Research Articles (Statistics)
Permanent URI for this collectionhttp://hdl.handle.net/2263/1835
A collection containing some of the full text
peer-reviewed/
refereed articles published by researchers from
the
Department
of Statistics
Browse
Recent Submissions
Now showing 1 - 20 of 522
Item Improved runs-rules precedence charts for monitoring the process location parameter(Springer, 2025-04) Human, Schalk William; Malela-Majika, Jean-Claude; Kritzinger, Pierre; malela.mjc@up.ac.zaRuns-rules are typically incorporated into control charts to increase their sensitivity to detect small process shifts. However, a drawback of this approach is that the resulting charts are unable to detect large shifts quickly. In this paper, improved runs-rules are introduced to the nonparametric precedence chart to address this limitation by maintaining the sensitivity to small process shifts, while improving the ability to detect large shifts in the process. Performance comparisons between the proposed precedence charts and the precedence charts with standard runs-rules are made in terms of their respective run-length characteristics. The results reveal that the precedence charts with improved runs-rules are superior to the competing charts in detecting large shifts in the process, while maintaining the same sensitivity in the detection of small shifts. A real-life example from the engineering field is given to demonstrate the application and implementation of the new charts.Item A power-cardioid candidate for wind direction modelling motivated by two South African case studies(Springer, 2025-04) Van Wyk-de Ridder, Delene; Rad, Najmeh Nakhaei; Arashi, Mohammad; Ferreira, Johan; Bekker, Andriette, 1958-; johan.ferreira@up.ac.zaWind energy claims a positive image globally; therefore, accurate modelling of wind direction at generation sites accurately can enhance the potential of this green energy source. The uncertain nature of wind direction can be modelled through probability distributions; in this paper, we propose a flexible yet simple distribution, namely the Power-Cardioid distribution, as an alternative and implementable candidate to model wind direction. After discussing some characteristics, the performance of the Power-Cardioid distribution is evaluated via a simulation study and applied to datasets of two wind farms in South Africa. The numerical results demonstrate that this distribution is a promising and exciting new candidate compared to well-known models within circular statistics.Item Development and validation of a knowledge, attitudes and practices (KAP) questionnaire for healthcare professionals on environmental sustainability in healthcare in Southern Africa(F1000 Research Ltd, 2024-10) Lister, Helga Elke; Mostert, Karien; Botha, Tanita; Field, Emma; Knock, Danté; Mubi, Natasha; Odendaal, Stefani; Rohde, Megan; Maric, FilipBACKGROUND: The triple planetary crisis of climate change, environmental pollution, and biodiversity loss is increasingly driving poor health outcomes worldwide. Healthcare systems and services are often not environmentally sustainable and compound the problem, while healthcare professionals are also recognised as key leaders in advancing sustainable healthcare. To adopt this leadership position, healthcare professionals’ knowledge, attitudes, and practices regarding environmental sustainability in healthcare must be established. This article reports the development and validation of a new instrument for this purpose that corresponds to the specificities of the Southern African context. METHODS: Questionnaire development followed a seven-stage process. Information was obtained from a 2021 study titled ‘South African Healthcare Professionals’ Knowledge, Attitudes, and Practices Regarding Environmental Sustainability in Healthcare: A Mixed Methods Study’ to develop the instrument. Information was also sourced from the literature regarding environmental sustainability and healthcare to generate the first questionnaire with 29 items. The following stages included two rounds of expert input, separated by a pilot study with the target population to receive feedback regarding the instrument’s structure, relevance, and length. Content validity was determined through statistical analysis. RESULTS: Feedback was received from nine experts in stage two and 13 pilot study participants in stage four and incorporated to improve the questionnaire. In stage six, the questionnaire was rated by seven experts. The content validity index of the questionnaire was calculated at two different