in the past 6 months, but drug resistance was suspected. Demographic information, medical history, chest imaging results, and HIV test results were recorded at enrolment, and each participant gave at least three sputum specimen on 2 separate days. Xpert and Xpert Ultra diagnostic performance in the same sputum specimen was compared with culture tests and drug susceptibility testing as reference standards. The primary objectives were to estimate and compare the sensitivity of Xpert Ultra test with that of Xpert for detection of smear-negative tuberculosis and rifampicin resistance and to estimate and compare Xpert Ultra and Xpert specificities for detection of rifampicin resistance. Study participants in the case detection group were included in all analyses, whereas participants in the multidrug-resistance risk group were only included in analyses of rifampicin-resistance detection.
Between Feb 18, and Dec 24, 2016, we enrolled 2368 participants for sputum sampling. 248 participants were excluded from the analysis, and 1753 participants were distributed to the case detection group (n=1439) and the multidrug-resistance risk group (n=314). Sensitivities of Xpert Ultra and Xpert were 63% and 46%, respectively, for the 137 participants with smear-negative and culture-positive sputum (difference of 17%, 95% CI 10 to 24); 90% and 77%, respectively, for the 115 HIV-positive participants with culture-positive sputum (13%, 6·4 to 21); and 88% and 83%, respectively, across all 462 participants with culture-positive sputum (5·4%, 3·3 to 8·0). Specificities of Xpert Ultra and Xpert for case detection were 96% and 98% (−2·7%, −3·9 to −1·7) overall, and 93% and 98% for patients with a history of tuberculosis. Xpert Ultra and Xpert performed similarly in detecting rifampicin resistance.
For tuberculosis case detection, sensitivity of Xpert Ultra was superior to that of Xpert in patients with paucibacillary disease and in patients with HIV. However, this increase in sensitivity came at the expense of a decrease in specificity.
Government of Netherlands, Government of Australia, Bill & Melinda Gates Foundation, Government of the UK, and the National Institute of Allergy and Infectious Diseases.
Journal Article
Moderate Levels of Pre-Treatment HIV-1 Antiretroviral Drug Resistance Detected in the First South African National Survey
by
Carmona, Sergio
,
Papathanasopoulos, Maria A.
,
Stevens, Wendy S.
in
Adult
,
Anti-HIV Agents - therapeutic use
,
Anti-Retroviral Agents - therapeutic use
2016
In order to assess the level of transmitted and/or pre-treatment antiretroviral drug resistance to HIV-1, the World Health Organization (WHO) recommends that regular surveys are conducted. This study's objective was to assess the frequency of HIV-1 antiretroviral drug resistance in patients initiating antiretroviral treatment (ART) in the public sector throughout South Africa.
A prospective cross-sectional survey was conducted using probability proportional to size sampling. This method ensured that samples from each province were proportionally collected, based on the number of patients receiving ART in each region. Samples were collected between March 2013 and October 2014. Pol sequences were obtained using RT-PCR and Sanger sequencing and submitted to the Stanford Calibrated Population Resistance tool v6.0.
A total of 277 sequences were available for analysis. Most participants were female (58.8%) and the median age was 34 years (IQR: 29-42). The median baseline CD4-count was 149 cells/mm3 (IQR: 62-249) and, based on self-reporting, participants had been diagnosed as HIV-positive approximately 44 days prior to sample collection (IQR: 23-179). Subtyping revealed that 98.2% were infected with HIV-1 subtype C. Overall, 25 out of 277 patients presented with ≥1 surveillance drug resistance mutation (SDRM, 9.0%, 95% CI: 6.1-13.0%). Non-nucleoside reverse transcriptase inhibitor (NNRTI) mutations were the most numerous mutations detected (n = 23). Only two patients presented with a protease inhibitor (PI) mutation. In four patients ≥4 SDRMs were detected, which might indicate that these patients were not truly ART-naïve or were infected with a multi-resistant virus.
These results show that the level of antiretroviral drug resistance in ART-naïve South Africans has reached moderate levels, as per the WHO classification. Therefore, regular surveys of pre-treatment drug resistance levels in all regions of South Africa is highly recommended to monitor the changing levels of pre-treatment antiretroviral drug resistance.
