Modelling CD4 reagent usage across a national hierarchal network of laboratories in South Africa

Background

The National Health Laboratory Service is mandated to deliver cost-effective and efficient diagnostic services across South Africa. Their mandate is achieved by a network of laboratories ranging from centralised national laboratories to distant rural facilities.

Objective

This study aimed to establish a model of CD4 reagent utilisation as an independent measure of laboratory efficiency.

Methods

The efficiency percentage was defined as finished goods (number of reportable results) over raw materials (number of reagents supplied) for 47 laboratories in nine provinces (both anonymised) for 2019. The efficiency percentage at national and provincial levels was calculated and compared to the optimal efficiency percentage derived using pre-set assumptions. Comparative laboratory analysis was conducted for the provinces with the best and worst efficiency percentages. The possible linear relationship between the efficiency percentage and call-outs, days lost, referrals, and turn-around time was assessed.

Results

Data are reported for 2 806 799 CD4 tests, with an overall efficiency percentage of 84.5% (optimal of 84.98%). The efficiency percentage varied between 75.7% and 87.7% between provinces, while within the laboratory it ranged from 66.1% to 111.5%. Four laboratories reported an efficiency percentage ranging from 67.8% to 85.7%. No linear correlation was noted between the efficiency percentage, call-outs, days lost, and turn-around time performance.

Conclusion

Reagent efficiency percentage distinguished laboratories into different utilisation levels irrespective of their CD4 service level. This parameter is an additional independent indicator of laboratory performance, with no relationship with any contributing factors tested, that can be implemented across pathology disciplines for monitoring reagent utilisation.

What this study adds

This study provides an objective methodology to assess reagent utilisation as an independent measure of laboratory efficiency. This model could be applied to all routine pathology services.

Newly implemented community CD4 service in Tshwaragano, Northern Cape province, South Africa, positively impacts result turn-around time

Background

The Northern Cape is South Africa’s largest province with an HIV prevalence of 7.1% versus a 13.5% national prevalence. CD4 testing is provided at three of five National Health Laboratory Service district laboratories, each covering a 250 km precinct radius. Districts without a local service report prolonged CD4 turn-around times (TAT).

Objective

This study documented the impact of a new CD4 laboratory in Tshwaragano in the remote John Taolo Gaetsewe district of the Northern Cape, South Africa.

Methods

CD4 test volumes and TAT (total, pre-analytical, analytical, and post-analytical) data for the Northern Cape province were extracted for June 2018 to October 2019. The percentage of CD4 results within the stipulated 40-h TAT cut-off and the median and 75th percentiles of all TAT parameters were calculated. Pre-implementation, samples collected at Tshwaragano were referred to Kimberley or Upington, Northern Cape, South Africa.

Results

Pre-implementation, 95.4% of samples at Tshwaragano were referred to Kimberley for CD4 testing (36.3% of Kimberley’s test volumes). Only 7.5% of Tshwaragano’s total samples were referred post-implementation. The Tshwaragano laboratory’s CD4 median total TAT decreased from 24.7 h pre-implementation to 12 h post-implementation (p = 0.003), with > 95.0% of results reported within 40 h. The Kimberley laboratory workload decreased by 29.0%, and testing time significantly decreased from 10 h to 4.3 h.

Conclusion

The new Tshwaragano CD4 service significantly decreased local TAT. Upgrading existing community laboratories to include CD4 testing can alleviate provincial service load and improve local access, TAT and efficiency in the centralised reference laboratory.

Weekly laboratory turn-around time identifies poor performance masked by aggregated reporting

Background

High-level monthly, quarterly and annual turn-around time (TAT) reports are used to assess laboratory performance across the National Health Laboratory Service in South Africa. Individual laboratory performances are masked by aggregate TAT reporting across network of testing facilities.

Objective

This study investigated weekly TAT reporting to identify laboratory inefficiencies for intervention.

Methods

CD4 TAT data were extracted for 46 laboratories from the corporate data warehouse for the 2016/2017 financial period. The total TAT median, 75th percentile and percentage of samples meeting organisational TAT cut-off (90% within 40 hours) were calculated. Total TAT was reported at national, provincial and laboratory levels. Provincial TAT performance was classified as markedly or moderately poor, satisfactory and good based on the percentage of samples that met the cut-off. The pre-analytical, testing and result review TAT component times were calculated.

