FORT: una herramienta de regresión borrosa

El uso de las técnicas de regresión sobre las observaciones experimentales ha permitido el estudio de numerosos fenómenos en diversos campos de la ciencia, y muy especialmente en las ciencias sociales. Dichas técnicas requieren de un número suficiente de observaciones “precisas”, exactas y fiables. Sin embargo, no siempre es posible obtener el conjunto de observaciones necesario, o éstas contienen algún tipo de imperfección en los datos, debido a la imprecisión o vaguedad de los mismos. En cualquier caso, con suficientes datos o no, con imperfecciones o no, los modelos obtenidos deberían proveer de capacidades predictivas y descriptivas [JCr02]. Las actuales herramientas, o las más fácilmente accesibles, tienen limitado el uso de modelos y difícilmente usan las técnicas de la teoría de conjuntos borrosos. Se propone en este trabajo una herramienta abierta de regresión que admita el uso de cualquier modelo de curva independientemente de su naturaleza. Además, esta herramienta permitirá el uso de diferentes formas de borrosidad y por su diseño permitiría cualquier modelo propuesto por el usuario si éste prevee que éstos tienen características que sean suficientemente predictivas y descriptivas. Esta primera aproximación de una herramienta abierta de regresión se realiza un estudio sobre diferentes modelos paramétricos simbólicos, usados comúnmente en la práctica en disciplinas tan heterogéneas como pueden ser la Ingeniería del Software, la Economía o en cualquier campo en donde puedan aparecer imprecisiones en la información. [ABSTRACT] The use of regression techniques in experimental observations has led to the study of numerous phenomena in various fields of science, especially in social science. These techniques require a sufficient number of “precise”, exact and reliable observations. However, it is not always possible to obtain all the necessary group of observations or these have some failings, as a result of inexact or vague data. Nevertheless, having more or less data, with or without failings, the obtained paradigms should provide predictive and descriptive capacities. The current tools or those more accessible have limited paradigm application and hardly use the techniques relating the fuzzy sets theory. In this first approach to an open regression tool, a study has been carried out of the different parametric, symbolic paradigms, commonly used in the practice of such diverse disciplines as Software Engineering, Economy or any other field where information imprecision can appear

The evolution of the ventilatory ratio is a prognostic factor in mechanically ventilated COVID-19 ARDS patients

Background: Mortality due to COVID-19 is high, especially in patients requiring mechanical ventilation. The purpose of the study is to investigate associations between mortality and variables measured during the first three days of mechanical ventilation in patients with COVID-19 intubated at ICU admission. Methods: Multicenter, observational, cohort study includes consecutive patients with COVID-19 admitted to 44 Spanish ICUs between February 25 and July 31, 2020, who required intubation at ICU admission and mechanical ventilation for more than three days. We collected demographic and clinical data prior to admission; information about clinical evolution at days 1 and 3 of mechanical ventilation; and outcomes. Results: Of the 2,095 patients with COVID-19 admitted to the ICU, 1,118 (53.3%) were intubated at day 1 and remained under mechanical ventilation at day three. From days 1 to 3, PaO2/FiO2 increased from 115.6 [80.0-171.2] to 180.0 [135.4-227.9] mmHg and the ventilatory ratio from 1.73 [1.33-2.25] to 1.96 [1.61-2.40]. In-hospital mortality was 38.7%. A higher increase between ICU admission and day 3 in the ventilatory ratio (OR 1.04 [CI 1.01-1.07], p = 0.030) and creatinine levels (OR 1.05 [CI 1.01-1.09], p = 0.005) and a lower increase in platelet counts (OR 0.96 [CI 0.93-1.00], p = 0.037) were independently associated with a higher risk of death. No association between mortality and the PaO2/FiO2 variation was observed (OR 0.99 [CI 0.95 to 1.02], p = 0.47). Conclusions: Higher ventilatory ratio and its increase at day 3 is associated with mortality in patients with COVID-19 receiving mechanical ventilation at ICU admission. No association was found in the PaO2/FiO2 variation