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)

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

A MIXED-INTEGER MODEL PREDICTIVE CONTROL FORMULATION FOR LINEAR SYSTEMS

Most industrial model predictive controllers (MPC) use the traditional two-layer structure developed in the early 1980’s, where the upper layer defines optimal steady-state targets for inputs and outputs, while the lower layer calculates the control moves that drive the system towards these steady-state targets. Typically both layers use continuous quadratic programming (QP) formulations to derive the optimal solutions. On the other hand, advances in mixed-integer programming (MIP) algorithms and their successful application to solve large scheduling problems in reasonable time show that MIP formulations have the potential of being applied advantageously to the multivariable model predictive control problem. In this paper, we present mixed-integer quadratic programming (MIQP) formulations for both layers and show that several difficulties faced in the MPC practical implementation can be overcome with this approach. In particular, it is possible to set explicit priorities for inputs and outputs, define minimum moves to overcome hysteresis, and deal with digital or integer inputs. The proposed formulation is applied to 2 benchmark problems and to a simulated industrial system and the results compared with those achieved by a traditional continuous MPC. The solutions of the MIQP problems are derived by a computer implementation of the Outer Approximation method (OA) also developed as part of this work

IDENTIFICACIÓN MULTIVARIABLE DE CIRCUITO CERRADO CON OBLIGADO CONTROL DE MPC: CASO-ESTUDIO EN UN DISTRIBUIDOR C3/C4

This paper deals with the model re-identification in closed-loop systems with already existing MPC controllers. lt is assumed that the controller has a two-layer structure where the upper layer performs a simplified economic optimization in which the economic objective is represented as a linear combination of the process inputs. This is the case of several commercial MPC packages applied in industry. This work focuses on the case where the existing process model shows signs of deterioration and there is benefit in obtaining a new model. It is proposed a methodology where the test signal is introduced in the coefficients of the objective function of the economic layer. The approach allows the continuous operation of the system as the process constraints and product specification can be satisfied during the test. The application of the method is illustrated by simulation on a C3/C4 splitter of the oil industry. The method is simple to be implemented in existing commercial packages, and the results show that tne method has a good potential to be applied in practice.Este artículo trata sobre el modelo de re- identificación en sistemas de circuito cerrado con controladores MPC ya existentes. LT se supone que el controlador tiene una estructura de dos capas donde la capa superior realiza una optimización económica simplificado en el que el objetivo económico se representa como una combinación lineal de las entradas del proceso . Este es el caso de varios paquetes MPC comerciales aplicadas en la industria. Este trabajo se centra en el caso de que el modelo de proceso existente muestra signos de deterioro y existe un beneficio en la obtención de un nuevo modelo. Se propone una metodología donde se introduce la señal de prueba en los coeficientes de la función objetivo de la capa económica . El enfoque permite la operación continua del sistema como las limitaciones del proceso y especificación de producto puede ser satisfecha durante la prueba . La aplicación del método se ilustra por simulación en un divisor de C3/C4 de la industria del petróleo . El método es simple de implementar en los paquetes comerciales existentes , y los resultados muestran que el método tiene un buen potencial de ser aplicado en la práctic

Closed-loop model re-identification of processes under MPC with zone control

This work deals with a procedure for model re-identification of a process in closed loop with ail already existing commercial MPC. The controller considered here has a two-layer structure where the upper layer performs a target calculation based on a simplified steady-state optimization of the process. Here, it is proposed a methodology where a test signal is introduced in a tuning parameter of the target calculation layer. When the outputs are controlled by zones instead of at fixed set points, the approach allows the continuous operation of the process without an excessive disruption of the operating objectives as process constraints and product specifications remain satisfied during the identification test. The application of the method is illustrated through the simulation of two processes of the oil refining industry. (c) 2008 Elsevier Ltd. All rights reserved.Fundacao Universidade de Sao Paulo (FUSP)PETROBRAS[0050.0014884.05.2