Results

Median annual TAT was 18.8 h, 75th percentile was 25 h and percentage within cut-off was 92% (n = 3 332 599). Corresponding 75th percentiles of component TAT were 10 h (pre-analytical), 22 h testing and 1.6 h review. Provincial 75th percentile TAT varied from 17.6 h to 34.1 h, with three good (n = 13 laboratories), four satisfactory (n = 24 laboratories) and two poor performers (n = 9 laboratories) provinces. Weekly TAT analysis showed 12/46 laboratories (28.6%) without outlier weeks, 31/46 (73.8%) with 1-10 outlier weeks and 3/46 (6.5%) with more than 10 (highest of 20/52 weeks) outlier weeks.

Conclusion

Masked TAT under-performances were revealed by weekly TAT analyses, identifying poorly performing laboratories needing immediate intervention; TAT component analyses identified specific areas for improvement.

Assessing late presentation for female adolescents and young women with HIV in 2019, South Africa

Background

South Africa has the biggest HIV epidemic in the world, with an estimated 7.1million people living with HIV in 2018. In 2016, women aged 15-24 contributed 37% of new infections. Poverty, low status, gender-based violence (GBV) and intergenerational relationships possibly contribute to this disparate HIV prevalence. The objective of this study was to describe very advanced HIV disease (CD4< count <100cells/µL) amongst 15-24 year old females by interrogating routine laboratory CD4 data.

Methods

Specimen level CD4 laboratory data of female patients aged 15-24 was extracted for the 2019 calendar year. Patients were categorized as adolescents (15-19) or young women (20-24), in age categories of (i) 15-16, (ii) 17-19, (iii) 20-21 and (iv) 22-24 years. Frequency tables were used to report test volumes and the percentage of samples with counts <100 cells/µl.

Results

Amongst 259 088 CD4 outcomes extracted, 5.4% of samples had counts <100 cells/µl, with 75.4% of samples from young women and 24.6% from adolescents. Most samples reported an age between 22-24 (52.2%), with the lowest proportion (5.8%) noted in 15-16 year olds. Median CD4 was 485 cells/µL, with medians of 490 and 470 cells/µl noted for young women and adolescents respectively. Review of the <100 cells/µl group revealed a median of 43 cells/µL, with 38 and 46 cells/µL reported for young women and adolescents respectively. There was no significant association between the median CD4 and age category. Very advanced HIV disease by age categories of 15-16, 17-19, 20-21 and 22-24, comprised 7.0%, 5.6%, 5.0% and 5.3% respectively.

Conclusions

This study demonstrated unacceptable rates of very advanced HIV disease in female adolescents and young women, suggesting HIV seroconversion as teenagers or younger. Evidence-based specific health care interventions for these girls are urgently required, including tailoring social services and health facilities to secure the sexual health of girls and young women.

Key messages

Very advanced HIV disease presentation in female adolescents is unacceptably high. Young women and adolescents with late presentation.

A Preliminary Assessment of Skin Microbiome Diversity of Zebrafish (Danio rerio): South African Pet Shop Fish

The zebrafish (Danio rerio) is a well-known model organism used in an array of scientific research fields. Many microbiome studies conducted on fishes have focused on gut microbiome diversity. To our knowledge, no investigations into the skin microbiome diversity of pet shop zebrafish have been performed. In this pilot study we aimed to assess the microbiome diversity composition of different groups of zebrafish housed at the Department of Genetics, University of the Free State, South Africa. These fish originated from pet shops located in Bloemfontein, South Africa. We investigated the skin microbiome diversity between wild-type zebrafish and the well-known leopard colour morph. The microbiome compositions between zebrafish sexes were also assessed. No significant differences were observed between colour morphs. A core microbiome was identified for the zebrafish housed at our laboratories. Cetobacterium was significantly more abundant in females compared to males, with Limnobacter more abundant in males. Both these genera are known components of fish microbiomes, including zebrafish. The precise reason for this link should be further investigated. This research adds to the growing knowledge base linked to aquatic microbiome structure in different habitats.

Using laboratory data to categorise CD4 laboratory turn-around-time performance across a national programme

Background and objective

The National Health Laboratory Service provides CD4 testing through an integrated tiered service delivery model with a target laboratory turn-around time (TAT) of 48 h. Mean TAT provides insight into national CD4 laboratory performance. However, it is not sensitive enough to identify inefficiencies of outlying laboratories or predict the percentage of samples meeting the TAT target. The aim of this study was to describe the use of the median, 75th percentile and percentage within target of laboratory TAT data to categorise laboratory performance.

Methods

Retrospective CD4 laboratory data for 2015–2016 fiscal year were extracted from the corporate data warehouse. The laboratory TAT distribution and percentage of samples within the 48 h target were assessed. A scatter plot was used to categorise laboratory performance into four quadrants using both the percentage within target and 75th percentile TAT. The laboratory performance was labelled good, satisfactory or poor.

