6 results on '"van der Westhuizen, Diederick"'
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2. Transfers between health facilities of people living with diabetes attending primary health care services in the Western Cape Province of South Africa: A retrospective cohort study.
- Author
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Odayar, Jasantha, Rusch, Jody, Dave, Joel A., Van Der Westhuizen, Diederick J., Mukonda, Elton, Lesosky, Maia, and Myer, Landon
- Subjects
PEOPLE with diabetes ,HEALTH facilities ,PRIMARY health care ,MEDICAL care ,HEALTH planning ,REPRODUCTIVE health services - Abstract
Objectives: Transfers between health facilities of people living with HIV attending primary health care (PHC) including hospital to PHC facility, PHC facility to hospital and PHC facility to PHC facility transfers occur frequently, affect health service planning, and are associated with disengagement from care and viraemia. Data on transfers among people living with diabetes attending PHC, particularly transfers between PHC facilities, are few. We assessed the transfer incidence rate of people living with diabetes attending PHC, and the association between transfers between PHC facilities and subsequent HbA1c values. Methods: We analysed data on HbA1c tests at public sector facilities in the Western Cape Province (2016–March 2020). Individuals with an HbA1c in 2016–2017 were followed‐up for 27 months and included in the analysis if ≥18 years at first included HbA1c, ≥2 HbA1cs during follow‐up and ≥1 HbA1c at a PHC facility. A visit interval was the duration between two consecutive HbA1cs. Successive HbA1cs at different facilities of any type indicated any transfer, and HbA1cs at different PHC facilities indicated a transfer between PHC facilities. Mixed effects logistic regression adjusted for sex, age, rural/urban facility attended at the start of the visit interval, disengagement (visit interval >14 months) and a hospital visit during follow‐up assessed the association between transfers between PHC facilities and HbA1c >8%. Results: Among 102,813 participants, 22.6% had ≥1 transfer of any type. Including repeat transfers, there were 29,994 transfers (14.4 transfers per 100 person‐years, 95% confidence interval [CI] 14.3–14.6). A total of 6996 (30.1%) of those who transferred had a transfer between PHC facilities. Visit intervals with a transfer between PHC facilities were longer (349 days, interquartile range [IQR] 211–503) than those without any transfer (330 days, IQR 182–422). The adjusted relative odds of an HbA1c ≥8% after a transfer between PHC facilities versus no transfer were 1.20 (95% CI 1.05–1.37). Conclusion: The volume of transfers involving PHC facilities requires consideration when planning services. Individuals who transfer between PHC facilities require additional monitoring and support. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
3. Development of a simple HPLC-UV method for determination of GFR by serum iohexol clearance
- Author
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van Der Westhuizen, Diederick J, Pillay, Joanne, and van der Watt, George
- Subjects
Medicine - Abstract
The glomerular filtration rate (GFR) is considered the best indicator of kidney function. Iohexol, a contrast agent, is currently considered to be a reference marker since it meets all the requirements of an ideal GFR marker. The aim of this study was to develop and validate a method for iohexol measurement using high performance liquid chromatography with ultraviolet detection (HPLCUV). The method developed includes a mobile phase with water and acetonitrile with a gradient of 5%-30% organic, a C18 analytical column (100 × 4.6 mm, 2.7 µm particle size) at a temperature of 40 °C and a flow rate of 0.5 ml/min. Serum samples were deproteinized by addition of perchloric acid (5%). The assay met the sensitivity cut-off with a mean signal-to-noise ratio of 17.2 at a level of 10 µg/mL iohexol. Mean recovery was 103.7% (CV=4.4%). The dilution experiment allowed for 5-times dilution up to iohexol levels of 500 µg/mL with an accuracy of 103.1% (CV=1.3%) For selectivity, no interfering endogenous compounds at the retention time of iohexol were observed. The matrix effect experiment showed a clinically acceptable variation at all concentration levels with a CV of the slopes of 2.7%. Stability of the stock solution was proven for at least 9 months at -80°C. Sample post-extraction stability was adequate at 84 hours. Interference testing yielded between -7% and -12% difference at 2% haemolysis and -9% to -13% difference at 10% lipaemia. With regards to these findings, this method is simple, specific, linear, precise and robust, which allows its application for the measurement of GFR in serum.
