Laser shallow melting of p-type silicon wafers as substrates for tunnel junctions in tandem solar cells

Tese de mestrado integrado, Engenharia da Energia e do Ambiente , 2022, Universidade de Lisboa, Faculdade de CiênciasThe fabrication of tandem solar cells requires a specific connectivity between layers, with specific characteristics such as the case of a tunnel junction that is made of two heavily doped narrow layers of different doping types (e.g. Phosphorus and Boron). When a certain amount of voltage is applied to the edges of the tunnel junction, the result is the alignment of both valence and conduction bands of the different subregions, enabling the electron flux from one cell to another without the need to energy variation of the electron. The Gas Immersion Laser Doping (GILD) technique uses a laser as the source of radiation and a dopant gas. A silicon wafer is inserted inside a compartment with a controlled atmosphere saturated with the doping gas, which receives energy from the laser as pulsed beams, melting and solidifying into a very fast process. When the melting occurs, the dopants penetrate the wafer and remain there upon solidification. When a high concentration of the dopant is confined inside an ultra-shallow depth of the wafer, the probability of forming a tunnel junction is increased. Therefore, before implementing this process, it is necessary to study the interaction between the laser and silicon samples. The purpose of this dissertation is to test and pre-select sample areas that were submitted to an infrared laser irradiation, varying on different sets of parameters, such has laser scan speed, number of scans, infrared transparent window type, among others. Samples will be evaluated regarding their topography, in terms of surface and in-depth melt homogeneity. These samples will be used as tests for the objective of the project in which this dissertation is inserted. The final goal of the project is thus to develop a process of tunnel junction formation with recurse to the GILD technique, using POCl3 as the dopant source and to create abrupt n++/p+ doping profiles (with 10 nm wide). The approach should lead to a scalable and low-cost industrial process for forming tunnel junctions directly integrated in tandem solar cells. Optical analysis of laser interaction on the silicon surface can be notable in slower laser scan speed for more than one successive scattering process. The results show an effective laser processed areas in a p-type Cz-Si wafer rather than in an emitter p++ on an p+ Cz-Si wafer. The chamber and the window that confines the sample in a controlled atmosphere affects positively the melting process when using a Quartz material rather than the Polycarbonate window.A evolução tecnológica tem permitido arranjar solução eficazes para combater a produção de energia à base de combustíveis fósseis. As energias renováveis estão a ser cada vez mais implementadas como fontes de conversão de energia primária para autoconsumo e distribuição na rede. A variabilidade e a inconstância que as fontes de energia renovável apresentam, devem ser colmatadas pontualmente por fontes alternativas ou convencionais de produção de energia, para garantir ao consumidor final de energia a sua utilização. Por definição, uma célula fotovoltaica é um dispositivo elétrico que é afetado pela exposição a certos tipos de radiação, resultando num diferencial em características como a corrente e a tensão. Baseia-se num efeito químico e físico, denominado por efeito fotovoltaico. Através da absorção de fotões por parte de um material semiconductor, ocorre a excitação dos seus eletrões e, consequentemente, a separação do respetivo átomo. É gerada uma diferença de potencial elétrico proporcionada pela separação das cargas. A radiação proveniente do sol é um recurso muito explorado atualmente, para produção de energia de fonte renovável. A irradiância espetral atinge valores máximos na região do infravermelho, permitindo correlacionar o grande destaque que o silício detém no mercado fotovoltaico, já que o intervalo de banda do mesmo encontra-se na região infravermelha, onde converte de forma eficiente grandes quantidades de radiação. O aproveitamento das restantes regiões do espetro solar deverá ser considerado para a implementação nas futuras células solares. O empilhamento de camadas de diferentes materiais, permite abranger uma maior banda de comprimento de onda. A célula de topo permite absorver intervalos de banda superiores, enquanto os fotões que não são absorvidos percorrem a junção até chegar à célula base, onde irá ocorrer a conversão de energia. Uma célula solar tandem como é o caso da perovskita/silício resulta numa célula mais eficiente em que são aproveitados os fotões de diferentes regiões do espetro solar. As células solares tandem são compostas por diferentes sub-células que têm intervalos de banda do espetro solar distintos. Permitem uma maior absorção de fotões pois abrangem um maior intervalo do comprimento de onda. A sua fabricação requer uma interligação complexa entre ambas as camadas denominadas por junção de túnel. Trata-se de uma região altamente dopada com duas camadas com concentração de dopantes distintos, como por exemplo Boro e Fósforo. Ambas as bandas de valência e condução das diferentes camadas alinham-se, possibilitando o fluxo de eletrões entre ambas sem necessidade de o