Results

TAT data reported a positive skew with a mode of 13 h and a median of 17 h and 75th percentile of 25 h. Overall, 93.2% of CD4 samples had a laboratory TAT of less than 48 h. 48 out of 52 laboratories reported good TAT performance, i.e. percentage within target > 85% and 75th percentile ≤ 48 h, with two categorised as satisfactory (one parameter met), and two as poor performing laboratories (failed both parameters).

Conclusion

This study demonstrated the feasibility of utilising laboratory data to categorise laboratory performance. Using the quadrant approach for TAT data, laboratories that need interventions can be highlighted for root cause analysis assessment.

Cryptococcal antigen positivity combined with the percentage of HIV-seropositive samples with CD4 counts <100 cells/μl identifies districts in South Africa with advanced burden of disease

Introduction

Cryptococcal meningitis (CM) is an opportunistic fungal disease with a high mortality among HIV-positive patients with severe immunosuppression (CD4 count <100 cells/μl). Reflexed screening for cryptococcal antigen (CrAg) in remnant blood samples was initially piloted at selected CD4 testing laboratories of the National Health Laboratory Service (NHLS) prior to the implementation of a national screening programme using a lateral flow assay (LFA) (IMMY, Norman, OK, USA). The aim of this study was to assess CrAg positivity nationally, per province and district in combination with the percentage of CD4 samples tested with a CD4 count <100 cells/μl to identify areas with advanced HIV/CrAg disease burden.

Methods

CrAg and CD4 laboratory result data were extracted from the NHLS corporate data warehouse. Monthly test volumes were used to assess CrAg test volumes and coverage, while bubble charts were used to display the relationship between CD4 <100 cells/μl, CrAg positivity and number of positive CrAg samples by district. ArcGIS software was used to spatially report CrAg positivity.

Results

CrAg screening coverage was stable at around 96% after November 2016. Samples with a CD4 <100 cell/μl and CrAg positivity were also stable over the study period at 10% and ~5% respectively. The highest CrAg positivity was reported for the Kwa-Zulu Natal province (7.3%), which also had the lowest percentage of samples with a CD4 <100 cells/μl (7.2%). Uthungulu and Umkhanyakude districts had the highest CrAg positivity (9.3% and 8.9% respectively). Ethekwini and Johannesburg Metro districts contributed to 22% of the total number of CrAg-positive samples tested across South Africa for the period reported.

Conclusion

Existing CD4 testing services were used to rapidly scale up CrAg reflex testing in South Africa. Districts with advanced HIV and CrAg disease burden were identified that need further investigation of patient management interventions.

Platelet Aging In Vivo Is Associated with Activation of Apoptotic Pathways: Studies in a Model of Suppressed Thrombopoiesis in Dogs

The mechanism(s) involved in the clearance of senescent platelets are largely unknown. We have recently demonstrated that platelet aging in vivo is associated with loss of membrane phospholipid asymmetry, a universal phenomenon in cells undergoing apoptosis. Thus, we postulated that senescent platelets may exhibit programmed cell death changes, which may trigger their removal from circulation. Since platelets contain the apoptosis machinery as well as mitochondria, a key organelle in the regulation of apoptosis, we studied the appearance of apoptotic-like changes during platelet aging in vivo. To investigate this, we assessed changes in mitochondrial membrane potential (Δψ) in circulating canine platelets during decline in platelet count after suppression of thrombopoiesis by estradiol injection, a validated model to obtain circulating platelets of increasing mean age. Phosphatidylserine (PS) exposure was determined by flow cytometry by binding of FITC-labeled annexin V. Mitochondrial Δψ was studied with the cationic lipophilic dye DIOC6 (3) and the J-aggregate-forming cation JC-1 and analysis by flow cytometry. The proportion of platelets with exposed PS rose significantly with age, from 2.88% before to 6.7%, 8 days after estradiol injection. By flow cytometry it was demonstrated a significant decreased in DIOC6 (3) fluorescence (median fluorescence intensity 791 ± 98 vs 567 ± 102 day 0 vs day 8 post injection of estradiol, respectively; n: 11; p <0.01), consistent with mitochondrial Δψ collapse. JC-1 has the unique property of forming J-aggregates under high mitochondrial Δψ (red fluorescence, FL2) whereas the monomeric form fluoresces in green (FL1). Aged platelets in vivo, loaded with JC-1, exhibited a significant increase in FL1/FL2 ratio (2.5 ± 1.7 vs 4.7 ± 1.6, day 0 vs day 8 post injection of estradiol, respectively; n: 13; p <0.05), confirming the mitochondrial Δψ alteration.