stages, after which the indices were compared. Following a final edit, the questionnaire has 24 questionnaire items. The closing analysis calculated the scale content validity index average (S-CVI/Ave) of 0,922; this indicates that the final questionnaire has excellent content validity. CONCLUSION: A questionnaire that assesses the knowledge, attitudes and practices of healthcare professionals regarding environmental sustainability in Southern Africa has been developed and validated. This questionnaire can now be used for further studies in Southern Africa.Item Robust PCA with Lw,∗ and L2,1 norms : a novel method for low-quality retinal image enhancement(MDPI, 2024-07) Likassa, Habte Tadesse; Chen, Ding-Geng (Din); Chen, Kewei; Wang, Yalin; Zhu, WenhuiPlease read abstract in the article.Item An optimised rabies vaccination schedule for rural settlements(Elsevier, 2025-03) Botes, Rian Hendrik; Fabris-Rotelli, Inger Nicolette; Mahloromela, Kabelo; Chen, Ding-Geng (Din); inger.fabris-rotelli@up.ac.zaPlease read abstract in the article.Item Mortality trends and causes of death in a South African hospital complex pre- and during COVID-19(AOSIS, 2025-03) Tshabalala, Khanyisile; Fabris-Rotelli, Inger Nicolette; Basu, Debashis; Myburgh, Magriet; Abdullah, Fareed; khanyisile.tshabalala@ up.ac.zaBACKGROUND : Before coronavirus disease 2019 (COVID-19), global health was improving, with declining mortality trends. The pandemic disrupted this progress, increasing mortality in South Africa between April 2020 and March 2022. Pre-pandemic data establishes a baseline for assessing COVID-19’s impact on all-cause mortality. OBJECTIVES : This study examines changes in hospital-based mortality trends in a Gauteng hospital complex from April 2018 to March 2022, addressing the scarcity of such studies during the COVID-19 era. METHOD : A retrospective review of 7815 deaths from April 2018 to March 2022 was conducted. Chi-squared tests were used to analyse deaths by age group and gender, with correlations reported. RESULTS : Mortality rates rose from 3.2% in 2018–2019, peaked at 5.1% in 2020–2021, and declined to 4.2% in 2021–2022. Patients aged 15 years–64 years had the highest death rates, with an increase among those over 65. Male deaths exceeded female deaths, with the smallest difference observed in 2020–2021. Leading causes of death included diseases of the circulatory and respiratory systems, neoplasms, digestive system diseases, and infectious and parasitic diseases. CONCLUSION : The study highlights COVID-19’s impact on mortality, showing variations by year, age, gender, and disease. Contribution: Excess non-COVID-19 deaths likely stemmed from disrupted healthcare services. These findings underscore the need for ongoing monitoring of hospital mortality to identify pandemic-related service disruptions and guide interventions to strengthen healthcare services, improve access to care, and enhance referral systems during unexpected disasters.Item Contest competition and injury in adult male sub-Antarctic fur seals(Springer, 2024-05) Bester, Marthan Nieuwoudt; Rossouw, G.J.; Van Staden, Paul Jacobus; mnbester@zoology.up.ac.zaWe recorded intra-sexual behaviour of adult male sub-Antarctic fur seals Arctocephalus tropicalis at Gough Island, Southern Ocean, during the 1975/76 summer breeding season. Our re-analysed data address male ‘contest competition’, which relates to the costs of intra-sexual disputes, including fights. We considered the risks/benefits of fighting through investigation of injuries (n = 353) sustained by adult males (n = 124) in fights. Injuries were predominantly on the forequarters, especially around the insertion areas of the front flippers (41%) with its sparse pelage, compared to the neck and chest areas combined (29%), an area which is well protected by thick pelage. The infliction of serious, sometimes debilitating, injuries to competitors increases a male’s access to females. Injuries predominate in injured, defeated males that gather at non-breeding sites, suggesting that injuries inflicted by dominant males were successful in excluding competing males from breeding sites.Item Partial proportional odds of child polio vaccination status among children aged 12–23 Months in Ethiopia(Wiley, 2025-04) Belay, Alebachew Taye; Belay, Denekew Bitew; Yilema, Seyifemickael Amare; Moyehodie, Yikeber AbebawBACKGROUND : The poliovirus is mostly transmitted by the fecal–oral route and can cause viremia after replication in the gastrointestinal tract. The current global coverage of polio immunization