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Dive into the research topics where Warren Stevens is active.

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Featured researches published by Warren Stevens.


BMJ | 2004

Antiretroviral therapy in Africa.

Warren Stevens; Steve Kaye; Tumani Corrah

We should stop and think about the risks of resistance, and ways of minimising them, before increasing access to antiretroviral therapy in Africa Demands for the introduction of antiretroviral therapy into Africa have been growing over the past few years. On the face of it, the availability of antiretroviral therapy at what seems to be an affordable price is good news. The treatment can produce dramatic clinical improvements in people with symptomatic HIV disease and, when used optimally, can delay the progression of disease. However, the potential short term gains from reducing individual morbidity and mortality may be far outweighed by the potential for the long term spread of drug resistance if the experience of adherence to treatment for tuberculosis is repeated. Without due forethought and planning, antiretroviral therapy is likely to be introduced to Africa in a random and haphazard way, with inconsistent prescribing practices and poor monitoring of therapy and adherence. This risks the rapid development and transmission of drug resistance. Virus strains with reduced sensitivity to zidovudine, the first drug used to treat HIV infection, were first observed in 1989, three years after it was introduced.1 Subsequently, resistance to every currently licensed antiretroviral drug has been observed.2 Drug resistance within an individual patient is not confined to a single compound, and cross resistance between drugs of the same class is the rule rather than the exception.3 Drug resistance arises by natural selection, mutant strains being selected when the virus replicates in sub-limiting drug concentrations. The only way to prevent resistance is to use a drug regimen that reduces virus replication to virtually zero (commonly equated with a plasma virus load below 50 RNA copies/ml). In this circumstance, the probability of a mutant arising to all the drugs used in a highly active antiretroviral therapy …


BMC Public Health | 2010

Epidemiological and economic burden of metabolic syndrome and its consequences in patients with hypertension in Germany, Spain and Italy; a prevalence-based model

Jürgen Scholze; Eduardo Alegria; Claudio Ferri; Sue Langham; Warren Stevens; David Jeffries; Kerstin Uhl-Hochgraeber

BackgroundThe presence of metabolic syndrome in patients with hypertension significantly increases the risk of cardiovascular disease, type 2 diabetes and mortality. Our aim is to estimate the epidemiological and economic burden to the health service of metabolic syndrome in patients with hypertension in three European countries in 2008 and 2020.MethodsAn age, sex and risk group structured prevalence based cost of illness model was developed using the United States Adult Treatment Panel III of the National Cholesterol Education Program criteria to define metabolic syndrome. Data sources included published information and public use databases on disease prevalence, incidence of cardiovascular events, prevalence of type 2 diabetes, treatment patterns and cost of management in Germany, Spain and Italy.ResultsThe prevalence of hypertension with metabolic syndrome in the general population of Germany, Spain and Italy was 36%, 11% and 10% respectively. In subjects with hypertension 61%, 22% and 21% also had metabolic syndrome. Incident cardiovascular events and attributable mortality were around two fold higher in subjects with metabolic syndrome and prevalence of type 2 diabetes was around six-fold higher. The economic burden to the health service of metabolic syndrome in patients with hypertension was been estimated at €24,427, €1,900 and €4,877 million in Germany, Spain and Italy and forecast to rise by 59%, 179% and 157% respectively by 2020. The largest components of costs included the management of prevalent type 2 diabetes and incident cardiovascular events. Mean annual costs per hypertensive patient were around three-fold higher in subjects with metabolic syndrome compared to those without and rose incrementally with the additional number of metabolic syndrome components present.ConclusionThe presence of metabolic syndrome in patients with hypertension significantly inflates economic burden and costs are likely to increase in the future due to an aging population and an increase in the prevalence of components of metabolic syndrome.