fotão variar a sua energia. O silício é o material semiconductor mais utilizado para o fabrico de células solares. Consoante o seu grau de cristalinidade, poderá apresentar diferentes eficiências e consequentemente, custos, face à complexidade dos processos em que é submetido. A maioria dos módulos fotovoltaicos utilizados nas centrais são do tipo monocristalino, apresentando uma maior eficiência comparativamente às outras células de primeira geração. A eficiência da tecnologia fotovoltaica pode ser maximizada através de um processo denominado por dopagem. Ao introduzir impurezas em amostras, como por exemplo de silício, a conversão de energia é realizada de forma mais eficaz devido à alteração das propriedades elétricas. Dependendo da natureza das impurezas que serão inseridas nas amostras, será possível obter amostras do tipo p ou do tipo n. A alteração da cristalinidade de uma bolacha de silício afetará as ligações covalentes entre os átomos. A liberdade de movimento de um eletrão em amostras do tipo n, aumentará a condutividade e, consequentemente, a eficiência da célula num todo. A técnica GILD (Gas Immersion Laser Doping) é uma das alternativas para realizar processos de dopagem em silício. É utilizado um laser pulsado como fonte principal de radiação e uma atmosfera com um gás dopante. A amostra de silício permanece confinada num compartimento que possibilite criar uma atmosfera controlada com alta concentração de gás dopante. O laser pulsado incide na superfície da amostra proporcionando a fusão e solidificação intercalada, num processo extremamente rápido. Durante a fusão do silício, o dopante penetra a amostra, que permanece em profundidade quando ocorre a solidificação. Uma elevada concentração de dopante alocada numa camada ultra-fina, propicia a formação de uma junção de túnel. De forma a maximizar a eficácia da dopagem para o resultado pretendido, é fundamental analisar a interação entre o laser e o silício, e todos os fatores que estão associados. A técnica SEM (Scanning Electron Microscopy) é bastante utilizada para estudar a topografia de células após a interação direta com fontes de energia muito elevadas. Um feixe primário de eletrões é disparado diretamente na superfície da amostra que, após o contacto, resulta na emissão de eletrões secundários. Estes são armazenados e filtrados por um sistema de deteção que, consequentemente, irá correlacionar a variação na topografia da superfície amostral. O estudo da interação entre fontes de energia e amostras de silício é fundamental de modo a compreender a os fatores que possibilitam uma melhor homogeneidade superficial. O principal objetivo desta dissertação é testar, analisar e escolher as áreas amostrais que serão submetidas a um processo de irradiação recorrendo a um laser infravermelho, variando um conjunto de parâmetros, tais como, a velocidade de varrimento do laser, o número de repetições de cada ciclo de varrimento, o material que constitui a janela onde incide o laser, entre outros. Futuramente, as amostras que forem escolhidas, serão avaliadas relativamente à sua topografia, tanto em termos superficiais, como na fusão homogénea em profundidade. As amostras serão utilizadas como amostras teste para o objetivo do projeto em que esta dissertação se insere. O projeto tem a finalidade de desenvolver o processo de formação de junções de túnel pelo método de Gas Immersion Laser Doping utilizando como gás dopante o POCl3, de forma a criar uma camada ultra-fina e altamente dopada do tipo n (n++) através de toda a bolacha de silício. Um estudo preliminar acerca da interação entre laser e silício permite compreender de que maneira os vários fatores, tal como o tipo de equipamento, parâmetros e o tipo de amostra de silício utilizada, influenciam a homogeneidade do processo de fusão. Foram estudados e analisados os diferentes resultados comparando diretamente as várias variáveis. O material que constituía a janela onde incidia o laser, a velocidade de varrimento do pulso, a distância entre pontos focais (sucessivos e verticais) e a repetição do varrimento do laser, as diferentes amostras (emissor p++/p+ e bolacha p+, ambos de silício), foram comparados no âmbito desta dissertação. O processo de fabricação deverá conduzir a um método escalável e de baixo custo na produção industrial de junções de túnel para integrar nas células solares tandem. Numa análise microscópica das diferentes áreas amostrais é possível observar que a velocidade de varrimento do laser e o número de repetições dos ciclos de varrimento são as variáveis que mais influenciam na eficácia da fusão do silício. Em velocidades mais baixas do feixe do laser, é possível obter uma maior área cujo laser interagiu com sucesso. Mesmo que existam pequenas zonas escuras, a sucessiva repetição do processo resulta numa correção da zona não tratada. Num emissor sobre um wafer dopado (p++/p+) a interação do laser tornou-se numa fusão deficiente da superfície face à bolacha padrão (bolacha de silício tipo p). A grande concentração de boro na camada superior afeta negativamente a eficácia do processo de varrimento. A fusão homogénea do silício foi afetada positivamente quando utilizada uma janela de Quartzo como superfície transparente que permite a incidência do laser. Face à janela de policarbonato, os fatores óticos dos dois tipos de materiais, são notavelmente relevantes nos resultados obtidos

Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.

BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700

Why Are Outcomes Different for Registry Patients Enrolled Prospectively and Retrospectively? Insights from the Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF).

Background: Retrospective and prospective observational studies are designed to reflect real-world evidence on clinical practice, but can yield conflicting results. The GARFIELD-AF Registry includes both methods of enrolment and allows analysis of differences in patient characteristics and outcomes that may result. Methods and Results: Patients with atrial fibrillation (AF) and ≥1 risk factor for stroke at diagnosis of AF were recruited either retrospectively (n = 5069) or prospectively (n = 5501) from 19 countries and then followed prospectively. The retrospectively enrolled cohort comprised patients with established AF (for a least 6, and up to 24 months before enrolment), who were identified retrospectively (and baseline and partial follow-up data were collected from the emedical records) and then followed prospectively between 0-18 months (such that the total time of follow-up was 24 months; data collection Dec-2009 and Oct-2010). In the prospectively enrolled cohort, patients with newly diagnosed AF (≤6 weeks after diagnosis) were recruited between Mar-2010 and Oct-2011 and were followed for 24 months after enrolment. Differences between the cohorts were observed in clinical characteristics, including type of AF, stroke prevention strategies, and event rates. More patients in the retrospectively identified cohort received vitamin K antagonists (62.1% vs. 53.2%) and fewer received non-vitamin K oral anticoagulants (1.8% vs . 4.2%). All-cause mortality rates per 100 person-years during the prospective follow-up (starting the first study visit up to 1 year) were significantly lower in the retrospective than prospectively identified cohort (3.04 [95% CI 2.51 to 3.67] vs . 4.05 [95% CI 3.53 to 4.63]; p = 0.016). Conclusions: Interpretations of data from registries that aim to evaluate the characteristics and outcomes of patients with AF must take account of differences in registry design and the impact of recall bias and survivorship bias that is incurred with retrospective enrolment. Clinical Trial Registration: - URL: http://www.clinicaltrials.gov . Unique identifier for GARFIELD-AF (NCT01090362)

CMS physics technical design report : Addendum on high density QCD with heavy ions

Peer reviewe

The Changing Landscape for Stroke\ua0Prevention in AF: Findings From the GLORIA-AF Registry Phase 2

