Lindi M. Coetzee

Performance evaluation of the Pima™ point-of-care CD4 analyser using capillary blood sampling in field tests in South Africa

BackgroundPoint-of-care CD4 testing can provide immediate CD4 reporting at HIV-testing sites. This study evaluated performance of capillary blood sampling using the point-of-care Pima™ CD4 device in representative primary health care clinics doing HIV testing.MethodsPrior to testing, prescribed capillary-sampling and instrument training was undertaken by suppliers across all sites. Matching venous EDTA samples were drawn throughout for comparison to laboratory predicate methodology (PLG/CD4). In Phase I, Pima™ cartridges were pipette-filled with EDTA venous blood in the laboratory (N = 100). In Phase II (N = 77), Pima™ CD4 with capillary sampling was performed by a single operator in a hospital-based antenatal clinic. During subsequent field testing, Pima™ CD4 with capillary sampling was performed in primary health care clinics on HIV-positive patients by multiple attending nursing personnel in a rural clinic (Phase-IIIA, N = 96) and an inner-city clinic (Phase-IIIB, N = 139).ResultsPima™ CD4 compared favourably to predicate/CD4 when cartridges were pipette-filled with venous blood (bias -17.3 ± STDev = 36.7 cells/mm3; precision-to-predicate %CV < 6%). Decreased precision of Pima™ CD4 to predicate/CD4 (varying from 17.6 to 28.8%SIM CV; mean bias = 37.9 ± STDev = 179.5 cells/mm3) was noted during field testing in the hospital antenatal clinic. In the rural clinic field-studies, unacceptable precision-to-predicate and positive bias was noted (mean 28.4%SIM CV; mean bias = +105.7 ± STDev = 225.4 cells/mm3). With additional proactive manufacturer support, reliable performance was noted in the subsequent inner-city clinic field study where acceptable precision-to-predicate (11%SIM CV) and less bias of Pima™ to predicate was shown (BA bias ~11 ± STDev = 69 cells/mm3).ConclusionsVariable precision of Pima™ to predicate CD4 across study sites was attributable to variable capillary sampling. Poor precision was noted in the outlying primary health care clinic where the system is most likely to be used. Stringent attention to capillary blood collection technique is therefore imperative if technologies like Pima™ are used with capillary sampling at the POC. Pima™ CD4 analysis with venous blood was shown to be reproducible, but testing at the point of care exposes operators to biohazard risk related to uncapping vacutainer samples and pipetting of blood, and is best placed in smaller laboratories using established principles of Good Clinical Laboratory Practice. The development of capillary sampling quality control methods that assure reliable CD4 counts at the point of care are awaited.

Large‐scale affordable Panleucogated CD4+ testing with proactive internal and external quality assessment: In support of the South African national comprehensive care, treatment and management programme for HIV and AIDS

In order to expand the treatment of human immunodeficiency virus‐1 (HIV) infected patients in Africa, millions will require cost‐effective CD4 counts. Supporting laboratories therefore, need to move away from crisis management and haphazard practices to organized pathology services. The authors reviewed the performance of the simplified single platform (SP) PanLeucogated (PLG) CD4 methodology, introduced into 52 laboratories across the South African National Health Laboratory Service (SA‐NHLS), with a proactive approach to training, internal quality control (IQC), and external quality assessment (EQA).

CD8/CD38 activation yields important clinical information of effective antiretroviral therapy: Findings from the first year of the CIPRA‐SA cohort

The affordable, reliable, and simplified flow cytometric method on single platform with 2‐color (CD45+, CD4+) Panleucogating (PLG‐CD4) is used to monitor HIV+ patients on antiretroviral therapy (ART) in South Africa (SA). Viral load (VL) assays are also used to monitor response to ART but are labor‐intensive with costs that, in the long run, may remain unsustainable. Cheaper and quicker alternatives to VL such as CD38 tests on CD8+ T cells may therefore play a role in securing the continuation of ART programs in high‐volume resource‐restricted settings.

