Browsing by Author "Davids, M. R."
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- ItemCalcific uraemic arteriolopathy (calciphylaxis) in patients on renal replacement therapy(Health and Medical Publishing Group, 2017) Sebastian, S.; Jordaan, H. F.; Schneider, J. W.; Moosa, M. R.; Davids, M. R.Background. Calcific uraemic arteriolopathy (calciphylaxis) is an unusual and potentially fatal condition characterised by small-vessel calcification and ischaemic skin necrosis. It mainly affects patients with end-stage renal disease (ESRD) on haemodialysis, but may rarely occur in the absence of ESRD in conditions such as primary hyperparathyroidism, malignancy, alcoholic liver disease and connective tissue disease. Methods. We reviewed the records of all patients diagnosed with calciphylaxis while on renal replacement therapy at Tygerberg Hospital, Cape Town, South Africa, between 1990 and 2014, to describe its presentation, course and final outcome. Results. Nineteen patients developed calciphylaxis over this period. Their median age was 34 years and 13 (68.4%) were female. Fifteen (78.9%) had received a kidney transplant. All patients had painful skin lesions that rapidly progressed to infarction. Small-vessel calcification was seen on skin biopsy in 13 patients. Twelve patients had hyperparathyroidism. Several of the transplanted patients had been treated for graft rejection in the year preceding the diagnosis. Treatment consisted of good wound care and efforts to normalise serum calcium and phosphate levels. Five patients received an urgent parathyroidectomy. The outcome was fatal in 17 patients, with sepsis being the main cause of death. Conclusions. In our patients, calciphylaxis carried a worse prognosis than previously reported internationally. It should always be considered in the differential diagnosis of painful skin lesions in the dialysis or transplant patient.
- ItemChronic kidney disease for the primary care clinician(South African Academy of Family Physicians, 2019-10-28) Davids, M. R.; Chothia, M. Y.ENGLISH ABSTRACT: An epidemic of chronic kidney disease (CKD) is being experienced in South Africa. This is driven by a heavy burden of infections, non-communicable diseases, pregnancy-related diseases and injuries. The serious long-term complications of CKD include end-stage renal disease, heart disease and stroke. Competing priorities such as the high burden of HIV, tuberculosis and other infections, unemployment and poverty result in serious constraints to providing comprehensive renal care, especially in the public healthcare sector. The prevention and early detection of CKD by primary care practitioners is therefore of utmost importance. Annual screening is recommended for patients at high risk of developing CKD. This involves checking blood pressure, urine dipstick testing for albuminuria or proteinuria and estimating the glomerular filtration rate from serum creatinine concentrations. In patients with established CKD, renoprotective measures are indicated to arrest or slow down the loss of renal function. These patients are at high risk of cardiovascular disease and close attention should be paid to optimally managing their risk factors.
- ItemHybrid imaging using low-dose, localizing computed tomography enhances lesion localization in renal hyperparathyroidism(Lippincott, Williams & Wilkins, 2014-03) Doruyter, Alexander G.; Hartley, Tharbit; Ameyo, Jonathan W.; Davids, M. R.; Warwick, James M.Background Preoperative localization of parathyroid lesions is potentially beneficial in renal patients with hyperparathyroidism. The aim of this study was to determine the localizing value of hybrid single-photon emission computed tomography combined with low-dose x-ray computed tomography (SPECT/LDCT) compared with SPECT alone and whether the LDCT improved reader confidence. Patients and methods A retrospective study examined parathyroid scintigraphy results of patients previously referred with a diagnosis of renal hyperparathyroidism. All patients underwent planar scintigraphy using technetium- 99m (99mTc)-pertechnetate, which was immediately followed with 99mTc-sestamibi and SPECT/LDCT ∼ 60 min after sestamibi injection and a delayed static image to assess differential washout. Planar subtraction images were generated. Two nuclear physicians, assisted by a radiologist, reported on planar+SPECT images followed by planar+SPECT/LDCT images. Results Thirty-seven patients (males: 21; females: 16) were included (mean age 39 years, range: 23.9–55.5). Mean creatinine level was 878 μmol/l (109–1839), mean corrected calcium level was 2.42 mmol/l (1.77–3.64), and median parathyroid hormone level was 156.2 pmol/l (2.4 to >201). Twenty-three patients had positive planar and SPECT