Bulletin of The World Health Organization | 2009

Meeting oxygen needs in Africa: an options analysis from the Gambia

Stephen R. C. Howie; Sarah Hill; Augustine Ebonyi; Gautam Krishnan; Ousman Njie; Momodou Sanneh; Mariatou Jallow; Warren Stevens; Kevin Taylor; Martin Weber; Pamela Collier Njai; Mary Tapgun; Tumani Corrah; Kim Mulholland; David Peel; Malick Njie; Philip C. Hill; Richard A. Adegbola

OBJECTIVE To compare oxygen supply options for health facilities in the Gambia and develop a decision-making algorithm for choosing oxygen delivery systems in Africa and the rest of the developing world. METHODS Oxygen cylinders and concentrators were compared in terms of functionality and cost. Interviews with key informants using locally developed and adapted WHO instruments, operational assessments, cost-modelling and cost measurements were undertaken to determine whether oxygen cylinders or concentrators were the better choice. An algorithm and a software tool to guide the choice of oxygen delivery system were constructed. FINDINGS In the Gambia, oxygen concentrators have significant advantages compared to cylinders where power is reliable; in other settings, cylinders are preferable as long as transporting them is feasible. Cylinder costs are greatly influenced by leakage, which is common, whereas concentrator costs are affected by the cost of power far more than by capital costs. Only two of 12 facilities in the Gambia were found suitable for concentrators; at the remaining 10 facilities, cylinders were the better option. CONCLUSION Neither concentrators nor cylinders are well suited to every situation, but a simple options assessment can determine which is better in each setting. Nationally this would result in improved supply and lower costs by comparison with conventional cylinders alone, although ensuring a reliable supply would remain a challenge. The decision algorithm and software tool designed for the Gambia could be applied in other developing countries.


BMC Public Health | 2013

Modeling health impact of global health programs implemented by Population Services International

Hongmei Yang; Susan Duvall; Amy Ratcliffe; David Jeffries; Warren Stevens

BackgroundGlobal health implementing organizations benefit most from health impact estimation models that isolate the individual effects of distributed products and services - a feature not typically found in intervention impact models, but which allow comparisons across interventions and intervention settings. Population Services International (PSI), a social marketing organization, has developed a set of impact models covering seven health program areas, which translate product/service distribution data into impact estimates. Each models primary output is the number of disability-adjusted life-years (DALYs) averted by an intervention within a specific country and population context. This paper aims to describe the structure and inputs for two types of DALYs averted models, considering the benefits and limitations of this methodology.MethodsPSI employs two modeling approaches for estimating health impact: a macro approach for most interventions and a micro approach for HIV, tuberculosis (TB), and behavior change communication (BCC) interventions. Within each intervention country context, the macro approach determines the coverage that one product/service unit provides a population in person-years, whereas the micro approach estimates an individuals risk of infection with and without the product/service unit. The models use these estimations to generate per unit DALYs averted coefficients for each intervention. When multiplied by program output data, these coefficients predict the total number of DALYs averted by an intervention in a country.ResultsModel outputs are presented by country for two examples: Water Chlorination DALYs Averted Model, a macro model, and the HIV Condom DALYs Averted Model for heterosexual transmission, a micro model. Health impact estimates measured in DALYs averted for PSI interventions on a global level are also presented.ConclusionsThe DALYs averted models offer implementing organizations practical measurement solutions for understanding an interventions contribution to improving health. These models calculate health impact estimates that reflect the scale and diversity of program operations and intervention settings, and that enable comparisons across health areas and countries. Challenges remain in accounting for intervention synergies, attributing impact to a single organization, and sourcing and updating model inputs. Nevertheless, these models demonstrate how DALYs averted can be viably used by the global health community as a metric for predicting intervention impact using standard program output data.


Journal of Research in Nursing | 1997

An evaluation of nursing development units

Sally Redfern; Charles Normand; Sara Christian; Annette Gilmore; Trevor Murrells; Ian Norman; Warren Stevens

The aims of this study, which is still in progress, are to assess the value that nursing development units add to nursing and health care and to describe the essence of an NDU. The areas investigated cover: resources and costs, research and audit activities, networking activities, staff morale, staff development and supervision, and clinical leadership. The research took a staged approach with four phases: consultation, profiling the NDUs, comparing NDUs with units without NDU status and case studies of five high-performing NDUs. This paper provides an overview of the study and findings from Phases 1-3. It was important for clinical leaders to be clinically credible, to have authority and to be free from day-to-day care provision and management. Quantitative differences between NDUs and comparison units emerged for research and dissemination activity (NDUs were more active), and sickness absence (more long-term sickness in NDUs) but not for audit and staff development activity, nor for the financial context. Data from the final phase will give a more detailed understanding of the significance of these differences and the different pathways that can be taken to achieving success as an NDU.