The results show that platelet aging in vivo is associated with a decrease in mitochondrial Δψ and PS exposure. In conclusion, our data provide for the first time, evidence that platelet senescence is associated with changes characteristics of apoptosis, which may promote their removal from circulation.

The Effect of Monoclonal Anti-human-platelet Antibodies on Platelet Kinetics in a Baboon Model: IgG Subclass Dependency

We assessed the in vivo effect of six intact anti-human antiplatelet antibodies of two major IgG subclasses on platelet kinetics in baboons. Five of the six antibodies tested caused thrombocytopenia of varying degree when injected at a precalculated threshold value. An agglutinating IgG1 antibody (MA-8L4A12) caused a long-lasting, mild thrombocytopenia with a predominant uptake of radiolabelled platelets in the spleen, while the four IgG2 antibodies tested (MA-13G8E1, MA-2M5A6, MA-21K2E8 and MA-22M10) caused a severe, transient thrombocytopenia with uptake of platelets in the liver. Two of the IgG2 antibodies (MA-13G8E1 and MA-2M5A6) caused platelet activation and aggregation in vitro, whilst the other two did not elicit a platelet aggregation response. The platelet survival time was shortened with all five of the thrombocytopenia-inducing antibodies, while only one antibody (MA-2M5A6) had a significant effect on the bleeding time. This study indicates that the IgG subclasss may be a determining factor in the outcome of platelet sequestration in immune-induced thrombocytopenia.

Performance verification of the new fully automated Aquios flow cytometer PanLeucogate (PLG) platform for CD4-T-lymphocyte enumeration in South Africa

BACKGROUND

The National Health Laboratory Service (NHLS) offers wide-scale CD4 testing through a network of laboratories in South Africa. A new "load and go" cytometer (Aquios CL, Beckman Coulter), developed with a PLG protocol, was validated against the predicate PLG method on the Beckman Coulter FC500 MPL/CellMek platform.

METHODS

Remnant routine EDTA blood CD4 reference results were compared to results from two Aquios/PLG instruments (n = 205) and a further n = 1885 samples tested to assess daily testing capacity. Reproducibility was assessed using ImmunotrolTM and patient samples with low, medium, high CD4 counts. Data was analyzed using GraphPad software for general statistics and Bland-Altman (BA) analyses. The percentage similarity (%Sim) was used to measure the level of agreement (accuracy) of the new platform versus the predicate and variance (%SimCV) reported to indicate precision of difference to predicate.

RESULTS

205 samples were tested with a CD4 count range of 2-1228 cells/μl (median 365cells/μl). BA analysis revealed an overall -40.5±44.0cells/μl bias (LOA of 126.8 to 45.8cells/μl) and %Sim showing good agreement and tight precision to predicate results (94.83±5.39% with %SimCV = 5.69%). Workflow analysis (n = 1885) showed similar outcomes 94.9±8.9% (CV of 9.4%) and 120 samples/day capacity. Excellent intra-instrument reproducibility was noted (%Sim 98.7±2.8% and %SimCV of 2.8%). 5-day reproducibility using internal quality control material (Immunotrol™) showed tight precision (reported %CV of 4.69 and 7.62 for Normal and Low material respectively) and instrument stability.

CONCLUSION

The Aquios/PLG CD4 testing platform showed clinically acceptable result reporting to existing predicate results, with good system stability and reproducibility with a slight negative but precise bias. This system can replace the faded XL cytometers in low- to medium volume CD4 testing laboratories, using the standardized testing protocol, with better staff utilization especially where technical skills are lacking. Central monitoring of on-board quality assessment data facilitates proactive maintenance and networked instrument performance monitoring.

Performance Evaluation of the Becton Dickinson FACSPresto™ Near-Patient CD4 Instrument in a Laboratory and Typical Field Clinic Setting in South Africa

Background

The BD-FACSPresto^™ CD4 is a new, point-of-care (POC) instrument utilising finger-stick capillary blood sampling. This study evaluated its performance against predicate CD4 testing in South Africa.

Methods

Phase-I testing: HIV+ patient samples (n = 214) were analysed on the Presto^™ under ideal laboratory conditions using venous blood. During Phase-II, 135 patients were capillary-bled for CD4 testing on FACSPresto^™, performed according to manufacturer instruction. Comparative statistical analyses against predicate PLG/CD4 method and industry standards were done using GraphPad Prism 6. It included Bland-Altman with 95% limits of agreement (LOA) and percentage similarity with coefficient of variation (%CV) analyses for absolute CD4 count (cells/μl) and CD4 percentage of lymphocytes (CD4%).