Background GLORIA-AF (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients with Atrial Fibrillation) is a prospective, global registry program describing antithrombotic treatment patterns in patients with newly diagnosed nonvalvular atrial fibrillation at risk of stroke. Phase 2 began when dabigatran, the first non\u2013vitamin K antagonist oral anticoagulant (NOAC), became available. Objectives This study sought to describe phase 2 baseline data and compare these with the pre-NOAC era collected during phase 1. Methods During phase 2, 15,641 consenting patients were enrolled (November 2011 to December 2014); 15,092 were eligible. This pre-specified cross-sectional analysis describes eligible patients\u2019 baseline characteristics. Atrial fibrillation disease characteristics, medical outcomes, and concomitant diseases and medications were collected. Data were analyzed using descriptive statistics. Results Of the total patients, 45.5% were female; median age was 71 (interquartile range: 64, 78) years. Patients were from Europe (47.1%), North America (22.5%), Asia (20.3%), Latin America (6.0%), and the Middle East/Africa (4.0%). Most had high stroke risk (CHA2DS2-VASc [Congestive heart failure, Hypertension, Age  6575 years, Diabetes mellitus, previous Stroke, Vascular disease, Age 65 to 74 years, Sex category] score  652; 86.1%); 13.9% had moderate risk (CHA2DS2-VASc = 1). Overall, 79.9% received oral anticoagulants, of whom 47.6% received NOAC and 32.3% vitamin K antagonists (VKA); 12.1% received antiplatelet agents; 7.8% received no antithrombotic treatment. For comparison, the proportion of phase 1 patients (of N = 1,063 all eligible) prescribed VKA was 32.8%, acetylsalicylic acid 41.7%, and no therapy 20.2%. In Europe in phase 2, treatment with NOAC was more common than VKA (52.3% and 37.8%, respectively); 6.0% of patients received antiplatelet treatment; and 3.8% received no antithrombotic treatment. In North America, 52.1%, 26.2%, and 14.0% of patients received NOAC, VKA, and antiplatelet drugs, respectively; 7.5% received no antithrombotic treatment. NOAC use was less common in Asia (27.7%), where 27.5% of patients received VKA, 25.0% antiplatelet drugs, and 19.8% no antithrombotic treatment. Conclusions The baseline data from GLORIA-AF phase 2 demonstrate that in newly diagnosed nonvalvular atrial fibrillation patients, NOAC have been highly adopted into practice, becoming more frequently prescribed than VKA in Europe and North America. Worldwide, however, a large proportion of patients remain undertreated, particularly in Asia and North America. (Global Registry on Long-Term Oral Antithrombotic Treatment in Patients With Atrial Fibrillation [GLORIA-AF]; NCT01468701

Height and body-mass index trajectories of school-aged children and adolescents from 1985 to 2019 in 200 countries and territories: a pooled analysis of 2181 population-based studies with 65 million participants

Summary Background Comparable global data on health and nutrition of school-aged children and adolescents are scarce. We aimed to estimate age trajectories and time trends in mean height and mean body-mass index (BMI), which measures weight gain beyond what is expected from height gain, for school-aged children and adolescents. Methods For this pooled analysis, we used a database of cardiometabolic risk factors collated by the Non-Communicable Disease Risk Factor Collaboration. We applied a Bayesian hierarchical model to estimate trends from 1985 to 2019 in mean height and mean BMI in 1-year age groups for ages 5–19 years. The model allowed for non-linear changes over time in mean height and mean BMI and for non-linear changes with age of children and adolescents, including periods of rapid growth during adolescence. Findings We pooled data from 2181 population-based studies, with measurements of height and weight in 65 million participants in 200 countries and territories. In 2019, we estimated a difference of 20 cm or higher in mean height of 19-year-old adolescents between countries with the tallest populations (the Netherlands, Montenegro, Estonia, and Bosnia and Herzegovina for boys; and the Netherlands, Montenegro, Denmark, and Iceland for girls) and those with the shortest populations (Timor-Leste, Laos, Solomon Islands, and Papua New Guinea for boys; and Guatemala, Bangladesh, Nepal, and Timor-Leste for girls). In the same year, the difference between the highest mean BMI (in Pacific island countries, Kuwait, Bahrain, The Bahamas, Chile, the USA, and New Zealand for both boys and girls and in South Africa for girls) and lowest mean BMI (in India, Bangladesh, Timor-Leste, Ethiopia, and Chad for boys and girls; and in Japan and Romania for girls) was approximately 9–10 kg/m2. In some countries, children aged 5 years started with healthier height or BMI than the global median and, in some cases, as healthy as the best performing countries, but they became progressively less healthy compared with their comparators as they grew older by not growing as tall (eg, boys in Austria and Barbados, and girls in Belgium and Puerto Rico) or gaining too much weight for their height (eg, girls and boys in Kuwait, Bahrain, Fiji, Jamaica, and Mexico; and girls in South Africa and New Zealand). In other countries, growing children overtook the height of their comparators (eg, Latvia, Czech Republic, Morocco, and Iran) or curbed their weight gain (eg, Italy, France, and Croatia) in late childhood and adolescence. When changes in both height and BMI were considered, girls in South Korea, Vietnam, Saudi Arabia, Turkey, and some central Asian countries (eg, Armenia and Azerbaijan), and boys in central and western Europe (eg, Portugal, Denmark, Poland, and Montenegro) had the healthiest changes in anthropometric status over the past 3·5 decades because, compared with children and adolescents in other countries, they had a much larger gain in height than they did in BMI. The unhealthiest changes—gaining too little height, too much weight for their height compared with children in other countries, or both—occurred in many countries in sub-Saharan Africa, New Zealand, and the USA for boys and girls; in Malaysia and some Pacific island nations for boys; and in Mexico for girls. Interpretation The height and BMI trajectories over age and time of school-aged children and adolescents are highly variable across countries, which indicates heterogeneous nutritional quality and lifelong health advantages and risks