is 85%, against the 90% target, while the total coverage of inactivated polio vaccine (IPV) coverage in sub-Saharan Africa is 73%. Only 30% of the children living in rural areas of Ethiopia were fully vaccinated at the appropriate ages in 2016 EDHS (Ethiopian Demographic and Health Survey) data. This study evaluated the prevalence and factors associated with the vaccination status of children aged 12 and 23 months in Ethiopia. METHODS : The Ethiopian Mini Demographic and Health Survey 2019 (Mini EDHS, 2019) was used for this study. The partial proportional ordinal logistic regression model was used to determine the risk factors associated with the polio vaccination status of children aged 12 and 23 months using SAS version 9.40 statistical software at a 5% level of significance. RESULTS : The prevalence of polio vaccination status of children showed that about 33.00% of children never received vaccination, 21.20% were partially vaccinated, and 45.70% were fully vaccinated. The age of mother (AOR [adjusted odds ratio] = 1.06, 95% CI: 1.025, 1.094), age of mother at the first birth (AOR = 0.94, 95% CI: 0.909, 0.976), rural residence (AOR = 0.66; 95% CI: 0.499, 0.867), higher education (AOR = 1.25; 95% CI: 1.241, 1.730), at least four and more ANC (AOR = 2.34; 95% CI: 1.845, 2.968), and ANC visits in health facilities (AOR = 2.33, 95% CI: 1.902, 2.864) had a significant effect on child polio vaccination. CONCLUSION : The coverage of full polio vaccination in Ethiopia was below 50%, which is below the global and regional percentage. Policies and programs must be formulated and implemented with a strong focus on women who have not used ANC visits, residents in rural areas, and uneducated women in child vaccination must be considered in Ethiopia.Item The impact of past and current district-level climatic shifts on maize production and the implications for South African farmers(Springer, 2025-02) Mangani, Robert; Mazarura, Jocelyn; Matlou, Solly; Marquart, Arnim; Archer, Emma Rosa Mary; Creux, Nicky; nicole.creux@fabi.up.ac.zaSouth Africa’s climate studies generally focus on coarser provincial levels, which aid policy recommendations, but have limited application at the farm level. District level climate studies are essential for farmer participation in climate change mitigation strategies and management. Our study aimed to investigate historical climate data for trends and their influence on maize yields at the magisterial level. Six sites were selected from three major maize-producing provinces in South Africa: Mpumalanga, Northwest, and Free State. Magisterial districts in each province were selected from different Köppen-Geiger climate zones. The climate variables assessed by the Mann–Kendall trend test included maximum or minimum temperature, rainfall, number of extreme high-temperature days, rainfall onset and cessation from 1986 to 2016. The average maximum temperatures were observed to have significant upward trends in most locations, except for Schweizer-Reneke and Bethlehem. The fastest rate of change was observed at Klerksdorp (0.1 °C per 30 years of study), while the Schweizer-Reneke district was the slowest (0.05 °C per 30 years of study). No significant changes were observed in rainfall onset, cessation, or total rainfall in Schweizer-Reneke, Standerton, and Bethlehem, which are scattered across the different provinces. The other districts in each province showed significant changes in these parameters. Rainfall accounted for the significant variation in maize yields over the study period, explaining between 18 and 40% of the variation in the North West, and between 1 and 17% in the Free State. These findings highlight the importance of understanding location-specific changes at a finer scale, which can help farming communities adjust agronomic practices and adapt to local climate shifts.Item Gynaecological health patterns and motherhood experiences of female professional football players(MDPI, 2025-02) Ramagole, Dimakatso Althea; Janse van Rensburg, Dina Christina; Cowie, Charlotte; Mehta, Ritan; Ramkilawon, Gopika Devi; Pluim, Babette M.; Kerkhoffs, Gino M.M.J.; Gouttebarge, VincentThe aim of this paper is to explore the gynaecological health patterns, contraceptive use, body perception, and motherhood experiences of female professional football players. The participants were recruited via email using FIFPRO (Football Players Worldwide). Online questionnaires were completed by consenting participants. The mean age at menarche was 13.5 years with an average cycle length of 26 