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Subject: search.filters.subject.Charlotte Maxeke Johannesburg Academic Hospital

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    Rationalising laboratory workflow to improve the efficiency of diagnostic service delivery: A critical review of haematological malignancies by flow cytometric immunophenotyping at the Charlotte Maxeke Johannesburg Academic Hospital
    (University of the Witwatersrand, Johannesburg, 2024) Naidoo, Maynolia; Glencross, Debbie
    The 2006 Bethesda medical indications guideline provides concise indications for flow cytometric immunophenotyping (FCI), to enable rationalising a decision for sample processing. The local practice of processing every sample received for FCI places an enormous burden on the resources of the laboratory, and leads to unnecessary expenditure for state health. A ‘triage’ process based on the current Bethesda medical indications guideline may be beneficial in developing countries. The aim of this study was to determine how the implementation of a triage process would impact on the diagnostic service delivery, and the ability to detect or miss disease. A retrospective review of 500 bone marrow aspirate (BMA) samples submitted for FCI analysis was performed from October to December 2019. The sensitivity, specificity, and predictive values of the BMA cytomorphology against the FCI outcomes (‘test-all’) were determined. Thereafter, the Bethesda medical indications guideline was retrospectively applied to the same data set (‘triage’), to compare the decision to process or not to process samples, against objective evidence of disease in various BMA investigations. After exclusion of inadequate quality samples that preclude comparison, 429 ‘test-all’ and 455 triage cases were evaluated. The ‘test-all’ analysis revealed a 97.1% sensitivity and 89.8% specificity, with a 64.1% positive predictive value (PPV) but striking 99.4% negative predictive value (NPV). The triage was largely effective in identifying cases with disease, revealing a 100% sensitivity and 83.3% specificity, with a PPV of 32.5% and very high NPV of 93.8%. Without impacting clinical outcomes, the implementation of a triage process can reduce the burden of FCI testing by 18%. Preliminary cytomorphological review of the accompanying BMA is strongly recommended as an additional step to improve the overall PPV of the triage, while safely reducing unnecessary FCI sample processing in a further 56% of cases. The implementation of a triage process with modifications for local use in flow cytometry laboratories, would enable the appropriate rationalisation of resources, improve the cost- effectiveness, and overall diagnostic service delivery in developing countries like Sub-Saharan Africa
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    Comparison of second and third generation parathyroid hormone (PTH) assays performed at Charlotte Maxeke Johannesburg Academic Hospital – Are they fit for purpose?
    (University of the Witwatersrand, Johannesburg, 2023-11) Nhlapo, Nokuthula; Jacob, Doreen; Maphayi, Mpho
    Background: Parathyroid hormone (PTH) measurement is crucial in the investigation of calcium and phosphate disorders and in the management of chronic kidney disease (CKD). Available PTH assays include second (intact PTH) and third generation (PTH 1-84) assays. Intact PTH assays are widely available and used for clinical guidelines but overestimate PTH in CKD. PTH 1-84 assays are more specific, but lack of standardisation has complicated clinical interpretation. The study aimed to compare the second and third generation assays to determine the difference in analytical performance and the effect on clinical interpretation. Methods: A method comparison was done on 481 patient samples with PTH requested at Charlotte Maxeke Johannesburg Academic Hospital. PTH was measured in each sample using both intact PTH and PTH 1-84 assays. Passing Bablok regression and Bland Altman plots were performed to determine method agreement and bias. Analytical performance was assessed using the European Federation of Clinical Chemistry and Laboratory Medicine biological variation specifications. Clinical performance was compared in the diagnosis of hypo- and hyperparathyroidism, and in predialysis and dialysis CKD based on current Kidney Disease Improving Global Outcomes guidelines. Results: Intact PTH had a higher median concentration than PTH 1-84 (9.93 vs 8.60 pmol/L, p<0.0001) but showed good correlation (r = 0.994 and p<0.0001). Regression analysis revealed significant systematic and proportional differences, with increased deviations at higher concentrations. The average bias was above allowable bias of 7.1%. Clinical interpretation of hypo- and hyperparathyroidism and predialysis and dialysis groups was unchanged. Conclusions: There was significant bias observed between the two PTH assays thus, they should not be used interchangeably. However, no significant changes in clinical interpretation were found when one assay was used over the other. The decision to use third over second generation PTH assay should consider the impact on clinical interpretation in the population.