Diminishing benefits of urban living for children and adolescents’ growth and development

Optimal growth and development in childhood and adolescence is crucial for lifelong health and well-being1–6. Here we used data from 2,325 population-based studies, with measurements of height and weight from 71 million participants, to report the height and body-mass index (BMI) of children and adolescents aged 5–19 years on the basis of rural and urban place of residence in 200 countries and territories from 1990 to 2020. In 1990, children and adolescents residing in cities were taller than their rural counterparts in all but a few high-income countries. By 2020, the urban height advantage became smaller in most countries, and in many high-income western countries it reversed into a small urban-based disadvantage. The exception was for boys in most countries in sub-Saharan Africa and in some countries in Oceania, south Asia and the region of central Asia, Middle East and north Africa. In these countries, successive cohorts of boys from rural places either did not gain height or possibly became shorter, and hence fell further behind their urban peers. The difference between the age-standardized mean BMI of children in urban and rural areas was <1.1 kg m–2 in the vast majority of countries. Within this small range, BMI increased slightly more in cities than in rural areas, except in south Asia, sub-Saharan Africa and some countries in central and eastern Europe. Our results show that in much of the world, the growth and developmental advantages of living in cities have diminished in the twenty-first century, whereas in much of sub-Saharan Africa they have amplified

Risk profiles and one-year outcomes of patients with newly diagnosed atrial fibrillation in India: Insights from the GARFIELD-AF Registry.

BACKGROUND: The Global Anticoagulant Registry in the FIELD-Atrial Fibrillation (GARFIELD-AF) is an ongoing prospective noninterventional registry, which is providing important information on the baseline characteristics, treatment patterns, and 1-year outcomes in patients with newly diagnosed non-valvular atrial fibrillation (NVAF). This report describes data from Indian patients recruited in this registry. METHODS AND RESULTS: A total of 52,014 patients with newly diagnosed AF were enrolled globally; of these, 1388 patients were recruited from 26 sites within India (2012-2016). In India, the mean age was 65.8 years at diagnosis of NVAF. Hypertension was the most prevalent risk factor for AF, present in 68.5% of patients from India and in 76.3% of patients globally (P < 0.001). Diabetes and coronary artery disease (CAD) were prevalent in 36.2% and 28.1% of patients as compared with global prevalence of 22.2% and 21.6%, respectively (P < 0.001 for both). Antiplatelet therapy was the most common antithrombotic treatment in India. With increasing stroke risk, however, patients were more likely to receive oral anticoagulant therapy [mainly vitamin K antagonist (VKA)], but average international normalized ratio (INR) was lower among Indian patients [median INR value 1.6 (interquartile range {IQR}: 1.3-2.3) versus 2.3 (IQR 1.8-2.8) (P < 0.001)]. Compared with other countries, patients from India had markedly higher rates of all-cause mortality [7.68 per 100 person-years (95% confidence interval 6.32-9.35) vs 4.34 (4.16-4.53), P < 0.0001], while rates of stroke/systemic embolism and major bleeding were lower after 1 year of follow-up. CONCLUSION: Compared to previously published registries from India, the GARFIELD-AF registry describes clinical profiles and outcomes in Indian patients with AF of a different etiology. The registry data show that compared to the rest of the world, Indian AF patients are younger in age and have more diabetes and CAD. Patients with a higher stroke risk are more likely to receive anticoagulation therapy with VKA but are underdosed compared with the global average in the GARFIELD-AF. CLINICAL TRIAL REGISTRATION-URL: http://www.clinicaltrials.gov. Unique identifier: NCT01090362

Improved risk stratification of patients with atrial fibrillation: an integrated GARFIELD-AF tool for the prediction of mortality, stroke and bleed in patients with and without anticoagulation.

