Browsing by Author "Zühlke, Liesl J"

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    Open Access
    Data-independent acquisition mass spectrometry in severe rheumatic heart disease (RHD) identifies a proteomic signature showing ongoing inflammation and effectively classifying RHD cases
    (2022-03-22) Salie, M T; Yang, Jing; Ramírez Medina, Carlos R; Zühlke, Liesl J; Chishala, Chishala; Ntsekhe, Mpiko; Gitura, Bernard; Ogendo, Stephen; Okello, Emmy; Lwabi, Peter; Musuku, John; Mtaja, Agnes; Hugo-Hamman, Christopher; El-Sayed, Ahmed; Damasceno, Albertino; Mocumbi, Ana; Bode-Thomas, Fidelia; Yilgwan, Christopher; Amusa, Ganiyu A; Nkereuwem, Esin; Shaboodien, Gasnat; Da Silva, Rachael; Lee, Dave C H; Frain, Simon; Geifman, Nophar; Whetton, Anthony D; Keavney, Bernard; Engel, Mark E
    Background Rheumatic heart disease (RHD) remains a major source of morbidity and mortality in developing countries. A deeper insight into the pathogenetic mechanisms underlying RHD could provide opportunities for drug repurposing, guide recommendations for secondary penicillin prophylaxis, and/or inform development of near-patient diagnostics. Methods We performed quantitative proteomics using Sequential Windowed Acquisition of All Theoretical Fragment Ion Mass Spectrometry (SWATH-MS) to screen protein expression in 215 African patients with severe RHD, and 230 controls. We applied a machine learning (ML) approach to feature selection among the 366 proteins quantifiable in at least 40% of samples, using the Boruta wrapper algorithm. The case–control differences and contribution to Area Under the Receiver Operating Curve (AUC) for each of the 56 proteins identified by the Boruta algorithm were calculated by Logistic Regression adjusted for age, sex and BMI. Biological pathways and functions enriched for proteins were identified using ClueGo pathway analyses. Results Adiponectin, complement component C7 and fibulin-1, a component of heart valve matrix, were significantly higher in cases when compared with controls. Ficolin-3, a protein with calcium-independent lectin activity that activates the complement pathway, was lower in cases than controls. The top six biomarkers from the Boruta analyses conferred an AUC of 0.90 indicating excellent discriminatory capacity between RHD cases and controls. Conclusions These results support the presence of an ongoing inflammatory response in RHD, at a time when severe valve disease has developed, and distant from previous episodes of acute rheumatic fever. This biomarker signature could have potential utility in recognizing different degrees of ongoing inflammation in RHD patients, which may, in turn, be related to prognostic severity.
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    Epidemiology of pharyngitis as reported by Zambian school children and their families: implications for demand-side interventions to prevent rheumatic heart disease
    (BioMed Central, 2017-07-06) Musuku, John; Lungu, Joyce C; Machila, Elizabeth; Jones, Catherine; Colin, Laurence; Schwaninger, Sherri; Musonda, Patrick; Tadmor, Brigitta; Spector, Jonathan M; Engel, Mark E; Zühlke, Liesl J
    Background: Prompt and appropriate treatment of streptococcal pharyngitis decreases the risk of acute rheumatic fever and rheumatic heart disease (RHD). Understanding public perceptions and behaviors related to sore throat is fundamental to inform health programs aimed at eliminating new cases of RHD in endemic regions. We sought to describe the epidemiology of pediatric pharyngitis and its treatment, as reported by children and their parents or guardians in Lusaka, Zambia. Methods: This was a cross-sectional investigation using interviews and written surveys, nested in a school-based RHD prevalence study. Students and their parents were asked to report number of sore throats in the previous 12 months, treatment received, and type and place of treatment. A focused history and physical examination to detect pharyngitis was conducted and children were referred for follow-up as indicated. Results: A total of 3462 students from 47 schools participated in the study, along with their parents or guardians. Six hundred and fifty eight (19%) parents/guardians reported their child had at least one sore throat in the previous year, and 835 (24%) of students reported at least one sore throat in the same time period. Girls were reported to have pharyngitis 50% more often than boys, and also made up two-thirds of the total students treated. Approximately two-thirds of children who had at least one episode of pharyngitis during the previous year were also reported to have received some form of treatment. The majority of treatments were received in government clinics (36.6%) and at home (26.3%). Half of treatments included an antibiotic. Nineteen students (0.5%) had clinically-apparent pharyngitis at screening. Conclusion: Pharyngitis is common among school-aged children and adolescents in Zambia, with females reporting significantly more sore throat episodes than males. Parents/guardians have variable knowledge about the frequency of sore throat in their children, and management of pharyngitis may be suboptimal for many children since more than a quarter were reported to have received treatment without skilled assessment. These results provide insight into current perceptions and practices related to sore throat in Zambia and will be used to design public awareness activities aimed at reducing RHD.