days, and a bleeding period of 5 days. Cycle irregularities were experienced by 30%, and menstrual symptoms by 74%. Half of the participants used contraceptives, 60% using hormonal contraceptives, primarily oral contraceptive pills (38%), followed by implants (20%). The body satisfaction score was normal but there was a high drive-for-thinness (DT) score. The motherhood rate was low (1%), with participants experiencing normal conception, vaginal delivery, return to training after 6 weeks, and return to competition after 12 weeks. Our findings are consistent with findings in other elite female athletes with cycle irregularities and a significant number of cycle-related symptoms. The majority of those using contraceptives preferred hormonal contraceptives, reflecting trends seen in other elite athletes. While body satisfaction scores were normal, there was a high DT score, similar to that observed in lean and weight-category sports. The motherhood rate was low, consistent with previous findings in professional football players and other elite athletes. This may be due to a lack of financial support during pregnancy and the post-partum period. FIFPRO and its affiliated unions are negotiating better contracts for female football players.Item Identification of common spatial and temporal trends in the epidemiology of cattle bovine tuberculosis and human extrapulmonary and drug-resistant tuberculosis in Malawi(Elsevier, 2024-12) Ngwira, Alfred; Manda, S.O.M. (Samuel); Karimuribo, Esron D.; Kimera, Sharadhuli IddiBACKGROUND: Identification of common spatial disease trends between cattle bovine tuberculosis (BTB) and human extrapulmonary tuberculosis (EPTB) and drug-resistant tuberculosis (DRTB) can support integrated disease control and monitoring programmes. We employed the recently developed multivariate disease mapping methods to examine whether the diseases exhibited any spatial correlation. METHODS: A retrospective study of cattle BTB and human EPTB and DRTB cases from 2018 to 2022 was conducted. Bivariate shared spatiotemporal components models were fitted to a) cattle BTB and human EPTB and b) cattle BTB and human DRTB at the district level in Malawi, with cattle density, human density and climatic variables as independent variables. RESULTS: Disease specific spatial effects were higher in the southern half of the country, while the shared spatial effects were more dominant in both the south and western parts of the country. The shared temporal effects showed constant trends, while disease specific temporal effects showed an increasing pattern for cattle BTB and a constant pattern for human EPTB and DRTB. The predicted disease incidence pattern for all forms of TB in the period without data showed a constant pattern over the years. Cattle density was positively associated with cattle BTB (: 0.022; 95% Credible Interval (CI): 0.004, 0.042). Human density was positively associated with human EPTB (: 0.005; 95% CI: 0.001, 0.009). CONCLUSION: Cattle BTB and human EPTB and DRTB have a common spatial pattern in the west and southern parts of Malawi. Integrated interventions targeting high-density areas for cattle and human may have positive impacts on cattle BTB and human EPTB and DRTB.Item Alternative skew Laplace scale mixtures for modeling data exhibiting high-peaked and heavy-tailed traits(Springer, 2024-11) Otto, A.F.; Bekker, Andriette, 1958-; Ferreira, Johannes Theodorus; Arslan, O.; johan.ferreira@up.ac.zaThe search and construction of appropriate and flexible models for describing and modelling empirical data sets incongruent with normality retains a sustained interest. This paper focuses on proposing flexible skew Laplace scale mixture distributions to model these types of data sets. Each member of the collection of distributions is obtained by dividing the scale parameter of a conditional skew Laplace distribution by a purposefully chosen mixing random variable. Highly-peaked, heavy-tailed skew models with relevance and impact in different fields are obtained and investigated, and elegant sampling schemes to simulate from this collection of developed models are proposed. Finite mixtures consisting of the members of the skew Laplace scale mixture models are illustrated, further extending the flexibility of the distributions by being able to account for multimodality. The maximum likelihood estimates of the parameters for all the members of the developed models are described via a developed EM algorithm. Real-data examples highlight select models’ performance and emphasize their viability