Browsing by Author "Vreede, Helena"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Open Access
    Assessment of the effectiveness of electronic gatekeeping as a utilization management tool at Groote Schuur Hospital
    (2018) Bosman, Michelle; van der Watt, George; Omar, Fierdoz; Vreede, Helena
    BACKGROUND: Utilization management ensures the appropriateness of laboratory testing by reducing the performance of tests which can be reasonably avoided with no adverse effects for the patient. Electronic gatekeeping, a utilization management tool, was introduced at Groote Schuur in 2010. Criteria were based on the minimum retesting interval, healthcare location, level of experience and discipline of the requesting clinician and specific ICD-10 codes. METHODS: A retrospective observational study assessing the effectiveness of electronic gatekeeping at Groote Schuur Hospital (Cape Town, South Africa), by comparing the test request volumes by using absolute test numbers and pre-defined ratios in the year prior to gatekeeping, to the two years following implementation. A secondary aim is to apply selected ratios to the other national academic hospitals to determine the potential for cost saving. RESULTS: At the medical wards of Groote Schuur Hospital there was an overall decrease in number and cost of tests of 24% per inpatient day for 2011. The most dramatic difference in cost is seen for chloride (91%) followed by HbA1c (90%), FT3 (89%) and CRP (82%). The application of ratios to Groote Schuur Hospital show a decrease in 2011 in all ratios apart from PCT: FBC+WCC (0.003 vs 0.002) and Mg: Ca (0.86 vs 0.84). AST: ALT remained the same at 0.55. This suggests overall effectiveness of the eGK rules although there is ongoing panel requesting. If the GSH eGK rules were to be applied at all other national academic hospitals, it could translate into a potential cost saving of $13 411 873.96 (R103 196 838.80) per annum. CONCLUSIONS: Electronic gatekeeping is an effective utilization management tool at Groote Schuur Hospital. It is relatively easy to implement and manage, and when combined with additional tools has the potential to result in larger reductions of unnecessary tests, cost savings and improved patient outcome.
  • No Thumbnail Available
    Item
    Open Access
    Determination of reference intervals and decision limits for thyroid stimulating hormone and thyroxine on cord blood samples
    (2025) Mahomed, Mariam; Rusch, Jody; Vreede, Helena
    Background: Congenital hypothyroidism (CH) is a significant health concern globally, with severe consequences if left untreated. Newborn screening (NBS) programs play a pivotal role in early detection and intervention of CH. However, due to resource constraints, South Africa lacks a national NBS program. This study aimed to establish reference intervals for thyroid stimulating hormone (TSH) and free thyroxine (FT4) in cord blood, as well as to compare the previous TSH radioimmunoassay with the current electrochemiluminescence immunoassay. Methods: Utilizing residual samples from the Peninsula Maternal and Neonatal Services (PMNS) CH Screening Program, this prospective study collected samples from uncomplicated pregnancies, resulting in 121 samples for reference interval analysis. Additionally, 14 samples within pathological ranges were selected, bringing the total for the method comparison study to 135. TSH and FT4 levels were determined by automated immunoassay on the Roche Cobas® 6000 analyser (Elecsys TSH and Elecsys FT4 III assays). The data analysis was performed following relevant CLSI guidelines (CLSI EP28-A3c and CLSI EP09-A3). Results: In the reference interval study, the mean birth weight was 3,211g (+/-387g). Non-parametric methodology yielded a TSH reference interval of 1.85 to 15.35 mIU/L and a free T4 reference interval of 13.0 to 20.4 pmol/L. The TSH method comparison study demonstrated strong agreement between the radioimmunoassay and electrochemiluminescence immunoassay (R-squared=0.98; Lin's CCC=0.97). Bland-Altman analysis revealed most points within the European Federation of Clinical Chemistry and Laboratory Medicine (EFLM) total allowable error goals for TSH, with RIA results showing a small positive bias. Conclusion: This study establishes reference intervals for cord blood TSH and FT4 in a South African context. Cord blood presents advantages for CH screening in resource-constrained settings, integrating with existing labour and delivery protocols while minimizing logistical challenges. The established intervals align with existing literature and methodologies, supporting their validity and applicability. Continued monitoring of the CH program and clinical outcomes is crucial for validating the study results in a clinical context, ensuring ongoing relevance and accuracy.
