Persona: Pérez Martín, Jorge
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Pérez Martín
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Jorge
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Publicación Análisis de coste-efectividad en OpenMarkov. Aplicación al implante coclear bilateral pediátrico en España(Universidad Nacional de Educación a Distancia (España). Escuela Técnica Superior de Ingeniería Informática. Departamento de Inteligencia Artificial., 2015-10-05) Pérez Martín, Jorge; Díez Vegas, Francisco JavierEl uso de implantes cocleares es, a día de hoy la terapia más efectiva para el tratamiento de la sordera severa y profunda. Diferentes estudios han demostrado que el implante coclear unilateral es coste-efectivo en niños y en adultos. Investigaciones recientes indican que el implante coclear bilateral (un implante en cada oído) es coste-efectivo en niños, pero el grado de incertidumbre sigue siendo elevado. El objetivo de este estudio consiste en determinar con la mayor precisión posible si el implante coclear bilateral pediátrico es coste-efectivo. Con este fin se ha construido un modelo gráfico probabilista que representa los sucesos que pueden producirse a lo largo de la vida del usuario, su impacto en la calidad de vida y los costes asociados, distinguiendo los costes que cubre el sistema nacional de sanidad de los que en España asumen los usuarios y sus familias. La construcción y la evaluación del modelo se han realizado con la herramienta de software libre OpenMarkov, desarrollada en Centro de Investigación sobre Sistemas Inteligentes de Ayuda a la Decisión (CISIAD) de la UNED, para lo cual se han añadido nuevas funcionalidades y se han extendido algunas de las ya existentes. Varios estudios han estimado que la disposición a pagar (también conocida como “umbral de coste-efectividad”) implícitamente utilizada por el sistema de sanidad español si sitúa entre entre 30.000 y 35.000 € por año de vida ajustado en calidad (AVAC). Según los resultados de nuestro modelo, la razón de coste-efectividad incremental (RCEI) del implante simultáneo frente al unilateral para niños de un año de edad es de 12.133 €/AVAC, lo cual implica que conviene poner dos implantes todos los que los necesitan. El análisis de sensibilidad confirma esta conclusión, pues para un umbral de 30.000 €/AVAC la probabilidad de que esta intervención sea coste-efectivo alcanza el 98 %. Incluso en el caso de que el sistema nacional de salud asumiera los costes que en nuestro país cubren actualmente las familias,la intervención seguiría siendo coste-efectiva, con una RCEI de 17.263 €/AVAC y una probabilidad del 94 %. La implantación debe hacerse de forma simultánea, es decir, en una sola operación quirúrgica, porque la implantación secuencial tiene la misma efectividad pero mayor coste para el sistema sanitario y para la familia. Nuestro modelo no es capaz de estimar la RCEI para niños mayores de un año porque la efectividad depende de muchos factores, principalmente de la edad actual, cuándo apareció la sordera, cuándo fue diagnosticada y, en su caso, cuándo se realizó el primer implante. Este modelo estará disponible públicamente para que otros investigadores puedan reproducir los resultados y adaptarlo a otros contextos. En particular, sería interesante analizar la RCEI en adultos y en otros países.Publicación Deep Learning for Describing Breast Ultrasound Images with BI-RADS Terms(Springer, 2024) Carrilero Mardones, Mikel; Parras Jurado, Manuela; Nogales, Alberto; Pérez Martín, Jorge; Díez Vegas, Francisco Javier; https://orcid.org/0000-0003-4951-8102Breast cancer is the most common cancer in women. Ultrasound is one of the most used techniques for diagnosis, but an expert in the field is necessary to interpret the test. Computer-aided diagnosis (CAD) systems aim to help physicians during this process. Experts use the Breast Imaging-Reporting and Data System (BI-RADS) to describe tumors according to several features (shape, margin, orientation...) and estimate their malignancy, with a common language. To aid in tumor diagnosis with BI-RADS explanations, this paper presents a deep neural network for tumor detection, description, and classification. An expert radiologist described with BI-RADS terms 749 nodules taken from public datasets. The YOLO detection algorithm is used to obtain Regions of Interest (ROIs), and then a model, based on a multi-class classification architecture, receives as input each ROI and outputs the BI-RADS descriptors, the BI-RADS classification (with 6 categories), and a Boolean classification of malignancy. Six hundred of the nodules were used for 10-fold cross-validation (CV) and 149 for testing. The accuracy of this model was compared with state-of-the-art CNNs for the same task. This model outperforms plain classifiers in the agreement with the expert (Cohen’s kappa), with a mean over the descriptors of 0.58 in CV and 0.64 in testing, while