- ItemMycophenolate mofetil versus cyclophosphamide for induction treatment of lupus nephritis(2009) Appel, G. B.; Contreras, G.; Dooley, M. A.; Ginzler, E. M.; Isenberg, D.; Jayne, D.; Li, L-S.; Mysler, E.; Sanchez-Guerrero, J.; Solomons, N.; Wofsy, D.; Abud, C.; Adler, S.; Alarcon, G.; Albuquerque, E.; Almeida, F.; Alvarellos, A.; Appel, G.; Avila, H.; Blume, C.; Boletis, I.; Bonnardeaux, A.; Braun, A.; Buyon, J.; Cervera, R.; Chen, N.; Chen, S.; Da Costa, A. G.; Davids, M. R.; D'Cruz, D.; De Ramon, E.; Deodhar, A.; Doria, A.; Dussol, B.; Emery, P.; Fiechtner, J.; Floege, J.; Fragoso-Loyo, H.; Furie, R.; Ghazalli, R.; Ghossein, C.; Gilkeson, G.; Ginzler, E.; Gordon, C.; Grossman, J.; Gu, J.; Guillevin, L.; Hatron, P. Y.; Herrera, G.; Hiepe, F.; Houssiau, F.; Hubscher, O.; Hura, C.; Kaplan, J.; Kirsztajn, G.; Kiss, E.; Kutty, G. A.; Laville, M.; Lazaro, M.; Lenz, O.; Li, L.; Lightstone, L.; Lim, S.; Malaise, M.; Manzi, S.; Marcos, J.; Meyer, O.; Monge, P.; Naicker, S.; Neal, N.; Neuwelt, M.; Nicholls, K.; Olsen, N.; Ordi-Ros, J.; Ostrov, B.; Pestana, M.; Petri, M.; Pokorny, G.; Pourrat, J.; Qian, J.; Radhakrishnan, J.; Rovin, B.; Roman, J. S.; Shanahan, J.; Shergy, W.; Skopouli, F.; Spindler, A.; Striebich, C.; Sundel, R.; Swanepoel, C.; Si, Y. T.; Tate, G.; Tesar, V.; Tikly, M.; Wang, H.; Yahya, R.; Yu, X.; Zhang, F.; Zoruba, D.Recent studies have suggested that mycophenolate mofetil (MMF) may offer advantages over intravenous cyclophosphamide (IVC) for the treatment of lupus nephritis, but these therapies have not been compared in an international randomized, controlled trial. Here, we report the comparison of MMF and IVC as induction treatment for active lupus nephritis in a multinational, two-phase (induction and maintenance) study. We randomly assigned 370 patients with classes III through V lupus nephritis to open-label MMF (target dosage 3 g/d) or IVC (0.5 to 1.0 g/m2 in monthly pulses) in a 24-wk induction study. Both groups received prednisone, tapered from a maximum starting dosage of 60 mg/d. The primary end point was a prespecified decrease in urine protein/creatinine ratio and stabilization or improvement in serum creatinine. Secondary end points included complete renal remission, systemic disease activity and damage, and safety. Overall, we did not detect a significantly different response rate between the two groups: 104 (56.2%) of 185 patients responded to MMF compared with 98 (53.0%) of 185 to IVC. Secondary end points were also similar between treatment groups. There were nine deaths in the MMF group and five in the IVC group. We did not detect significant differences between the MMF and IVC groups with regard to rates of adverse events, serious adverse events, or infections. Although most patients in both treatment groups experienced clinical improvement, the study did not meet its primary objective of showing that MMF was superior to IVC as induction treatment for lupus nephritis. Copyright © 2009 by the American Society of Nephrology.
- ItemOptimising cognitive load and usability to improve the impact of e-learning in medical education(Health & Medical Publishing Group, 2015) Davids, M. R.; Halperin, M. L.; Chikte, U. M. E.E-learning has the potential to support the development of expertise in clinical reasoning by being able to provide students with interactive learning experiences, exposure to multiple cases, and opportunities for deliberate practice with tailored feedback. This review focuses on two important but underappreciated factors necessary for successful e-learning, i.e. the management of the learner’s cognitive load and the usability of the technology interface. Cognitive load theory views learning as involving active processing of information by working memory via separate visual and auditory channels. This system is of very limited capacity and any cognitive load that does not directly contribute to learning is considered extraneous and likely to impede learning. Researchers in cognitive load theory have provided evidence-based instructional design principles to reduce extraneous cognitive load and better manage the cognitive processing necessary for learning. Usability is a concept from the field of human-computer interaction which describes how easy technology interfaces are to use, and is routinely evaluated and optimised in the software development industry. This is seldom the case when e-learning resources are developed, especially in the area of medical education. Poor usability limits the potential benefit of educational resources, as learners experience difficulties with the technology interface while simultaneously dealing with the challenges of the content presented. Practitioners in the field of human-computer interaction have provided guidelines and methods for evaluating and optimising the usability of e-learning materials. The fields of cognitive load theory and human-computer interaction share a common goal in striving to reduce extraneous cognitive load. The load induced by poor usability of e-learning materials can be viewed as a specific component of extraneous cognitive load, adding to any load resulting from poor instructional design. The guidelines from these two fields are complementary and, if correctly implemented, may substantially improve the impact of our e-learning resources on the development of the clinical reasoning skills of students.