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    Pediatric systemic lupus erythematosus patients in South Africa have high prevalence and severity of cardiac and vascular manifestations
    (2019-11-26) Harrison, Michael J; Zühlke, Liesl J; Lewandowski, Laura B; Scott, Christiaan
    Abstract Background Pediatric onset of systemic lupus erythematosus (SLE) is associated with major organ involvement, and African patients tend to develop more aggressive disease than patients of European descent. Although cardiovascular involvement is common in pediatric SLE, there are few published reports on the subject. This study describes the frequency and characteristics of cardiac and vascular manifestations of pediatric SLE in a multi-ethnic South African cohort. Methods Demographic, clinical, and echocardiographic data were collected from pediatric SLE patients at two centers in Cape Town, South Africa. At the time of investigation, this cohort consisted of 93 participants diagnosed with SLE according to international classification criteria prior to the age of 19. Individuals with cardiac and/or vascular involvement were identified by retrospective chart review. Cardiac manifestations were defined as presence of pericardial effusion, myocarditis, cardiomyopathy, cardiac failure, Libman-Sacks endocarditis, myocardial infarction, and arrhythmia. Vascular manifestations included deep vein thrombosis, pulmonary embolism, sinus thrombosis, stroke, critical limb ischemia, cerebral vasculitis and systemic vasculitis. Statistical analysis was performed using R (v3.4.1). Results Cardiac and vascular involvement was present in 47% of the cohort. Previous studies have reported prevalence of 5%—50%. Demographic features of those with cardiac/vascular involvement did not differ from the overall cohort. Echocardiographic data were available for 23 participants. The most common cardiac manifestations were pericardial effusion (n = 24) and cardiac failure (n = 8), while the most common vascular manifestations were cerebral vasculitis (n = 9), stroke (n = 7), and pulmonary embolism (n = 7). Cardiovascular manifestations were frequently severe; one third of pericardial effusion cases required intervention, including three cases of cardiac tamponade. Cardiac and vascular involvement conferred an increased risk of mortality (31.1% versus 10.4%). Conclusions Cardiac and vascular involvement were highly prevalent in this South African cohort. The mortality rate was high, and severe manifestations were frequent. Prospective research is needed to improve knowledge of pediatric SLE in Africa and to improve outcomes for this high-risk population.
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    Prevalence of rheumatic heart disease in Zambian school children
    (BioMed Central, 2018-07-03) Schwaninger, Sherri; Musuku, John; Engel, Mark E; Musonda, Patrick; Lungu, Joyce C; Machila, Elizabeth; Mtaja, Agnes; Mulendele, Evans; Kavindele, Dorothy; Spector, Jonathan; Tadmor, Brigitta; Gutierrez, Marcelo M; Van Dam, Joris; Colin, Laurence; Long, Aidan; Fishman, Mark C; Mayosi, Bongani M; Zühlke, Liesl J
    Background The large global burden of rheumatic heart disease (RHD) has come to light in recent years following robust epidemiologic studies. As an operational research component of a broad program aimed at primary and secondary prevention of RHD, we sought to determine the current prevalence of RHD in the country’s capital, Lusaka, using a modern imaging-based screening methodology. In addition, we wished to evaluate the practicality of training local radiographers in echocardiography screening methods. Methods Echocardiography was conducted on a random sample of students in 15 schools utilizing a previously validated, abbreviated screening protocol. Through a task-shifting scheme, and in the spirit of capacity-building to enhance local diagnostic and research skills, general radiographers based at Lusaka University Teaching Hospital (UTH) were newly trained to use portable echocardiography devices. Students deemed as screen-positive were referred for comprehensive echocardiography and clinical examination at UTH. Cardiac abnormalities were classified according to standard World Heart Federation criteria. Results Of 1102 students that were consented and screened, 53 students were referred for confirmatory echocardiography. Three students had definite RHD, 10 had borderline RHD, 29 were normal, and 11 students were lost to follow-up. The rates of definite, borderline, and total RHD were 2.7 per 1000, 9.1 per 1000, and 11.8 per 1000, respectively. Anterior mitral valve leaflet thickening and chordal thickening were the most common morphological defects. The pairwise kappa test showed fair agreement between the local radiographers and an echocardiographer quality assurance specialist. Conclusion The prevalence of asymptomatic RHD in urban communities in Zambia is within the range of results reported in other sub-Saharan African countries using the WHF criteria. Task-shifting local radiographers to conduct echocardiography was feasible. The results of this study will be used to inform ongoing efforts in Zambia to control and eventually eliminate RHD. Trial registration The study was registered on clinicaltrials.gov ( #NCT02661763 ).
