Mark E. Engel
University of Cape Town
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Featured researches published by Mark E. Engel.
BMC Medical Research Methodology | 2008
Salla Atkins; Simon Lewin; Helen Smith; Mark E. Engel; Atle Fretheim; Jimmy Volmink
BackgroundQualitative synthesis has become more commonplace in recent years. Meta-ethnography is one of several methods for synthesising qualitative research and is being used increasingly within health care research. However, many aspects of the steps in the process remain ill-defined.DiscussionWe utilized the seven stages of the synthesis process to synthesise qualitative research on adherence to tuberculosis treatment. In this paper we discuss the methodological and practical challenges faced; of particular note are the methods used in our synthesis, the additional steps that we found useful in clarifying the process, and the key methodological challenges encountered in implementing the meta-ethnographic approach.The challenges included shaping an appropriate question for the synthesis; identifying relevant studies; assessing the quality of the studies; and synthesising findings across a very large number of primary studies from different contexts and research traditions. We offer suggestions that may assist in undertaking meta-ethnographies in the future.SummaryMeta-ethnography is a useful method for synthesising qualitative research and for developing models that interpret findings across multiple studies. Despite its growing use in health research, further research is needed to address the wide range of methodological and epistemological questions raised by the approach.
European Heart Journal | 2015
Liesl Zühlke; Mark E. Engel; Ganesan Karthikeyan; Sumathy Rangarajan; Pam Mackie; Blanche Cupido; Katya Mauff; Shofiqul Islam; Alexia Joachim; Rezeen Daniels; Veronica Francis; Stephen Ogendo; Bernard Gitura; Charles Mondo; Emmy Okello; Peter Lwabi; Mohammed M. Al-Kebsi; Christopher Hugo-Hamman; Sahar S. Sheta; Abraham Haileamlak; Wandimu Daniel; Dejuma Yadeta Goshu; Senbeta G. Abdissa; Araya G. Desta; Bekele A. Shasho; Dufera M. Begna; Ahmed ElSayed; Ahmed S. Ibrahim; John Musuku; Fidelia Bode-Thomas
AIMS Rheumatic heart disease (RHD) accounts for over a million premature deaths annually; however, there is little contemporary information on presentation, complications, and treatment. METHODS AND RESULTS This prospective registry enrolled 3343 patients (median age 28 years, 66.2% female) presenting with RHD at 25 hospitals in 12 African countries, India, and Yemen between January 2010 and November 2012. The majority (63.9%) had moderate-to-severe multivalvular disease complicated by congestive heart failure (33.4%), pulmonary hypertension (28.8%), atrial fibrillation (AF) (21.8%), stroke (7.1%), infective endocarditis (4%), and major bleeding (2.7%). One-quarter of adults and 5.3% of children had decreased left ventricular (LV) systolic function; 23% of adults and 14.1% of children had dilated LVs. Fifty-five percent (n = 1761) of patients were on secondary antibiotic prophylaxis. Oral anti-coagulants were prescribed in 69.5% (n = 946) of patients with mechanical valves (n = 501), AF (n = 397), and high-risk mitral stenosis in sinus rhythm (n = 48). However, only 28.3% (n = 269) had a therapeutic international normalized ratio. Among 1825 women of childbearing age (12-51 years), only 3.6% (n = 65) were on contraception. The utilization of valvuloplasty and valve surgery was higher in upper-middle compared with lower-income countries. CONCLUSION Rheumatic heart disease patients were young, predominantly female, and had high prevalence of major cardiovascular complications. There is suboptimal utilization of secondary antibiotic prophylaxis, oral anti-coagulation, and contraception, and variations in the use of percutaneous and surgical interventions by country income level.
The Lancet | 2009
Nathan Ford; Jean B. Nachega; Mark E. Engel; Edward J Mills
BACKGROUND Directly observed therapy has been recommended to improve adherence for patients with HIV infection who are on highly active antiretroviral therapy, but the benefit and cost-effectiveness of this approach has not been established conclusively. We did a systematic review and meta-analysis of randomised trials of directly observed versus self-administered antiretroviral treatment. METHODS We did duplicate searches of databases (from inception to July 27, 2009), searchable websites of major HIV conferences (up to July, 2009), and lay publications and websites (March-July, 2009) to identify randomised trials assessing directly observed therapy to promote adherence to antiretroviral therapy in adults. Our primary outcome was virological suppression at study completion. We calculated relative risks (95% CIs), and pooled estimates using a random-effects method. FINDINGS 12 studies met our inclusion criteria; four of these were done in groups that were judged to be at high risk of poor adherence (drug users and homeless people). Ten studies reported on the primary outcome (n=1862 participants); we calculated a pooled relative risk of 1.04 (95% CI 0.91-1.20, p=0.55), and noted moderate heterogeneity between the studies (I(2)= 53.8%, 95% CI 0-75.7, p=0.0247) for directly observed versus self-administered treatment. INTERPRETATION Directly observed antiretroviral therapy seems to offer no benefit over self-administered treatment, which calls into question the use of such an approach to support adherence in the general patient population. FUNDING None.