the second best model yielded kappas of 0.55 and 0.59, respectively. Adding YOLO to the model significantly enhances the performance (0.16 in CV and 0.09 in testing). More importantly, training the model with BI-RADS descriptors enables the explainability of the Boolean malignancy classification without reducing accuracy.Publicación Assessment of Video Accessibility by Students of a MOOC on Digital Materials for All(Institute of Electrical and Electronics Engineers, 2021-05-21) Elisa M. Molanes López; Rodríguez Ascaso, Alejandro; Letón Molina, Emilio; Pérez Martín, Jorge; https://orcid.org/0000-0003-3217-8551The assessment of multimedia accessibility is a relevant, complex and time-consuming task, which takes more than simply checking whether the video has audiodescription and captions or not. In our study, we face this challenge through the: 1) involvement of a cohort of novice evaluators, who previously took part in a MOOC on the accessibility of digital content and 2) the division of the accessibility assessment into the application of a set of criteria. Two groups of novice accessibility testers were asked to evaluate the accessibility of two similar videos, one video per group. While both videos were equivalent in terms of their pedagogical content, only one of them had non-severe accessibility barriers for people with low vision and for blind people. Each participant was asked to rate qualitatively a set of statements extracted from the WCAG 2.1 success criteria, one generic statement about the video accessibility, and a set of statements on the quality perception and the aspects of personal preference. The largest differences in ratings occurred for statements whose success criteria had been improved. It was also the case for one success criterion that is understandable but hardly applicable by novice evaluators, according to the literature. However, the difference was statistically significant only for the success criterion with more salient differences between both videos. As a main conclusion, a group of novice evaluators can identify accessibility problems in videos when using specific accessibility statements.Publicación Cost-effectiveness of Pediatric Bilateral Cochlear Implantation in Spain(Wiley Online Library, 2017) Artaso, Miguel A.; Díez Vegas, Francisco Javier; Pérez Martín, JorgeObjective: To determine the incremental cost-effectiveness of bilateral versus unilateral cochlear implantation for one-year-old children suffering from bilateral sensorineural severe to profound hearing loss from the perspective of the Spanish public health system. Study Design: Cost-utility analysis. Methods: We conducted a general-population survey to estimate the quality of life increase contributed by the second implant. We built a Markov influence diagram and evaluated it for a life-long time horizon with a 3% discount rate in the base case. Results: The incremental cost-effectiveness ratio (ICER) of simultaneous bilateral implantation with respect to unilateral implantation for one-year-old children with severe to profound deafness is €10,323 per quality-adjusted life year (QALY). For sequential bilateral implantation, it rises to €11,733/QALY. Both options are cost-effective for the Spanish health system, whose willingness to pay is estimated at around €30,000/QALY. The probabilistic sensitivity analysis shows that the probability of bilateral implantation being cost-effective reaches 100% for that cost-effectiveness threshold. Conclusions: Bilateral implantation is clearly cost-effective for the population considered. If possible, it should be done simultaneously, i.e., in one surgical operation, because it is as safe and effective as sequential implantation, and saves costs for the system and for users and their families. Sequential implantation is also cost-effective for children who have received the first implant recently, but it is difficult to determine when it ceases to be so because of the lack of detailed data. These results are specific for Spain but the model can easily be adapted to other countries. Level of Evidence: 2CPublicación La infraestructura de la calidad para apoyar la contratación pública sostenible(2024) Massó Aguado, Daniel; Arbeloa Losada, Marta; García López, Paloma; Pérez Martín, JorgePublicación Markov influence diagrams: a graphical tool for cost-effectiveness analysis(Society for Medical Decision Making, 2017-01-11) Yebra, Mar; Bermejo, Iñigo; Palacios Alonso, Miguel Ángel; Arias Calleja, Manuel; Luque Gallego, Manuel; Pérez Martín, Jorge; Díez Vegas, Francisco JavierMarkov influence diagrams (MIDs) are a new type of probabilistic graphical models that extend influence diagrams in the same way as Markov decision trees extend decision trees. They have been designed to build state-transition models, mainly in medicine, and perform cost-effectiveness analysis. Using a causal graph that may contain several variables per