Results

In Phase-I, 179/217 samples yielded reportable results with Presto^™ using venous blood filled cartridges. Compared to predicate, a mean bias of 40.4±45.8 (LOA of -49.2 to 130.2) and %similarity (%CV) of 106.1%±7.75 (7.3%) was noted for CD4 absolute counts. In Phase-2 field study, 118/135 capillary-bled Presto^™ samples resulted CD4 parameters. Compared to predicate, a mean bias of 50.2±92.8 (LOA of -131.7 to 232) with %similarity (%CV) 105%±10.8 (10.3%), and 2.87±2.7 (LOA of -8.2 to 2.5) with similarity of 94.7±6.5% (6.83%) noted for absolute CD4 and CD4% respectively. No significant clinical differences were indicated for either parameter using two sampling methods.

Conclusion

The Presto^™ produced remarkable precision to predicate methods, irrespective of venous or capillary blood sampling. A consistent, clinically insignificant over-estimation (5–7%) of counts against PLG/CD4 and equivalency to FACSCount^™ was noted. Further field studies are awaited to confirm longer-term use.

Platelet aging in vivo is associated with activation of apoptotic pathways: studies in a model of suppressed thrombopoiesis in dogs

The mechanism(s) involved in the clearance of senescent platelets are largely unknown. We have recently demonstrated that platelet aging in vivo is associated with loss of membrane phospholipid asymmetry, a universal phenomenon in cells undergoing apoptosis. Thus, we postulated that senescent platelets may exhibit programmed cell death changes. which may trigger their removal from circulation. Since platelets contain the apoptosis machinery as well as mitochondria, a key organelle in the regulation of apoptosis, we studied the appearance of apoptotic-like changes during platelet aging in vivo. To investigate this, we assessed changes in mitochondrial membrane potential (deltapsi) in circulating canine platelets during decline in platelet count after suppression of thrombopoiesis by estradiol injection, a validated model to obtain circulating platelets of increasing mean age. Phosphatidylserine (PS) exposure was determined by flow cytometry by binding of FITC-labeled annexin V. Mitochondrial deltapsi was studied with the cationic lipophilic dye DIOC6 (3) and the J-aggregate-forming cation JC-1 and analysis by flow cytometry. The proportion of platelets with exposed PS rose significantly with age, from 2.88% before to 6.7%, 8 days after estradiol injection. By flow cytometry it was demonstrated a significant decreased in DIOC6 (3) fluorescence (median fluorescence intensity 791+/-98 vs 567+/-102 day 0 vs day 8 post injection of estradiol, respectively; n: 11; p <0.01), consistent with mitochondrial deltapsi collapse. JC-1 has the unique property of forming J-aggregates under high mitochondrial deltapsi (red fluorescence, FL2) whereas the monomeric form fluoresces in green (FL1). Aged platelets in vivo, loaded with JC-1, exhibited a significant increase in FL1/FL2 ratio (2.5+/-1.7 vs 4.7+/-1.6, day 0 vs day 8 post injection of estradiol, respectively; n: 13; p <0.05), confirming the mitochondrial deltapsi alteration. The results show that platelet aging in vivo is associated with a decrease in mitochondrial deltapsi and PS exposure. In conclusion, our data provide for the first time, evidence that platelet senescence is associated with changes characteristics of apoptosis, which may promote their removal from circulation.

The effect of monoclonal anti-human-platelet antibodies on platelet kinetics in a baboon model: IgG subclass dependency

We assessed the in vivo effect of six intact anti-human antiplatelet antibodies of two major IgG subclasses on platelet kinetics in baboons. Five of the six antibodies tested caused thrombocytopenia of varying degree when injected at a precalculated threshold value. An agglutinating IgG1 antibody (MA-8L4A12) caused a long-lasting, mild thrombocytopenia with a predominant uptake of radiolabelled platelets in the spleen, while the four IgG2 antibodies tested (MA-13G8E1, MA-2M5A6, MA-21K2E8 and MA-22M10) caused a severe, transient thrombocytopenia with uptake of platelets in the liver. Two of the IgG2 antibodies (MA-13G8E1 and MA-2M5A6) caused platelet activation and aggregation in vitro, whilst the other two did not elicit a platelet aggregation response. The platelet survival time was shortened with all five of the thrombocytopenia-inducing antibodies, while only one antibody (MA-2M5A6) had a significant effect on the bleeding time. This study indicates that the IgG subclasss may be a determining factor in the outcome of platelet sequestration in immune-induced thrombocytopenia.