Mortality prediction of septic shock patients using probabilistic fuzzy systems

Mortality scores based on multiple regressions are common in critical care medicine for prognostic stratification of patients. However, to be used at the point of care, they need to be both accurate and easily interpretable. In this work, we propose the application of one existent type of rule base system using statistical information – probabilistic fuzzy systems (PFS) – to predict mortality of septic shock patients. To assess its accuracy and interpretability, these models are compared to methodologies previously proposed in this domain: Takagi-Sugeno fuzzy models and logistic regression models. The methods are tested using a retrospective cohort study including ICU patients with abdominal septic shock. Regarding accuracy, PFS models are comparable to fuzzy modeling and logistic regression. In terms of interpretability, results indicate that PFS models increase the transparency of the learned system (using fuzzy rules), but at the same time, provide additional means for validating the fuzzy classifier using expert knowledge (from physicians in this paper). By providing accurate and interpretable estimates for the mortality risk, results suggest the usefulness of PFS to develop scores for critical care medicine

Mortality prediction of septic shock patients using probabilistic fuzzy systems

Mortality scores based on multiple regressions are common in critical care medicine for prognostic stratification of patients. However, to be used at the point of care, they need to be both accurate and easily interpretable. In this work, we propose the application of one existent type of rule base system using statistical information – probabilistic fuzzy systems (PFS) – to predict mortality of septic shock patients. To assess its accuracy and interpretability, these models are compared to methodologies previously proposed in this domain: Takagi-Sugeno fuzzy models and logistic regression models. The methods are tested using a retrospective cohort study including ICU patients with abdominal septic shock. Regarding accuracy, PFS models are comparable to fuzzy modeling and logistic regression. In terms of interpretability, results indicate that PFS models increase the transparency of the learned system (using fuzzy rules), but at the same time, provide additional means for validating the fuzzy classifier using expert knowledge (from physicians in this paper). By providing accurate and interpretable estimates for the mortality risk, results suggest the usefulness of PFS to develop scores for critical care medicine

Probabilistic fuzzy prediction of mortality in intensive care units

In the present work, we propose the application of probabilistic fuzzy systems (PFS) to model the prediction of mortality in septic shock patients. This technique is characterized by the combination of the linguistic description of the system with the statistical properties of data. Preliminary results for this particular clinical problem point that PFS models, besides performing as accurately as first order Takagi-Sugeno fuzzy models, also provide probability measures that provide additional clinical information upon which physicians can act on

Predicting septic shock outcomes in a database with missing data using fuzzy modeling : influence of pre-processing techniques on real world data-based classification

Real-world databases often contain missing data and existing correction algorithms deliver varying performance. Also, most modeling techniques are not suitable to deal with them automatically. In this study we examine different approaches to predicting septic shock in the presence of missing data. Some preprocessing techniques for managing missing data include disregarding data, or replacing it with information that by design introduces bias. In this study, we show that predictive performance improves by employing a minimum pre-processing technique, the Zero-Order-Hold (ZOH) method, by applying a Fuzzy C-Means clustering technique based on the partial distance calculation strategy (FCM-PDS) and by computing the final classification regarding the samples from each patient. Performance improvements continue to occur where up to approximately 60% of the data is missing, though for higher percentage the classification performance still is statistically improved. We further validate this approach by making comparisons with previous studies

Rabbits (Oryctolagus cuniculus) as experimental hosts for Amblyomma dubitatum Neumann (Acari: Ixodidae) Coelhos (Oryctolagus cuniculus) como hospedeiros experimentais de Amblyomma dubitatum Neumann (Acari: Ixodidae)

<abstract language="por">O ciclo biológico do Amblyomma dubitatum, que se alimentava experimentalmente em coelhos domésticos, foi avaliado em condições laboratoriais e comparado com dados recentemente obtidos de infestações experimentais em capivaras (Hydrochaeris hydrochaeris), hospedeiros naturais para essa espécie. Os coelhos foram considerados hospedeiros experimentais adequados para larvas e ninfas porque quatro dos cinco parâmetros avaliados (número de carrapatos que ingurgitaram, período de alimentação, percentagem de carrapatos que realizaram muda e período de pré-muda) foram semelhantes aos resultados obtidos com capivaras. As percentagens diárias de desprendimento e de muda das larvas e ninfas confirmam os coelhos como hospedeiros experimentais adequados para esses estágios de A. dubitatum. Os resultados do experimento indicam que os coelhos são hospedeiros inadequados para os adultos

Life cycle of female ticks of Amblyomma cooperi Nuttal & Warburton, 1908 (Acari: Ixodidae) under laboratory conditions Ciclo biológico de fêmeas do carrapato Amblyomma cooperi Nuttal & Warburton, 1908 (Acari:Ixodidae) sob condições de laboratório

The biological cycle of female ticks of Amblyomma cooperi was studied under controlled conditions. The study has begun with two engorged females collected in a naturally infested wild capybara. The larvae originated from the oviposition of these two females were used for collecting young adults through artificial infestations in rabbits. The female parasitic and free living phases were evaluated using artificial infestation of ticks in a capybara. The average body weight of females was 958.2± 175.6mg, the average pre-egg laying period was 8.5± 1.4 days, the reproductive efficiency index was 59.5± 4.2 and the nutritional efficiency index was 77.3± 4.8. The incubation and eclosion periods were 41.9 and 5.9 days, respectively, and the rate of eclosion was 64%. These figures were obtained under high relative humidity conditions which were necessary for the success of the egg incubation process of this species. The preliminary data obtained with the artificial infestation in rabbits raises the possibility of this and other domestic species be used as an epidemiologic link between the domestic and the wild environment with the potential exposure of human populations to A. cooperi and to the maculosa fever agent.<br>O ciclo biológico de Amblyomma cooperi foi estudado sob condições de laboratório. O estudo iniciou-se com duas fêmeas ingurgitadas coletadas de uma capivara selvagem naturalmente infestada. As larvas provenientes da postura foram utilizadas para obtenção de adultos, por meio de infestação artificial em coelhos. As fases parasitária e de vida livre das fêmeas foram avaliadas utilizando-se infestação artificial em capivara. A média de peso corporal foi de 958,2± 175,6mg, a média do período de pré-postura de 8,5± 1,4 dias e dos índices de eficiência reprodutiva e nutricional de 59,5± 4,2 e 77,3± 4,6, respectivamente. Os períodos de incubação e eclosão foram de 41,9 e 5,9 dias, respectivamente. A taxa de eclosão foi de 64%. Estes dados foram obtidos sob alta umidade relativa, necessária para o sucesso da incubação dos ovos dessa espécie. Os dados preliminares obtidos com a infestação artificial em coelhos levanta a possibilidade dessa e de outras espécies domésticas serem possíveis elos epidemiológicos entre o ambiente doméstico e o silvestre, com potencial risco de exposição humana a A. cooperi e ao agente etiológico da febre maculosa