compared to other commonly considered candidates, and various goodness-of-fit measures are used to endorse the performance of the proposed models as reasonable and viable candidates for the practitioner. Finally, an outline is discussed for future work in the multivariate realm for these models.Item Hospital accessibility catchment areas as a fuzzy lattice data structure(Copernicus Publications, 2024-10) De Klerk, Michelle; Fabris-Rotelli, Inger Nicolette; inger.fabris-rotelli@up.ac.zaThe accessibility to basic facilities and services plays a pivotal role in every society and city planning. Spatial accessibility can vary between cities and countries and is mainly defined by the ease at which facilities can be accessed by communities. Facilities can provide essential services and/or products such as pharmacies, clinics, schools, universities, etc. Spatial accessibility is dependent on the spatial impedance between a facility and the target population and can be illustrated with catchment areas. We propose a fuzzy lattice catchment area method which uses a semi-supervised learning algorithm to create overlapping catchment areas. This methodology is applied to determine the accessibility to hospitals in South Africa and provides an illustration on the difference for regions with high accessibility compared to low accessibility. The application can easily be adapted in a variety of fields based on industry type, drive-time thresholds, supply capacity and the target population.Item Exploring the effect of road network structure on inter-regional accessibility in a diverse road network(Copernicus Publications, 2024-10) Thiede, Renate Nicole; Fabris-Rotelli, Inger Nicolette; Debba, Pravesh; Cleghorn, Christopher; inger.fabris-rotelli@up.ac.zaAccessibility analyses quantify the level of access to certain areas or opportunities, such as employment and healthcare facilities. Since public data is often aggregated at the level of regions, such as administrative units, it is useful to quantify accessibility between regions. Many factors influence inter-regional accessibility, most notably the accessibility metric used, and the way in which regions are chosen. This paper investigates the effects of road network structure on accessibility, using a previously developed inter-regional accessibility model that bases its accessibility metric on travel distance via the road network. This paper considers an area within the City of Tshwane municipality in South Africa. We investigate the effects of road structure in two ways. Firstly, regions are chosen based on the road network structure, which is done by extending a previously developed road network clustering algorithm for this novel use. Different spatial scales of regionalisation are considered, and the accessibility between these regions is compared to the accessibility between administrative units within the study area. Secondly, the effect of road network homogeneity on accessibility is investigated, where homogeneity corresponds to a uniform concentration of roads across a region. The results show that although road network homogeneity does not significantly correlate with accessibility, the way in which regions are chosen and their spatial scale has a strong effect on the results of the accessibility model. Our novel method of obtaining regions thus provides fresh insights into road-based accessibility within the City of Tshwane.Item Assessing classification performance for sampled remote sensing data(Copernicus Publications, 2024-10) Rangongo, Tshepiso Selaelo; Fabris-Rotelli, Inger Nicolette; Thiede, Renate Nicole; renate.thiede@up.ac.zaBig data poses challenges for storage, management, processing, analysis and visualisation. One technique of handling big data is the use of a representative sample of the data. This paper proposes a sampling algorithm which makes use of multivariate stratification with the aim of obtaining a sample that best represents the population while minimising the number of images in the sample. The proposed sampling algorithm performs effectively on a big spatial image dataset of crop types. The results are assessed by measuring the number of images sampled and as well as matching the proportionality of the population crop percentages. The samples obtained from the proposed algorithm are then used for land cover classification. An ensemble method called random forest is trained on the samples and accuracy is assessed. Precision, recall and F1-scores per crop type are computed as well as the overall accuracy. The random