Local reference ranges for full blood count and CD4 lymphocyte count testing

OBJECTIVE Recent advances in full blood count and CD4 technology, coupled with the changing population demographics of the Gauteng region, have necessitated reevaluation of the reference ranges currently in use. METHODS A cross-sectional study of 631 female and 88 male HIV-negative participants from the Gauteng region was performed. Full blood count, automated differential and CD4 count analyses were done using the latest internationally accepted technology. Reference ranges were compiled from the 2.5th and 97.5th percentiles for both male and female participant groups, and gender and ethnic comparisons calculated by non-parametric tests. RESULTS Results of 41 females were removed from the statistical analysis because their results were suggestive of possible anaemia. Full blood count reference interval comparison confirmed gender-specific differences in red blood cell and platelet parameters. Ethnic-specific differences were found for some red blood cell parameters in the black female cohort. In addition, black males and females both generally had lower neutrophil and higher lymphocyte counts than a combined Asian/Caucasian/coloured ethnic group. CONCLUSION Comparison of the currently calculated reference ranges with published data and reference values in use indicated that a separate ethnic-specific reference range should be introduced for the percentage/absolute neutrophil count and percentage lymphocytes. In addition, locally derived reference ranges for red cell distribution width (RDW) and CD4 percentage of lymphocytes should be implemented for routine diagnostic testing.

From research tool to routine test: CD38 monitoring in HIV patients

CD38 expression on CD8+ T lymphocytes in HIV‐infected patients is monitored by flow cytometry (FCM). There is however no consensus re CD38 protocols, analyses or result reporting within/between laboratories. Internal quality control measures (QC) were established for a standardized CD38 protocol and a system proposed for reporting CD38 fluctuation in longitudinal HIV+ patient monitoring.

An integrated tiered service delivery model (ITSDM) based on local CD4 testing demands can improve turn-around times and save costs whilst ensuring accessible and scalable CD4 services across a national programme.

Background The South African National Health Laboratory Service (NHLS) responded to HIV treatment initiatives with two-tiered CD4 laboratory services in 2004. Increasing programmatic burden, as more patients access anti-retroviral therapy (ART), has demanded extending CD4 services to meet increasing clinical needs. The aim of this study was to review existing services and develop a service-model that integrated laboratory-based and point-of-care testing (POCT), to extend national coverage, improve local turn-around/(TAT) and contain programmatic costs. Methods NHLS Corporate Data Warehouse CD4 data, from 60–70 laboratories and 4756 referring health facilities was reviewed for referral laboratory workload, respective referring facility volumes and related TAT, from 2009–2012. Results An integrated tiered service delivery model (ITSDM) is proposed. Tier-1/POCT delivers CD4 testing at single health-clinics providing ART in hard-to-reach areas (<5 samples/day). Laboratory-based testing is extended with Tier-2/POC-Hubs (processing ≤30–40 CD4 samples/day), consolidating POCT across 8–10 health-clinics with other HIV-related testing and Tier-3/‘community’ laboratories, serving ≤40 health-clinics, processing ≤150 samples/day. Existing Tier-4/‘regional’ laboratories serve ≤100 facilities and process <350 samples/day; Tier-5 are high-volume ‘metro’/centralized laboratories (>350–1500 tests/day, serving ≥200 health-clinics). Tier-6 provides national support for standardisation, harmonization and quality across the organization. Conclusion The ITSDM offers improved local TAT by extending CD4 services into rural/remote areas with new Tier-3 or Tier-2/POC-Hub services installed in existing community laboratories, most with developed infrastructure. The advantage of lower laboratory CD4 costs and use of existing infrastructure enables subsidization of delivery of more expensive POC services, into hard-to-reach districts without reasonable access to a local CD4 laboratory. Full ITSDM implementation across 5 service tiers (as opposed to widespread implementation of POC testing to extend service) can facilitate sustainable ‘full service coverage’ across South Africa, and save>than R125 million in HIV/AIDS programmatic costs. ITSDM hierarchical parental-support also assures laboratory/POC management, equipment maintenance, quality control and on-going training between tiers.