- ItemSouth African renal registry annual report 2012(South African Renal Society, 2012-04) Davids, M. R.; Marais, N.; Jacobs, J. C .INTRODUCTION: This first report of the new South African Renal Registry provides data on renal replacement therapy (RRT) for patients with end-stage renal disease (ESRD) in South Africa. Our previous registry, the South African Dialysis and Transplantation Registry, last reported data from 1994 and we have had a lack of reliable data on RRT in South Africa for the past two decades. The simple numbers we present here tell a story of many striking changes since 1994. The population of the country has increased by around 12 million people, with certain provinces showing massive increases compared to others. The prevalence of patients on RRT in South Africa is 164 per million population (pmp). There is an uneven distribution of RRT across provinces and large differences in treatment rates between the public and private sectors. Overall, the provision of RRT has increased, but remains below the rates seen in other countries with similar or lesser incomes per capita. The growth in RRT is mainly due to an increase in patients on haemodialysis in the private sector; the provision of RRT in the public sector has not increased substantially since 1994. The numbers of patients with functioning kidney transplants are similar to those reported in 1994. Transplanted patients now constitute less than 20% of the patients on RRT, as compared to more than 50% in 1994.
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- ItemUsability testing of a multimedia e-learning resource for electrolyte and acid-base disorders(Wiley Online Open, 2013-04) Davids, M. R.; Chikte, Usuf M. E.; Grimmer-Somers, Karen; Halperin, Mitchell L.The usability of computer interfaces may have a major influence on learning. Design approaches that optimize usability are commonplace in the software development industry but are seldom used in the development of e-learning resources, especially in medical education. We conducted a usability evaluation of a multimedia resource for teaching electrolyte and acid-base disorders by studying the interaction of 15 medical doctors with the application. Most of the usability problems occurred in an interactive treatment simulation, which was completed successfully by only 20% of participants. A total of 27 distinct usability problems were detected, with 15 categorized as serious. No differences were observed with respect to usability problems detected by junior doctors as compared with more experienced colleagues. Problems were related to user information and feedback, the visual layout, match with the real world, error prevention and management, and consistency and standards. The resource was therefore unusable for many participants; this is in contrast to good scores previously reported for subjective user satisfaction. The findings suggest that the development of e-learning materials should follow an iterative design-and-test process that includes routine usability evaluation. User testing should include the study of objective measures and not rely only on self-reported measures of satisfaction.
- ItemValidation of equations to estimate glomerular filtration rate in South Africans of mixed ancestry(Health & Medical Publishing Group, 2020-02-26) Holness, Jen L.; Bezuidenhout, K.; Davids, M. R.; Warwick, J. M.Background. The Modification of Diet in Renal Disease (MDRD) and Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equations are two commonly used formulae to estimate glomerular filtration rate (GFR) in adults. The CKD-EPI equation is recommended in current international and local guidelines for the diagnosis and management of chronic kidney disease (CKD), unless an alternative equation has been shown to have superior accuracy. Validation and comparison of the equations in local populations are therefore required. Previous studies have reported on the accuracy of these prediction equations in black South Africans and those of Indian ancestry. Objectives. To evaluate the MDRD and CKD-EPI equations in South African (SA) adults of mixed ancestry. Methods. In all participants, GFR was measured (mGFR) from plasma clearance of 99mTc-diethylenetetraaminepenta-acetic acid (99mTc-DTPA), using a standardised technique. Serum creatinine assays were isotope dilution mass spectrometry traceable. GFR was estimated (eGFR) using the MDRD and CKD-EPI equations, with and without the black ethnicity factor. The agreement, bias, precision and accuracy of each equation was determined. Results. Eighty adults were included (30 male, median age 39 years, median GFR 59 mL/min/1.73 m2). Sixty-eight had a diagnosis of CKD, 10 were potential kidney donors, and 2 were healthy volunteers. Both equations, without the black ethnicity factor, had good agreement with measured GFR. The equations tended to overestimate GFR, with bias of 1.6 and 7.9 mL/min/1.73 m2 for the MDRD and CKD-EPI equations, respectively. The interquartile ranges of the differences were 15.9 and 20.2 mL/min/1.73 m2, and as a measure of accuracy, the percentages of estimates that fell within 30% of the mGFR (P30) were 80% and 72.5% (p=0.18). For identification of individuals with a GFR <60 mL/min/1.73 m2, the sensitivity of MDRD eGFR was 97.3% and that of CKD-EPI eGFR was 97.1%. Conclusions. The MDRD and CKD-EPI equations have shown satisfactory and comparable performance in this SA mixed-ancestry adult population, with the MDRD equation marginally less biased than the CKD-EPI.