forest classifier performed best on the proposed sample with the least number of images. In addition, the classifier performed better on the proposed sample than it did on a random sample as the proposed sample due to the more informative data. This research develops an effective way of sampling big data for crop classification.Item A novel RPCA method using log-weighted nuclear and L2,1 norms combined with contrast-limited adaptive histogram equalization (CLAHE) for high dimensional natural and medical image data(Lifescience Global, 2024-11-26) Likassa, Habte Tadesse; Chen, Ding-Geng (Din); Sun, DayuPlease read abstract in the article.Item Illness is more prevalent than injury in trail runners participating in a mountainous ultra trail race(Taylor and Francis, 2025) Boshielo, Patience Matshepo; Jansen van Rensburg, Audrey; Viljoen, Carel Thomas; Botha, Tanita; De Villiers, Christina Elizabeth; Ramagole, Dimakatso Althea; Seyani, Limbikani; Janse van Rensburg, Dina ChristinaOBJECTIVES : Trail running is a popular off-road sport involving running in natural environments over various terrains, often in remote locations. This study aims to investigate the epidemiology and risk factors of injuries and illnesses, i.e. medical encounters, on race day among trail runners in a high-altitude ultra trail race. METHODS : This descriptive cross-sectional study on an ultra trail race (38 km, 65 km and 100 km) in South Africa, included participants 18 years or older. Of the 331 race participants, 285(86.1%) consented to participate in the study. Data collection included demographic details, injuries (body region, specific body area, tissue type, pathology) and illnesses (organ system, symptom cluster, etiology). Risk factor analysis includes sex, age, weight, height, race distance, illness and injury history, training and running experience. Frequency (n, %), prevalence (%) and odds ratios (OR; 95%CI) are reported. RESULTS : Eighty-nine (31.2%) individuals reported 131 medical encounters [49 injuries (37.4%); 82 illnesses (62.6%)]. Injuries were sustained by 14.7% of athletes, and 22.5% reported illnesses. For injuries, the lower limb was mainly involved (n = 41; 83.7%). Most injuries affected the foot (n = 18; 36.7%), ankle (n = 10; 20.4%) and knee (n = 7; 14.3%). Tissue types mainly involved skin (n = 21; 42.8%), ligament (n = 7; 14.3%) and muscle (n = 7; 14.3%). Multiple (n = 45; 54.9%) and gastrointestinal (n = 17; 20.7%) organ systems were mainly involved in illnesses. Only 100 km runners reported dehydration (n = 28; 31.5%), and one in every six of these runners (n = 5; 17.9%) did not finish. Runners reporting fatigue (n = 21; 23.6%) had a high (n = 8; 38.1%) did not finish rate. Two in every five participants (n = 36; 40.4%) with a medical encounter, did not finish. No medical encounter-associated risk factors were identified. CONCLUSIONS : Illnesses were more common than injuries during the mountainous ultra trail race. Sustaining a medical encounter increased the chance of not completing the race. Further research on the epidemiology of race day medical encounters in trail running is required.Item Investigation of neopterin and neurophysiological measurements as biomarkers of anxiety and stress(International Society for Neurofeedback & Research, 2024-03-29) Cronje, Rouxzan; Beukes, Johanni; Masenge, Andries; Du Toit, P.J.; Bipath, Priyesh; u17027617@tuks.co.zaThe aim of this study was to investigate whether the inflammatory marker neopterin and certain neurophysiological measurements could be used as complementary markers for stress and anxiety symptoms as determined by the Depression, Anxiety, and Stress Scale (DASS-21) questionnaire. A cohort of 158 respondents completed the DASS-21 and biographical questionnaire which were used to stratify health sciences university students between Group A (n = 20), who had high levels of symptoms, and Group B (n = 20) who had normal levels of stress and anxiety. Neurophysiological measurements were taken from these participants, namely heart rate variability (HRV), blood pressure (BP), blood-volume pulse (BVP), electrodermal activity (EDA), and quantitative electroencephalography (qEEG). Each participant also donated a urine sample which was tested for neopterin concentration using an enzyme-linked immunosorbent assay (ELISA). Neopterin positively correlated with the stress and anxiety scores, while HRV and BVP were negatively correlated with these scores. In terms of qEEG, delta and hibeta wave activity increased in the left and frontal brain regions