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    Prevalence, characteristics and additional stroke risk stratification: an analysis of the Atrial Fibrillation cohort within the REMEDY study
    (2017) Cupido, Blanche J; Mayosi, Bongani M; Zühlke, Liesl J
    Background: Atrial fibrillation (AF) is the most common arrhythmia and may be complicated by embolic stroke. It is also associated with a significant risk of heart failure and mortality. The burden of rheumatic heart disease remains great in the developing world. The prevalence of AF in those with rheumatic heart disease is in the order of 20% with a resultant 17-fold increased risk of embolic stroke. Over time, many other risk factors for stroke in the AF population have been described. Stroke risk stratification tools such as the CHADS₂ (Congestive heart failure, hypertension, age of 75 or older, diabetes mellitus or stroke/TIA) and CHA₂DS₂VASc (with the addition of a second age category, female gender, and peripheral artery disease) scores have been developed. These are used to assess the need for anticoagulation and have been well validated. These scores have traditionally excluded those patients with valvular AF. Valvular AF has not been studied extensively in the contemporary era. Oral anticoagulation had previously been advised in all patients with valvular AF. Little is known however about outcomes for stroke and mortality in this cohort of patients. Furthermore, the utilization of the CHADS₂ and CHA₂DS₂VASc scores may provide incremental benefit in prognostication and resultantly, both more diligent prescription of anticoagulation and improved outcomes. Objectives: The objectives of this study were as follows - 1. To determine the prevalence of AF in the Global Rheumatic Heart Disease Registry (the REMEDY study) and in the Groote Schuur Hospital (GSH) cohort. 2. To assess the demographic, social and clinical characteristics of patients with AF in the REMEDY study and in the GSH cohort. 3. To assess the frequency of CHADS₂ and CHA₂DS₂VASc risk factors in the GSH cohort and to calculate a CHADS₂ and CHA₂DS₂VASc score on each of the patients with AF. 4. To establish whether CHADS₂ and CHA₂DS₂VASc scores further increase the risk of stroke and death in this cohort of patients with valvular AF. Methods: This is a substudy of the Global Rheumatic Heart Disease Registry (the REMEDY study). We assessed those with AF from the entire cohort for prevalence and outcome data. Patients with ECG or Holter proven AF from the GSH cohort were further risk stratified using the CHADS₂ and CHA₂DS₂Vasc scores. Clinical data was obtained from folder reviews and telephonic interviews. The CHADS₂ and CHA₂DS₂Vasc scores for each patient in the GSH cohort were calculated. Patients were followed up for 2 years and information pertaining to death and stroke were obtained from folder reviews. These were then correlated with the CHADS₂ and CHA₂DS₂Vasc scores. Results: A total of 2624 REMEDY patients were analysed. Of these, 22% in the total cohort (586 of 2684 patients) and 38.2% in the GSH cohort (187 of 489 patients) had AF. These patients were older (35 years vs. 25 years, p<0.0001), more likely to be female (73.1% vs. 65.6%, p=0.001) and more frequently had a history of congestive heart disease (41.0% vs. 33.3%, p=0.001) when compared to those in sinus rhythm. They also had significantly more strokes (13.8% vs. 5%, p<0.0001) and a poorer NYHA class (NYHA III& IV 30.8% vs. 25.2%, p=0.002). The cohort with AF had more severely impaired left ventricular (LV) function compared to those in sinus rhythm (Ejection fraction (EF) 57% vs. 61%. P<0.0001). The presence of a larger left atrial (LA) size, spontaneous echo contrast and LA thrombus was much greater in the AF cohort. Of those patients in AF, only 68% had received a prescription for warfarin. The GSH cohort was risk stratified using the CHADS₂ and CHA₂DS₂VASc scores. Twenty-three percent of patients had a CHADS₂ score of 0 and 27.7% of 1. When the same cohort was scored using the CHA₂DS₂VASc score, only 5.4% had a score of 0; this difference was mainly driven by the additional category of female gender. The patients in our cohort were young (median age 28 years) and had few comorbidities. Despite this, patients with AF did significantly worse than those in sinus rhythm, with a stroke rate of 4.6% and a mortality rate of 13.1% observed at 2 years (compared