- Published
- 2023
4. Varicella‐zoster virus reactivation is frequently detected in HIV‐infected individuals presenting with stroke.
- Author
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Marais, Gert, Naidoo, Michelle, McMullen, Kate, Stanley, Alan, Bryer, Alan, van der Westhuizen, Diederick, Bateman, Kathleen, and Hardie, Diana Ruth
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VARICELLA-zoster virus ,VIRUS reactivation ,HERPES zoster ,HIV infections ,YOUNG adults ,HIV-positive persons ,VARICELLA-zoster virus diseases - Abstract
Infections are an underappreciated cause of stroke, particularly in young and immunocompromised individuals. Varicella‐zoster virus (VZV) reactivation, particularly ophthalmic zoster, has been linked to increased risk of stroke but diagnosing VZV‐associated cerebral vasculopathy is challenging as neither a recent zoster rash, nor detectable levels of VZV DNA are universally present at stroke presentation. Detection of VZV IgG in cerebrospinal fluid (CSF‐VZVG) presents a promising alternative, but requires evaluation of individual blood‐CSF dynamics, particularly in the setting of chronic inflammatory states such as HIV infection. Consequently, its use has not been broadly adopted as simple diagnostic algorithms are not available. In this study looking at young adults presenting with acute stroke, we used an algorithm that includes testing for both VZV nucleic acids and CSF‐VZVG which was corrected for blood‐CSF barrier dynamics and poly‐specific immune activation. We found that 13 of 35 (37%), including 7 with a positive CSF VZV PCR, young HIV‐infected adults presenting with stroke, 3 of 34 (9%) young HIV‐uninfected adults presenting with stroke, and 1 of 18 (6%) HIV‐infected nonstroke controls demonstrated evidence of central nervous system reactivation of VZV. Highlights: Current nucleic acid detection‐based methods are inadequate as a standalone test for detecting clinically relevant episodes of central nervous system varicella‐zoster virus reactivation (CVR).A diagnostic algorithm which includes the calculation of intrathecally produced varicella‐zoster virus (VZV) IgG concentration aids the detection of CVR in young patients with stroke.CVR was more common in HIV‐infected (37%) stroke patients than in HIV‐uninfected (9%) cases.In the absence of CVR, HIV‐positive status is associated with significantly lower levels of VZV‐specific IgG production in CSF.In contrast, intrathecally produced VZV IgG levels were significantly higher in HIV‐positive patients with evidence of recent CVR. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
5. Comparing the effectiveness and cost-effectiveness of alternative type 2 diabetes monitoring intervals in resource limited settings.
- Author
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Mukonda E, Lesosky M, Sithole S, van der Westhuizen DJ, Rusch JA, Levitt NS, Myers B, and Cleary S
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- Humans, South Africa, Markov Chains, Male, Female, Middle Aged, Quality of Life, Resource-Limited Settings, Diabetes Mellitus, Type 2 therapy, Diabetes Mellitus, Type 2 blood, Cost-Benefit Analysis, Glycated Hemoglobin analysis, Quality-Adjusted Life Years
- Abstract
Type 2 diabetes (T2D) represents a growing disease burden in South Africa. While glycated haemoglobin (HbA1c) testing is the gold standard for long-term blood glucose management, recommendations for HbA1c monitoring frequency are based on expert opinion. This study investigates the effectiveness and cost-effectiveness of alternative HbA1c monitoring intervals in the management of T2D. A Markov model with three health states (HbA1c <7%, HbA1c ≥ 7%, Dead) was used to estimate lifetime costs and quality-adjusted life years (QALYs) of alternative HbA1c monitoring intervals among patients with T2D, using a provider's perspective and a 3% discount rate. HbA1c monitoring strategies (three-monthly, four-monthly, six-monthly and annual tests) were evaluated with respect to the incremental cost-effectiveness ratio (ICER) assessing each comparator against a less costly, undominated alternative. The scope of costs included the direct medical costs of managing diabetes. Transition probabilities were obtained from routinely collected public sector HbA1c data, while health service utilization and health-related-quality-of-life (HRQoL) data were obtained from a local cluster randomized controlled trial. Other parameters were obtained from published studies. Robustness of findings was evaluated using one-way and probabilistic sensitivity analyses. A South African indicative cost-effectiveness threshold of USD2665 was adopted. Annual and lifetime costs of managing diabetes increased with HbA1c monitoring, while increased monitoring provides higher QALYs and life years. For the overall cohort, the ICER for six-monthly vs annual monitoring was cost-effective (USD23 22.37 per QALY gained), whereas the ICER of moving from six-monthly to three-monthly monitoring was not cost effective (USD6437.79 per QALY gained). The ICER for four-monthly vs six-monthly monitoring was extended dominated. The sensitivity analysis showed that the ICERs were most sensitive to health service utilization rates. While the factors influencing glycaemic control are multifactorial, six-monthly monitoring is potentially cost-effective while more frequent monitoring could further improve patient HrQoL., (© The Author(s) 2024. Published by Oxford University Press in association with The London School of Hygiene and Tropical Medicine.)
- Published
- 2024
- Full Text
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6. A National Laboratory Perspective: The Impact of the Covid-19 Pandemic on the Management of Patients With Non-Communicable Disease in South Africa: Impact of COVID-19 on patients with noncommunicable diseases - ERRATUM.
- Author
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Kruger EC, Van der Westhuizen DJ, Erasmus RT, Banderker RB, Jacob D, Moodley N, Ngxamngxa U, Kengne AP, and Zemlin AE
- Subjects
- Humans, South Africa epidemiology, Pandemics, SARS-CoV-2, COVID-19 epidemiology, Noncommunicable Diseases epidemiology, Noncommunicable Diseases therapy
- Published
- 2024
- Full Text
- View/download PDF
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