cycle, MIDs can model various features of the patient without multiplying the number of states; in particular, they can represent the history of the patient without using tunnel states. OpenMarkov, an open-source tool, allows the decision analyst to build and evaluate MIDs—including cost-effectiveness analysis and several types of deterministic and probabilistic sensitivity analysis—with a graphical user interface, without writing any code. This way, MIDs can be used to easily build and evaluate complex models whose implementation as spreadsheets or decision trees would be cumbersome or unfeasible in practice. Furthermore, many problems that previously required discrete event simulation can be solved with MIDs, i.e., within the paradigm of state-transition models, in which many health economists feel more comfortable.Publicación El papel de los consumidores para alcanzar los ODS(2024) Massó Aguado, Daniel; Arbeloa Losada, Marta; García López, Paloma; Pérez Martín, JorgePublicación Performance of students with different accessibility needs and preferences in “Design for All” MOOCs(Public Library of Science, 2024-03-07) Rodríguez Ascaso, Alejandro; Molanes López, Elisa M.; Jorge Pe´rez-Martı´nI; Pérez Martín, Jorge; Letón Molina, Emilio; https://orcid.org/0000-0003-3217-8551Recent research has shown that Massive Open Online Courses (MOOCs) create barriers for students with disabilities. Not taking into account their needs in the design, production or delivery of MOOCs may be one of the main causes behind this. It leads to poor compliance with suitable learning designs and web accessibility standards, as well as a lack of knowledge about the students’ needs. The objective of our research is to analyze the learning performance of the students in MOOCs on topics related to Design for All, offered in an Open edX-based platform. Accessibility support was conceived from the outset, including compliance of both the platform and the learning resources with the WCAG 2.1 accessibility standard, and with a subset of the principles of Universal Design for Learning. Additionally, students were consulted on their accessibility needs and preferences, following publicly available modeling schemes and previous research. From a sample of 765 students, who completed at least one of the graded assessment activities of the course, a multilevel multiple logistic regression model was fitted. Based on that model, the results indicate that: a) users of screen readers and users of captions show a statistically significant positive association with a good performance when compared to students with no preferences, with an odds ratio of, respectively, OR = 13.482 and OR = 13.701; b) students who have low vision or very low vision show a significant negative association with a good performance when compared to users of screen readers and to users of captions, with OR = 26.817 and OR = 27.254, respectively.Publicación Quality analysis of a breast thermal images database(Sage Journals, 2023-02-02) Sánchez Cauce, Raquel; Pérez Martín, Jorge; https://orcid.org/0000-0002-1128-3988The study and early detection of breast cancer are key for its treatment. We carry out an exhaustive analysis of the most used database for mastology research with infrared images, analyzing the anomalies according to five quality dimensions: completeness, correctness, concordance, plausibility, and currency. We established control queries that looked for these anomalies and that can be used to ensure the quality of the database. Finally, we briefly review the more than 40 papers that use this database and that do not mention any of these anomalies. When analyzing the database, we found 365 anomalies related to personal and clinical data, and thermal images. The errors found in our research may lead to a modification of the results and conclusions made in the articles found in the literature, serve as a basis for improvements in the quality of the database, and help future researchers to work with it.Publicación Teaching Probabilistic Graphical Models with OpenMarkov(MDPI, 2022-11-30) Díez Vegas, Francisco Javier; Arias Calleja, Manuel; Pérez Martín, Jorge; Luque Gallego, ManuelOpenMarkov is an open-source software tool for probabilistic graphical models. It has been developed especially for medicine, but has also been used to build applications in other fields and for tuition, in more than 30 countries. In this paper we explain how to use it as a pedagogical tool to teach the main concepts of Bayesian networks and influence diagrams, such as conditional dependence and independence, d-separation, Markov blankets, explaining away, optimal policies, expected utilities, etc., and some inference algorithms: logic sampling, likelihood weighting, and arc reversal. The facilities for learning Bayesian networks interactively can be used to illustrate step by step the performance of the two basic algorithms: search-and-score and PC.