to a 1.5% stroke rate and 5.5% mortality rate for those in sinus rhythm). The presence of any additional comorbidities significantly reduced survival in both the short and long term. Greater CHA₂DS₂VASc score categories (CHA₂DS₂VASc 1 and CHA₂DS₂VASc 2 or more) conferred an incrementally higher risk of death. Conclusion: In a contemporary cohort of patients with rheumatic heart disease, AF is common with a prevalence of 22-39%. These patients were older and exhibited features of more advanced disease both clinically and on echo, compared to their sinus rhythm counterparts. The mortality and stroke rates in the AF group were high despite the relatively young age of this cohort. Mortality and stroke increased significantly and incrementally with each greater CHA₂DS₂VASc score category. Given the differences in chronicity between RHD in the developed world (i.e., disease of older people) and RHD in developing countries (i.e., disease of the young), these results cannot be extrapolated to those living in the first world.
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    Standard echocardiography versus handheld echocardiography for the detection of subclinical rheumatic heart disease: A systematic review
    (2018) Telford, Lisa Helen; Engel, Mark E; Zühlke, Liesl J; Ochodo, Eleanor A
    Rheumatic heart disease (RHD) is a permanent heart valve condition resulting from an abnormal immune reaction to group A streptococcal (GAS) infection typically occurring in childhood. If left untreated, disease progression can result in irreversible heart valve damage, cardiac failure, stroke and premature death. Significantly, RHD is a preventable and treatable chronic condition which mostly effects disadvantaged populations across the world. Moreover, the continued persistence of RHD contributes to considerable amounts of preventable morbidity and mortality, predominantly among adolescents and young adults. The accurate detection of subclinical RHD in children and adolescents, however, remains hampered by the cost of diagnostic machinery and scarcity of trained personnel. Alternative RHD screening tests, which are both accurate and affordable, are therefore needed in many endemic areas. Recently, handheld echocardiography has become widely available with a variety of clinical uses. If shown to be sufficiently accurate, use of these handheld devices could potentially expand access to echocardiographic screening in RHD endemic areas. The research undertaken for this MPH dissertation compares the accuracy of handheld echocardiography for the detection of rheumatic heart disease to the reference standard using systematic review methods. The dissertation is structured into three parts. PART A is a research protocol which describes the background and process of the proposed review. This section details the quantitative methods to be used in the systematic review and meta-analysis of studies which assess the diagnostic accuracy of handheld echocardiography for rheumatic heart disease detection in children and adolescents. The proposed systematic review methods are based on those of the Cochrane Collaboration. PART B is an extended literature review which expands on some of the topics raised in the background section of the protocol. A more in depth insight into the context surrounding the proposed research is offered and its importance highlighted. By reviewing the current body of evidence, this literature review aimed to both describe and contextualise the global burden of rheumatic heart disease whilst providing a rationale for further research into better screening modalities. Similarly, it also sought to describe the importance of understanding rheumatic heart disease epidemiology so that future research and screening programmes may be targeted accordingly. PART C is a full systematic review of diagnostic test accuracy studies presented as a journal ‘ready’ manuscript in a format suitable for submission to PLoS ONE. The background to the systematic review is briefly summarised after which the results are then presented and discussed. The main findings, from seven included studies, provide some evidence for the potential of handheld echocardiography to increase access to echocardiographic screening for rheumatic heart disease. Lastly and in conclusion, implications arising from the findings of the review are posited and suggestions for future research offered.