Performance of the PointCare NOW System for CD4 Counting in HIV Patients Based on Five Independent Evaluations

Introduction Point-of-care (POC) CD4 testing can improve access to treatment by enabling decentralization and reducing patient loss-to-follow-up. As new POC CD4 technologies become available, their performance should be assessed before widespread deployment. This study reports the findings of five independent evaluations of the PointCare NOW CD4 system. Materials/Methods Evaluations were conducted in Southern Africa (Mozambique, South Africa) and North America (Canada, USA). 492 blood samples (55 from HIV-negative blood donors and 437 from HIV-infected patients, including 20 children aged between 12 and 59 months) were tested with both the PointCare NOW and reference flow cytometry instruments. Assessment of bias, precision and levels of clinical misclassification for absolute and percent CD4 count was conducted. Results PointCare NOW significantly overestimated CD4 absolute counts with a mean relative bias of +35.0%. Bias was greater in samples with CD4 counts below ≤350cells/µl (+51.3%) than in the CD4 >350cells/µl stratum (15.1%). Bias in CD4% had a similar trend with an overall relative mean bias of +25.6% and a larger bias for low CD4 stratum (+40.2%) than the higher CD4 stratum (+5.8%). Relative bias for CD4% in children was −6.8%. In terms of repeatability, PointCare NOW had a coefficient of variation of 11%. Using a threshold of 350cells/µl, only 47% of patients who qualified for antiretroviral therapy with reference CD4 testing, would have been eligible for treatment with PointCare NOW test results. This was 39% using a 200cells/µl threshold. Agreement with infant samples was higher, with 90% qualifying at a 25% eligibility threshold. Conclusion The performance of the PointCare NOW instrument for absolute and percent CD4 enumeration was inadequate for HIV clinical management in adults. In children, the small sample size was not large enough to draw a conclusion. This study also highlights the importance of independent evaluation of new diagnostic technology platforms before deployment.

Estimating Implementation and Operational Costs of an Integrated Tiered CD4 Service including Laboratory and Point of Care Testing in a Remote Health District in South Africa

Background An integrated tiered service delivery model (ITSDM) has been proposed to provide ‘full-coverage’ of CD4 services throughout South Africa. Five tiers are described, defined by testing volumes and number of referring health-facilities. These include: (1) Tier-1/decentralized point-of-care service (POC) in a single site; Tier-2/POC-hub servicing processing <30–40 samples from 8–10 health-clinics; Tier-3/Community laboratories servicing ∼50 health-clinics, processing <150 samples/day; high-volume centralized laboratories (Tier-4 and Tier-5) processing <300 or >600 samples/day and serving >100 or >200 health-clinics, respectively. The objective of this study was to establish costs of existing and ITSDM-tiers 1, 2 and 3 in a remote, under-serviced district in South Africa. Methods Historical health-facility workload volumes from the Pixley-ka-Seme district, and the total volumes of CD4 tests performed by the adjacent district referral CD4 laboratories, linked to locations of all referring clinics and related laboratory-to-result turn-around time (LTR-TAT) data, were extracted from the NHLS Corporate-Data-Warehouse for the period April-2012 to March-2013. Tiers were costed separately (as a cost-per-result) including equipment, staffing, reagents and test consumable costs. A one-way sensitivity analyses provided for changes in reagent price, test volumes and personnel time. Results The lowest cost-per-result was noted for the existing laboratory-based Tiers- 4 and 5 (

A model for continuous quality control incorporating sample‐to‐sample assessment of optical alignment, fluorescence sensitivity, and volumetric operation of flow cytometers

6.24 and

Screening HIV-Infected Patients with Low CD4 Counts for Cryptococcal Antigenemia prior to Initiation of Antiretroviral Therapy: Cost Effectiveness of Alternative Screening Strategies in South Africa

5.37 respectively), but with related increased LTR-TAT of >24–48 hours. Full service coverage with TAT <6-hours could be achieved with placement of twenty-seven Tier-1/POC or eight Tier-2/POC-hubs, at a cost-per-result of