European Journal of Health Economics | 2011

Modelling the costs of care of hypertension in patients with metabolic syndrome and its consequences, in Germany, Spain and Italy

Eberhard Wille; Jürgen Scholze; Eduardo Alegria; Claudio Ferri; Sue Langham; Warren Stevens; David Jeffries; Kerstin Uhl-Hochgraeber

The presence of metabolic syndrome in patients with hypertension significantly increases the risk of cardiovascular disease, type 2 diabetes and mortality. Our aim is to estimate the economic burden to the health service of metabolic syndrome (MetS) in patients with hypertension and its consequences, in three European countries in 2008, and to forecast future economic burden in 2020 using projected demographic estimates and assumptions around the growth of MetS. An age-, sex- and risk group-structured prevalence-based cost of illness model was developed using the United States Adult Treatment Panel III of the National Cholesterol Education Program criteria to define MetS. Data sources included published information and public use databases on disease prevalence, incidence of cardiovascular events, prevalence of type 2 diabetes, treatment patterns and cost of management in Germany, Spain and Italy. The economic burden to the health service of MetS in patients with hypertension has been estimated at 24,427 €, 1,900 € and 4,877 € million in Germany, Spain and Italy, and is forecast to rise by 59, 179 and 157%, respectively, by 2020. The largest components of costs included the management of prevalent type 2 diabetes and incident cardiovascular events. Mean annual costs per hypertensive patient were around three-fold higher in subjects with MetS compared to those without and rose incrementally with the additional number of MetS components present. In conclusion, the presence of MetS in patients with hypertension significantly inflates economic burden, and costs are likely to increase in the future due to an aging population and an increase in the prevalence of components of MetS.


International Journal of Cardiology | 2003

National economic impact of tirofiban for unstable angina and myocardial infarction without ST elevation; example from the United Kingdom

Ameet Bakhai; Marcus Flather; Julian Collinson; Warren Stevens; Charles Normand; Evo Alemao; Robbin F. Itzler; Rami Ben-Joseph

BACKGROUND Acute coronary syndromes without ST elevation are a major health and economic burden. Treatments such as glycoprotein IIb/IIIa antagonists like tirofiban reduce the risk of complications but the cost impact of these agents including cost offsets of avoiding complications are needed particularly in Europe. METHODS We used treatment patterns from the Prospective Registry of Acute Ischemic Syndromes in the UK, risk reductions derived from the PRISM-PLUS trial and cost estimates from the CHKS database to estimate the impact of tirofiban on PRAIS-UK patients with and without complications and subgroups at higher risk of complications. These subgroups (and proportions) were patients: (1) aged 60 or over with abnormal electrocardiograms (58%), (2) with ST depression or bundle branch block on admission (30%) and (3) with ST depression, bundle branch block or MI on admission (37%). RESULTS Total cost of care in the UK at 6 months for the estimated 87339 acute coronary syndromes admissions annually was pound 213 million, which would increase by pound 33 million (15.7%) if tirofiban were given to all patients, avoiding 2422 complications at a mean cost per event avoided of pound 13388. Among the subgroups, the mean cost per event avoided ranges from pound 10856 for subgroup 1 to pound 5953 for subgroup 3. Treating the latter subgroup, would avoid 1977 events at a cost of pound 12 million (5.5%). CONCLUSION The use of tirofiban in the UK to treat acute coronary syndromes patients without ST elevation provides an important therapeutic advantage at modest proportional increase in cost, particularly if targeted to higher risk subgroups as recommended in the European guidelines.


Journal of Advanced Nursing | 2001

'More than just money'– widening the understanding of the costs involved in cancer care

Susie Pearce; Daniel Kelly; Warren Stevens


International Journal of Tuberculosis and Lung Disease | 2005

Risk factors for defaulting from tuberculosis treatment: a prospective cohort study of 301 cases in the Gambia.

Philip C. Hill; Warren Stevens; Sarah Hill; J. Bah; S. A. Donkor; A. Jallow; Christian Lienhardt


Social Science & Medicine | 2004

Optimisation versus certainty: understanding the issue of heterogeneity in economic evaluation

Warren Stevens; Charles Normand

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David Jeffries

Medical Research Council

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Sarah Hill

University of Edinburgh

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Tumani Corrah

Medical Research Council

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David Peel

East Sussex County Council

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Kevin Taylor

Medical Research Council

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