PLOS ONE | 2011
Mark E. Engel; Raphaella Stander; Jonathan Vogel; Adebowale Adeyemo; Bongani M. Mayosi
Background Acute rheumatic fever is considered to be a heritable condition, but the magnitude of the genetic effect is unknown. The objective of this study was to conduct a systematic review and meta-analysis of twin studies of concordance of acute rheumatic fever in order to derive quantitative estimates of the size of the genetic effect. Methods We searched PubMed/MEDLINE, ISI Web of Science, EMBASE, and Google Scholar from their inception to 31 January 2011, and bibliographies of retrieved articles, for twin studies of the concordance for acute rheumatic fever or rheumatic heart disease in monozygotic versus dizygotic twins that used accepted diagnostic criteria for acute rheumatic fever and zygosity without age, gender or language restrictions. Twin similarity was measured by probandwise concordance rate and odds ratio (OR), and aggregate probandwise concordance risk was calculated by combining raw data from each study. ORs from separate studies were combined by random-effects meta-analysis to evaluate association between zygosity status and concordance. Heritability was estimated by fitting a variance components model to the data. Results 435 twin pairs from six independent studies met the inclusion criteria. The pooled probandwise concordance risk for acute rheumatic fever was 44% in monozygotic twins and 12% in dizygotic twins, and the association between zygosity and concordance was strong (OR 6.39; 95% confidence interval, 3.39 to 12.06; P<0.001), with no significant study heterogeneity (P = 0.768). The estimated heritability across all the studies was 60%. Conclusions Acute rheumatic fever is an autoimmune disorder with a high heritability. The discovery of all genetic susceptibility loci through whole genome scanning may provide a clinically useful genetic risk prediction tool for acute rheumatic fever and its sequel, rheumatic heart disease.
Circulation-cardiovascular Quality and Outcomes | 2013
James Irlam; Bongani M. Mayosi; Mark E. Engel; Thomas A. Gaziano
Background— Acute rheumatic fever and subsequent rheumatic heart disease remain significant in developing countries. We describe a cost-effective analysis of 7 strategies for the primary prevention of acute rheumatic fever and rheumatic heart disease in children presenting with pharyngitis in urban primary care clinics in South Africa. Methods and Results— We used a Markov model to assess the cost-effectiveness of treatment with intramuscular penicillin using each of the following strategies: (1) empirical (treat all); (2) positive throat culture (culture all); (3) clinical decision rule (CDR) score ≥2 (CDR 2+); (4) CDR score ≥3 (CDR 3+); (5) treating those with a CDR score ≥2 plus those with CDR score <2 and positive cultures (CDR 2+, culture CDR negatives); (6) treating those with a CDR score ≥3 plus those with CDR score <3 and positive cultures (CDR 3+, culture CDR negatives); and (7) treat none. The strategies ranked in order from lowest cost were treat all (
Circulation | 2016
Liesl Zühlke; Ganesan Karthikeyan; Mark E. Engel; Sumathy Rangarajan; Pam Mackie; Blanche Cupido-Katya Mauff; Shofiqul Islam; Rezeen Daniels; Veronica Francis; Stephen Ogendo; Bernard Gitura; Charles Mondo; Emmy Okello; Peter Lwabi; Mohammed M. Al-Kebsi; Christopher Hugo-Hamman; Sahar S. Sheta; Abraham Haileamlak; Wandimu Daniel; Dejuma Yadeta Goshu; Senbeta G. Abdissa; Araya G. Desta; Bekele A. Shasho; Dufera M. Begna; Ahmed ElSayed; Ahmed S. Ibrahim; John Musuku; Fidelia Bode-Thomas; Christopher C. Yilgwan; Ganiyu Amusa
11.19 per child), CDR 2+ (
American Heart Journal | 2012
Ganesan Karthikeyan; Liesl Zühlke; Mark E. Engel; Sumathy Rangarajan; Salim Yusuf; Koon K. Teo; Bongani M. Mayosi
11.20); the CDR 3+ (
Cardiovascular Journal of Africa | 2016
David A. Watkins; Liesl Zühlke; Mark E. Engel; Rezeen Daniels; Veronica Francis; Gasnat Shaboodien; Mabvuto Kango; Azza Abul-Fadl; Abiodun M. Adeoye; Sulafa Ali; Mohammed M. Al-Kebsi; Fidelia Bode-Thomas; Gene Bukhman; Albertino Damasceno; Dejuma Yadeta Goshu; Alaa Elghamrawy; Bernard Gitura; Abraham Haileamlak; Abraha Hailu; Christopher Hugo-Hamman; Steve Justus; Ganesan Karthikeyan; Neil Kennedy; Peter Lwabi; Yoseph Mamo; Pindile Mntla; Christopher Sutton; Ana Olga Mocumbi; Charles Mondo; Agnes Mtaja
13.00); CDR 2+, culture CDR negatives (
Heart | 2015
Mark E. Engel; Abraham Haileamlak; Liesl Zühlke; Carolina Elisabet Lemmer; Simpiwe Nkepu; Marnie van de Wall; Wandimu Daniel; Maylene Shung King; Bongani M. Mayosi
16.42); CDR 3+, culture CDR negatives (
The Lancet Diabetes & Endocrinology | 2016
Mahmoud Werfalli; Mark E. Engel; Alfred Musekiwa; Andre Pascal Kengne; Naomi S. Levitt
23.89); and culture all (