Journal Article
Using laboratory data to assess the impact of coronavirus (COVID-19) on reflex cryptococcal antigenaemia (CrAg) testing in South Africa
by
Glencross, Deborah Kim
,
Coetzee, Lindi Marie
,
Stevens, Wendy Susan
in
Adolescent
,
Adult
,
Antifungal agents
2023
Coronavirus disease (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), was first reported in Wuhan, China. Due to the rapid spread globally, it was declared a pandemic in March 2020. Social distancing and lockdown measures were introduced to limit transmission. These strategies could potentially impact the diagnosis and treatment of patients with advanced HIV who are susceptible to secondary infections like cryptococcal disease. In South Africa, reflexed cryptococcal antigenaemia (CrAg) testing and pre-emptive antifungal treatment are recommended preceding antiretroviral therapy initiation for patients with a CD4<100 cells/μl. This study aimed to assess the impact of COVID-19 on CrAg testing in South Africa.
Specimen-level data was extracted for individuals ≥15 years from the National Health Laboratory Services repository for calendar years 2018 to 2021. Test volumes and CrAg positivity were assessed at national and provincial levels, by age category and gender. The percentage change in annual and monthly CrAg test volumes for 2020 and 2021 (during lockdown levels) are compared to data reported for 2018. The monthly median CD4 and the percentage of samples with a count <25, 25-50, 51-75 and >75-<100 cells/μl were assessed.
Specimen data of 11 944 929 CD4 results included 1 306 456 CrAg tests. Annual CD4 and CrAg test volumes declined by 22.4% and 27.8% for 2020 and 2021 respectively (relative to 2018). There were 23 670 CrAg positive outcomes in 2018 compared to 21 399 (-9.6%) and 17 847 (-24.6%) in 2020 and 2021 respectively. A monthly test volume reduction of up to 36.6%, 35.5%, 36.1% and 13.3% was reported for infection waves one to four. CrAg detection increased from 6.3% in 2018 to 7.5% in 2020. More testing was offered to males (>56%) with a higher detection rate of 8.1% in 2020. Between 81.0% and 81.8% of testing was for patients aged 20 to 49 years. The monthly percentage of specimens <25 cells/μl ranged from 30.2% (June 2019) to 35.3% (August 2020). Overall, the monthly median CD4 ranged from 39 (IQR: 15-70)(August 2020) to 45 (IQR: 19-72)(March 2019) cells/μl. In 2020, the provincial percentage change in CrAg test volumes ranged from 2.9% to -33.7%.
Our findings confirmed the impact of lockdown measures on both the absolute number of CrAg tests performed and detection (increase in 2020). A smaller impact on the median CD4 was noted. The long-term impact on patient management in immune- compromised individuals needs further investigation.
Journal Article
Challenges, innovations and considerations for the use of tongue swabs in Mycobacterium tuberculosis complex detection
by
Scott, Lesley
,
David, Anura
,
Peloakgosi-Shikwambani, Keneilwe
in
Adult
,
Biology and Life Sciences
,
Buffers
2025
Sputum-based testing is most used for diagnosing pulmonary tuberculosis (TB), but non-sputum specimens such as tongue swabs (TS) offer additional approaches for detecting Mycobacterium tuberculosis complex (MTBC). This two-phase study evaluated various storage, transport, and processing conditions to improve MTBC detection using TS tested on quantitative PCR (qPCR) and Xpert MTB/RIF Ultra (Ultra).
Adults (≥18 years) with Ultra-positive sputum were enrolled at a healthcare facility in Johannesburg, South Africa. In Phase 1, five serial TS were collected per participant and transported \"dry\" at 2-8°C, to the testing laboratory. In Phase 2, seven TS were collected: three stored \"dry,\" two in Tris-EDTA (TE) buffer, and two in PrimeStore® Molecular Transport Medium (MTM). Across both phases, pre-testing methods included heat lysis (HL)-only or HL combined with vortex bead beating (VBB), and storage at varying temperatures before qPCR. Swabs stored in MTM were tested on Ultra.
A paired t-test revealed no statistically significant differences in Ct values between sequentially collected TS (adjusted p > 0.05). Similarly, mean IS6110/IS1081 Ct values did not differ between fresh and frozen samples (t (85) = -0.031, p = 0.98; 95% CI: -0.44 to 0.43). VBB significantly reduced Ct values compared to HL alone (t (85) = -9.67, p = 2.422 x 10-15; 95% CI: -2.44 to -1.61). While storage conditions influenced Ct value and consistency to some extent, mean Ct values varied slightly from 32.48-34.28. Ultra detection improved when TS were processed with MTM and SR buffer.