OBJECTIVES: To provide an accurate, web-based tool for stratifying patients with atrial fibrillation to facilitate decisions on the potential benefits/risks of anticoagulation, based on mortality, stroke and bleeding risks. DESIGN: The new tool was developed, using stepwise regression, for all and then applied to lower risk patients. C-statistics were compared with CHA2DS2-VASc using 30-fold cross-validation to control for overfitting. External validation was undertaken in an independent dataset, Outcome Registry for Better Informed Treatment of Atrial Fibrillation (ORBIT-AF). PARTICIPANTS: Data from 39 898 patients enrolled in the prospective GARFIELD-AF registry provided the basis for deriving and validating an integrated risk tool to predict stroke risk, mortality and bleeding risk. RESULTS: The discriminatory value of the GARFIELD-AF risk model was superior to CHA2DS2-VASc for patients with or without anticoagulation. C-statistics (95% CI) for all-cause mortality, ischaemic stroke/systemic embolism and haemorrhagic stroke/major bleeding (treated patients) were: 0.77 (0.76 to 0.78), 0.69 (0.67 to 0.71) and 0.66 (0.62 to 0.69), respectively, for the GARFIELD-AF risk models, and 0.66 (0.64-0.67), 0.64 (0.61-0.66) and 0.64 (0.61-0.68), respectively, for CHA2DS2-VASc (or HAS-BLED for bleeding). In very low to low risk patients (CHA2DS2-VASc 0 or 1 (men) and 1 or 2 (women)), the CHA2DS2-VASc and HAS-BLED (for bleeding) scores offered weak discriminatory value for mortality, stroke/systemic embolism and major bleeding. C-statistics for the GARFIELD-AF risk tool were 0.69 (0.64 to 0.75), 0.65 (0.56 to 0.73) and 0.60 (0.47 to 0.73) for each end point, respectively, versus 0.50 (0.45 to 0.55), 0.59 (0.50 to 0.67) and 0.55 (0.53 to 0.56) for CHA2DS2-VASc (or HAS-BLED for bleeding). Upon validation in the ORBIT-AF population, C-statistics showed that the GARFIELD-AF risk tool was effective for predicting 1-year all-cause mortality using the full and simplified model for all-cause mortality: C-statistics 0.75 (0.73 to 0.77) and 0.75 (0.73 to 0.77), respectively, and for predicting for any stroke or systemic embolism over 1 year, C-statistics 0.68 (0.62 to 0.74). CONCLUSIONS: Performance of the GARFIELD-AF risk tool was superior to CHA2DS2-VASc in predicting stroke and mortality and superior to HAS-BLED for bleeding, overall and in lower risk patients. The GARFIELD-AF tool has the potential for incorporation in routine electronic systems, and for the first time, permits simultaneous evaluation of ischaemic stroke, mortality and bleeding risks. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier for GARFIELD-AF (NCT01090362) and for ORBIT-AF (NCT01165710)

Two-year outcomes of patients with newly diagnosed atrial fibrillation: results from GARFIELD-AF.

AIMS: The relationship between outcomes and time after diagnosis for patients with non-valvular atrial fibrillation (NVAF) is poorly defined, especially beyond the first year. METHODS AND RESULTS: GARFIELD-AF is an ongoing, global observational study of adults with newly diagnosed NVAF. Two-year outcomes of 17 162 patients prospectively enrolled in GARFIELD-AF were analysed in light of baseline characteristics, risk profiles for stroke/systemic embolism (SE), and antithrombotic therapy. The mean (standard deviation) age was 69.8 (11.4) years, 43.8% were women, and the mean CHA2DS2-VASc score was 3.3 (1.6); 60.8% of patients were prescribed anticoagulant therapy with/without antiplatelet (AP) therapy, 27.4% AP monotherapy, and 11.8% no antithrombotic therapy. At 2-year follow-up, all-cause mortality, stroke/SE, and major bleeding had occurred at a rate (95% confidence interval) of 3.83 (3.62; 4.05), 1.25 (1.13; 1.38), and 0.70 (0.62; 0.81) per 100 person-years, respectively. Rates for all three major events were highest during the first 4 months. Congestive heart failure, acute coronary syndromes, sudden/unwitnessed death, malignancy, respiratory failure, and infection/sepsis accounted for 65% of all known causes of death and strokes for <10%. Anticoagulant treatment was associated with a 35% lower risk of death. CONCLUSION: The most frequent of the three major outcome measures was death, whose most common causes are not known to be significantly influenced by anticoagulation. This suggests that a more comprehensive approach to the management of NVAF may be needed to improve outcome. This could include, in addition to anticoagulation, interventions targeting modifiable, cause-specific risk factors for death. CLINICAL TRIAL REGISTRATION: http://www.clinicaltrials.gov. Unique identifier: NCT01090362