Análisis automatizado de la calidad del conjunto mínimo de datos básicos. Implicaciones para los sistemas de ajuste de riesgos

ResumenFundamentosJunto a la edad del paciente, el diagnóstico principal, los diagnósticos secundarios (comorbilidad y complicaciones) y los procedimientos realizados son las variables críticas para el ajuste de riesgos. De ahí la importancia de su correcta incorporación al CMBD. Sin embargo, diversos trabajos, especialmente en Estados Unidos, pero también en España, han puesto en evidencia importantes problemas de calidad en estos datos, dificultades para su mejora y las limitaciones que ello conlleva para evaluar la calidad o la eficiencia de los hospitales. El objetivo de este trabajo es realizar una aproximación a la calidad de la información administrativa y clínica recogida en el CMBD del Servei Valencià de la Salut (SVS) mediante un proceso automatizado de análisis de los datos del propio CMBD, y discutir tanto sus implicaciones para la gestión, como las posibles estrategias de mejora.Material y métodoSe realizó un análisis automatizado de la calidad del CMBD 1994 del SVS (20 hospitales, 241.341 altas), utilizando indicadores de cumplimentación válida de los valores de los campos, relaciones entre campos del mismo episodio, relaciones entre variables en diferentes episodios y volumen y especificidad de la información clínica.ResultadosEl CMBD analizado contiene escasos errores en las variables administrativas, con excepción de la residencia, pero presenta importantes problemas de volumen y especificidad de la información clínica, así como una alta variabilidad en su cumplimentación y calidad en diferentes hospitales.ConclusionesLa calidad de los datos clínicos del CMBD pueden suponer sesgos en su utilización con finalidades de gestión o evaluación de la calidad, así como en los estudios epidemiológicos, de evaluación de tecnologías o utilización de servicios.SummarySettingTogether with the age of the patient, the main diagnosis, secondary diagnosis (comorbility and complications) and the procedures performed are the critical variables for risk-adjusting. Therefore, its correct incorporation to CMBD is of great importance. However, several studies, especially in the United States, but also in Spain, have made evident the existence of important problems of quality in these data, difficulties for its improvement and the limitations which this has to assess the quality or the efficiency of hospitals. The objective of this study is to approach the quality of administrative and clinical collected in the CMBD of the Valencian Health Service (VHS) using an automatized process of analysis of data from the same CMBD, and discuss the implications for its management, as well as possible improvement strategies.Material and methodAn automatized analysis of the quality of CMBD 1994 of the VHS (20 hospitals, 241,341 admissions) was performed, using indicators of valid fulfilling of field values, relationship between fields of the same episode, relationship between variables in different episodes and volume and specificity of clinical information.ResultsThe analysed CMBD contains few errors in management variables, with the exception of residence, but it shows important problems of volume and specificity of clinical information, as well as a high variability in its fulfilling and quality in different hospitals.ConclusionsThe quality of the clinical data of CMBD may be biased in its use with management aims or when assessing quality, as well as in epidemiological studies, evaluation of technology or use of services

Wake dynamics of external flow past a curved circular cylinder with the free stream aligned with the plane of curvature

Accepted versio

Efficient vectorised Cuda kernels for high-order finite element flow solvers

In this work, we develop efficient kernels for elemental operators of matrix-free solvers of the Helmholtz equation, which are the core operations for more complete Navier-Stokes solvers. We consider straight-sided and deformed quadrilateral elements from unstructured high-order meshes. We investigate two types of efficient CUDA kernels for a range of polynomial orders; a first type which maps each elemental operation to a CUDA-thread, and a second that maps each element to a CUDA-block. Our results show that the first option is beneficial for small elements with low polynomial order, whereas the second option is beneficial for larger elements. For both options we show the importance of the right layout of data structures, and analyse the effect of utilising different memory spaces on the GPU

An isoparametric approach to high-order curvilinear boundary-layer meshing

This is the final version of the article. Available from Elsevier via the DOI in this record.The generation of high-order curvilinear meshes for complex three-dimensional geometries is presently a challenging topic, particularly for meshes used in simulations at high Reynolds numbers where a thin boundary layer exists near walls and elements are highly stretched in the direction normal to flow. In this paper, we present a conceptually simple but very effective and modular method to address this issue. We propose an isoparametric approach, whereby a mesh containing a valid coarse discretization comprising of high-order triangular prisms near walls is refined to obtain a finer prismatic or tetrahedral boundary-layer mesh. The validity of the prismatic mesh provides a suitable mapping that allows one to obtain very fine mesh resolutions across the thickness of the boundary layer. We describe the method in detail for a high-order approximation using modal basis functions, discuss the requirements for the splitting method to produce valid prismatic and tetrahedral meshes and provide a sufficient criterion of validity in both cases. By considering two complex aeronautical configurations, we demonstrate how highly stretched meshes with sufficient resolution within the laminar sublayer can be generated to enable the simulation of flows with Reynolds numbers of 106 and above.This work was partly supported by EU Grant No. 265780 as part of the EU FP7 project “IDIHOM: Industrialization of High-Order Methods — A Top-Down Approach”. We would like to thank Dr. Tobias Leicht of DLR for asking a very pertinent question concerning the validity of the generated high-order mesh that we believe to have answered in this article. We also thank Jean-Eloi Lombard for his assistance in generating the mesh for Fig. 15

On the eddy-resolving capability of high-order discontinuous Galerkin approaches to implicit LES / under-resolved DNS of Euler turbulence

AbstractWe present estimates of spectral resolution power for under-resolved turbulent Euler flows obtained with high-order discontinuous Galerkin (DG) methods. The ‘1% rule’ based on linear dispersion–diffusion analysis introduced by Moura et al. (2015) [10] is here adapted for 3D energy spectra and validated through the inviscid Taylor–Green vortex problem. The 1% rule estimates the wavenumber beyond which numerical diffusion induces an artificial dissipation range on measured energy spectra. As the original rule relies on standard upwinding, different Riemann solvers are tested. Very good agreement is found for solvers which treat the different physical waves in a consistent manner. Relatively good agreement is still found for simpler solvers. The latter however displayed spurious features attributed to the inconsistent treatment of different physical waves. It is argued that, in the limit of vanishing viscosity, such features might have a significant impact on robustness and solution quality. The estimates proposed are regarded as useful guidelines for no-model DG-based simulations of free turbulence at very high Reynolds numbers

Automatic generation of 3D unstructured high-order curvilinear meshes

This is the final version of the article. Available from the publisher via the DOI in this record.The generation of suitable, good quality high-order meshes is a significant obstacle in the academic and industrial uptake of high-order CFD methods. These methods have a number of favourable characteristics such as low dispersion and dissipation and higher levels of numerical accuracy than their low-order counterparts, however the methods are highly susceptible to inaccuracies caused by low quality meshes. These meshes require significant curvature to accuratly describe the geometric surfaces, which presents a number of difficult challenges in their generation. As yet, research into the field has produced a number of interesting technologies that go some way towards achieving this goal, but are yet to provide a complete system that can systematically produce curved high-order meshes for arbitrary geometries for CFD analysis. This paper presents our efforts in that direction and introduces an open-source high-order mesh generator, NekMesh, which has been created to bring high-order meshing technologies into one coherent pipeline which aims to produce 3D high-order curvilinear meshes from CAD geometries in a robust and systematic way