of participants with high mental health scores, whereas alpha wave activity decreased in these regions. High DASS scores were associated with elevated neopterin concentration and neurophysiological changes (brain waves, HRV, and BVP).Item T-cell phenotypes and systemic cytokine profiles of people living with HIV admitted to hospital with COVID-19(MDPI, 2024-11) Van der Mescht, Mieke Adri; Steel, Helen C.; De Beer, Zelda; Masenge, Andries; Abdullah, Fareed; Ueckermann, Veronica; Anderson, Ronald; Rossouw, Theresa M.; theresa.rossouw@up.ac.zaWhether SARS-CoV-2 infection leads to a higher mortality and morbidity in people living with HIV (PLWH) in Africa remains inconclusive. In this study, we explored the differences in the T-cell phenotypes between people with and without HIV on the day of admission (V1) and ±7 days later (V2), as well as their cytokine/chemokine profiles on V1. Patients admitted with COVID-19 were recruited between May 2020 and December 2021 from the Steve Biko Academic and Tshwane District Hospitals in Pretoria, South Africa. Of 174 patients, 37 (21%) were PLWH. T-cell profiles were determined by flow cytometry, and cytokine levels were determined using a multiplex suspension bead array. PLWH were significantly younger than those without HIV, and were more likely to be female. In an adjusted analysis, PLWH had higher percentages of CD4+ central memory (CM) programmed cell death protein 1 (PD-1)+, CD8+ effector memory (EM)2, and CD8+ EM4 CD57+ cells, as well as higher concentrations of interleukin (IL)-35 at admission. PLWH with CD4+ T-cell counts of >200 cells/mm3 had altered CD4+ and CD8+ T-cell profiles, lower levels of systemic inflammation measured by plasma ferritin and PCT levels, and less severe disease. PLWH with CD4+ T-cell counts of <200 cells/mm3 on admission had higher concentrations of IL-6 and lower levels of IL-29. At V2, the percentages of CD4+ CM PD-1+ T-cells and CD8+ EM4 T-cells co-expressing CD57 and PD-1 remained higher in PLWH, while all other CD8+ EM populations were lower. Fewer CD8+ EM T-cells after ±7 days of admission may be indicative of mechanisms inhibiting EM T-cell survival, as indicated by the higher expression of IL-35 and the T-cell maturation arrest observed in PLWH. This profile was not observed in PLWH with severe immunodeficiency, highlighting the need for differentiated care in the broader PLWH population.Item A study of the incidence of the corona mortis within a South African patient sample using computerized tomographic angiography(Elsevier, 2024-12) Naicker, Jade; Tshabalala, Zithulele Nkosinathi; Janse van Rensburg, Jacques; Masenge, Andries; Modisane, Obakeng; Matshidza, Steven; Mogale, Nkhensani; Naicker.Jade@up.ac.zaINTRODUCTION: Retropubic hematomas are a common development in cases of pelvic ring trauma and post-operative repair of fractures to the anterior column of the pelvis. Early detection and diagnosis of such events using computed tomography angiography (CTA) are critical for successful intervention and patient recovery, especially when bleeding is a result of injury to the corona mortis (CM). The CM is the communication between the obturator vessels and the external iliac vessels typically via an accessory obturator vessel. This communication of vessels is identified as a major hindrance in anterior approaches to the pelvis. MATERIALS AND METHODS: This study investigated the incidence of CM and mapped out safe zones for the anastomosis in a South African sample using 73 adult angiograms from the Department of Diagnostic Radiology, Universitas Academic Hospital. After careful observation of the iliac system, the incidence of CM was documented. The distance from the CM to clinically relevant bony landmarks were recorded to formulate safe zones. RESULTS: The incidence of CM was observed in 33.1 % of the sample, with 20 % being venous and 13.1 % being arterial anastomoses. Statistically significant differences between the sexes were noted for safe zones between all landmarks except for the pubic tubercle (p ≥ 0.26). The safe zone between the CM and the pubic tubercle were documented as 46.88 mm and the average diameter for all anastomotic vessels was noted as 2.83 mm (Range: 1.75 - 4.61 mm). CONCLUSION: The inconsistencies presented in angiogram studies compared to cadaver studies suggest that angiograms should be limited to a diagnostic and therapeutic role of identifying the CM or injury thereof in the retropubic region. However, measurements concerning safe zones should rather be extracted from cadaveric studies.