  • Thumbnail Image
    Item
    Open Access
    How South Africa Used National Cycle Threshold (Ct) Values to Continuously Monitor SARS-CoV-2 Laboratory Test Quality
    (Multidisciplinary Digital Publishing Institute, 2023-08-01) Scott, Lesley Erica; Hsiao, Nei-yuan; Dor, Graeme; Hans, Lucia; Marokane, Puleng; da Silva, Manuel Pedro; Preiser, Wolfgang; Vreede, Helena; Tsoka, Jonathan; Mlisana, Koleka; Stevens, Wendy Susan
    The high demand for SARS-CoV-2 tests but limited supply to South African laboratories early in the COVID-19 pandemic resulted in a heterogenous diagnostic footprint of open and closed molecular testing platforms being implemented. Ongoing monitoring of the performance of these multiple and varied systems required novel approaches, especially during the circulation of variants. The National Health Laboratory Service centrally collected cycle threshold (Ct) values from 1,497,669 test results reported from 6 commonly used PCR assays in 36 months, and visually monitored changes in their median Ct within a 28-day centered moving average for each assays’ gene targets. This continuous quality monitoring rapidly identified delayed hybridization of in the Allplex & trade; SARS-CoV-2 assay due to the Delta (B.1.617.2) variant; gene target failure in the TaqPath & trade; COVID-19 assay due to B.1.1.7 (Alpha) and the B.1.1.529 (Omicron); and recently gene delayed hybridization in the Xpress SARS-CoV-2 due to XBB.1.5. This near ;real-time; monitoring helped inform the need for sequencing and the importance of multiplex molecular nucleic acid amplification technology designs used in diagnostics for patient care. This continuous quality monitoring approach at the granularity of Ct values should be included in ongoing surveillance and with application to other disease use cases that rely on molecular diagnostics.
  • Thumbnail Image
    Item
    Open Access
    Validation of an adjusted calcium formula using the Roche calcium (NMBATPA) and albumin (BCG) methods at Groote Schuur Hospital
    (2017) Ndlovu, Mbali; Omar, Fierdoz; Vreede, Helena
    ABSTRACT: Validation of an adjusted calcium formula using the Roche calcium (NMBATPA) and albumin (BCG) methods at Groote Schuur Hospital Introduction: Most laboratories continue to adjust serum total calcium (tCa) concentration for serum albumin as a surrogate marker of calcium status, despite the availability of ionised calcium (iCa) measurement. Current recommendations by the Association for Clinical Biochemistry and Laboratory Medicine (ACB) advocate that laboratories should use formulae specific for their tCa and albumin methods and analytical platforms. The National Health Laboratory Service at Groote Schuur Hospital (GSH) undertook to investigate this recommendation. An adjusted calcium (aCa) formula specific for the Roche serum tCa and albumin methods was derived from 3131 patients. We investigated the validity and clinical utility of this locally derived aCa formula. Methods: The tCa, albumin and iCa were analysed in blood from 162 inpatients and outpatients at GSH. Corrected calcium (cCa) was calculated using the Payne cCa formula, and aCa was calculated with the new aCa formula. Patients were classified as hypo-, normoor hypercalcaemic using iCa, tCa, cCa and aCa measurements. Cohen's kappa statistic, loglinear and logistic regression models and interclass and concordance correlation coefficients were used to assess agreement between tCa, Payne cCa and aCa against iCa (gold standard). Agreement was further assessed according to renal status and albumin concentrations. Results: The aCa demonstrated good correlation with iCa, but its performance was not significantly better than tCa or Payne cCa in correctly classifying calcium status. Furthermore, albumin concentration was demonstrated to predict the performance of the calcium status classification by the aCa and cCa formulae, irrespective of renal status. Conclusion: The laboratory-specific aCa formula did not perform significantly better than tCa and the Payne cCa formula. This implies that aCa does not add value over tCa where iCa measurements are not readily available.