MTBC detection from serially collected TS was variable, but Ct values were consistent across swab order and storage conditions. VBB improved yield on qPCR, and Ultra detection was enhanced with diluted SR buffer, highlighting the value of optimized processing. These findings support the continued development of TS-based TB diagnostics.
Journal Article
High Prevalence of the K65R Mutation in HIV-1 Subtype C Infected Patients Failing Tenofovir-Based First-Line Regimens in South Africa
by
Lukhwareni, Azwidowi
,
Papathanasopoulos, Maria A.
,
Stevens, Wendy S.
in
Acquired immune deficiency syndrome
,
Adenine - analogs & derivatives
,
Adenine - pharmacology
2015
Tenofovir (TDF) has replaced stavudine (d4T) as the preferred nucleoside reverse transcriptase inhibitor (NRTI) in first-line regimens in South Africa, but limited information is available on the resistance patterns that develop after the introduction of TDF. This study investigated the antiretroviral drug resistance patterns in South African HIV-1 subtype C-infected patients failing stavudine- (d4T) and tenofovir- (TDF) based first-line regimens and assess the suitability of TDF as the preferred first-line nucleotide reverse transcriptase inhibitor (NRTI).
Resistance patterns of HIV-1 from 160 adult patients virologically failing TDF- (n = 80) and d4T- (n = 80) based first-line regimens were retrospectively analyzed. The pol gene was sequenced using an in-house protocol and mutations were analysed using the IAS-USA 2014 Drug Resistance Mutation list.
Compared to d4T-exposed patients (n = 7), patients failing on a TDF-containing regimen (n = 43) were almost 5 times more likely to present with a K65R mutation (aRR 4.86 95% CI 2.29 - 10.34). Y115F was absent in the d4T group, and detected in 13.8% (n = 11) of TDF-exposed patients, p = 0.0007. Virus from 9 of the 11 patients (82.0%) who developed the Y115F mutation also developed K65R. Intermediate or high-level resistance to most NRTIs was common in the TDF-treatment group, but these patients twice more likely to remain susceptible to AZT as compared to those exposed to d4T (aRR 2.09 95% CI 1.13 - 3.90).
The frequency of the TDF induced K65R mutation was higher in our setting compared to non-subtype C dominated countries. However, despite the higher frequency of cross-resistance to NRTIs, most patients remained susceptible to AZT, which is reflected in the South African treatment guidelines that recommend AZT as an essential component of second-line regimens.
Journal Article
Options to Expand HIV Viral Load Testing in South Africa: Evaluation of the GeneXpert® HIV-1 Viral Load Assay
2016
Expansion of HIV viral load (VL) testing services are required to meet increased targets for monitoring patients on antiretroviral treatment. South Africa currently tests >4million VLs per annum in 16 highly centralised, automated high-throughput laboratories. The Xpert HIV-1 VL assay (Cepheid) was evaluated against in-country predicates, the Roche Cobas Taqmanv2 and Abbott HIV-1RT, to investigate options for expanding VL testing using GeneXpert's random access, polyvalent capabilities and already established footprint in South Africa with the Xpert MTB/RIF assay (207 sites). Additionally, the performance of Xpert HIV-1VL on alternative, off-label specimen types, Dried Blood Spots (DBS) and whole blood, was investigated.
Precision, accuracy (agreement) and clinical misclassification (1000cp/ml) of Xpert HIV-1VL plasma was compared to Taqmanv2 (n = 155) and Abbott HIV-1 RT (n = 145). Misclassification of Xpert HIV-1VL was further tested on DBS (n = 145) and whole blood (n = 147).
Xpert HIV-1VL demonstrated 100% concordance with predicate platforms on a standardised frozen, plasma panel (n = 42) and low overall percentage similarity CV of 1.5% and 0.9% compared to Taqmanv2 and Abbott HIV-1 RT, respectively. On paired plasma clinical specimens, Xpert HIV-1VL had low bias (SD 0.32-0.37logcp/ml) and 3% misclassification at the 1000cp/ml threshold compared to Taqmanv2 (fresh) and Abbott HIV-1 RT (frozen), respectively. Xpert HIV-1VL on whole blood and DBS increased misclassification (upward) by up to 14% with increased invalid rate. All specimen testing was easy to perform and compatible with concurrent Xpert MTB/RIF Tuberculosis testing on the same instrument.
The Xpert HIV-1VL on plasma can be used interchangeably with existing predicate platforms in South Africa. Whole blood and DBS testing requires further investigation, but polyvalency of the GeneXpert offers a solution to extending VL testing services.
Journal Article