Framework for Skew-Probit Links in Binary Regression

We review several asymmetrical links for binary regression models and present a unified approach for two skew-probit links proposed in the literature. Moreover, under skew-probit link, conditions for the existence of the ML estimators and the posterior distribution under improper priors are established. The framework proposed here considers two sets of latent variables which are helpful to implement the Bayesian MCMC approach. A simulation study to criteria for models comparison is conducted and two applications are made. Using different Bayesian criteria we show that, for these data sets, the skew-probit links are better than alternative links proposed in the literature.

Bayesian binary regression model: an application to in-hospital death after AMI prediction

Um modelo bayesiano de regressão binária é desenvolvido para predizer óbito hospitalar em pacientes acometidos por infarto agudo do miocárdio. Métodos de Monte Carlo via Cadeias de Markov (MCMC) são usados para fazer inferência e validação. Uma estratégia para construção de modelos, baseada no uso do fator de Bayes, é proposta e aspectos de validação são extensivamente discutidos neste artigo, incluindo a distribuição a posteriori para o índice de concordância e análise de resíduos. A determinação de fatores de risco, baseados em variáveis disponíveis na chegada do paciente ao hospital, é muito importante para a tomada de decisão sobre o curso do tratamento. O modelo identificado se revela fortemente confiável e acurado, com uma taxa de classificação correta de 88% e um índice de concordância de 83%.

Bayesian outlier analysis in binary regression

We propose alternative approaches to analyze residuals in binary regression models based on random effect components. Our preferred model does not depend upon any tuning parameter, being completely automatic. Although the focus is mainly on accommodation of outliers, the proposed methodology is also able to detect them. Our approach consists of evaluating the posterior distribution of random effects included in the linear predictor. The evaluation of the posterior distributions of interest involves cumbersome integration, which is easily dealt with through stochastic simulation methods. We also discuss different specifications of prior distributions for the random effects. The potential of these strategies is compared in a real data set. The main finding is that the inclusion of extra variability accommodates the outliers, improving the adjustment of the model substantially, besides correctly indicating the possible outliers.

Latent residual analysis in binary regression with skewed link

Model diagnostics is an integral part of model determination and an important part of the model diagnostics is residual analysis. We adapt and implement residuals considered in the literature for the probit, logistic and skew-probit links under binary regression. New latent residuals for the skew-probit link are proposed here. We have detected the presence of outliers using the residuals proposed here for different models in a simulated dataset and a real medical dataset.

Effects Of Therapeutic Approach On The Neonatal Evolution Of Very Low Birth Weight Infants With Patent Ductus Arteriosus.

To analyze the effects of treatment approach on the outcomes of newborns (birth weight [BW] < 1,000 g) with patent ductus arteriosus (PDA), from the Brazilian Neonatal Research Network (BNRN) on: death, bronchopulmonary dysplasia (BPD), severe intraventricular hemorrhage (IVH III/IV), retinopathy of prematurity requiring surgical (ROPsur), necrotizing enterocolitis requiring surgery (NECsur), and death/BPD. This was a multicentric, cohort study, retrospective data collection, including newborns (BW < 1000 g) with gestational age (GA) < 33 weeks and echocardiographic diagnosis of PDA, from 16 neonatal units of the BNRN from January 1, 2010 to Dec 31, 2011. Newborns who died or were transferred until the third day of life, and those with presence of congenital malformation or infection were excluded. Groups: G1 - conservative approach (without treatment), G2 - pharmacologic (indomethacin or ibuprofen), G3 - surgical ligation (independent of previous treatment). Factors analyzed: antenatal corticosteroid, cesarean section, BW, GA, 5 min. Apgar score < 4, male gender, Score for Neonatal Acute Physiology Perinatal Extension (SNAPPE II), respiratory distress syndrome (RDS), late sepsis (LS), mechanical ventilation (MV), surfactant (< 2 h of life), and time of MV. death, O2 dependence at 36 weeks (BPD36wks), IVH III/IV, ROPsur, NECsur, and death/BPD36wks. Student's t-test, chi-squared test, or Fisher's exact test; Odds ratio (95% CI); logistic binary regression and backward stepwise multiple regression. Software: MedCalc (Medical Calculator) software, version 12.1.4.0. p-values < 0.05 were considered statistically significant. 1,097 newborns were selected and 494 newborns were included: G1 - 187 (37.8%), G2 - 205 (41.5%), and G3 - 102 (20.6%). The highest mortality was observed in G1 (51.3%) and the lowest in G3 (14.7%). The highest frequencies of BPD36wks (70.6%) and ROPsur were observed in G3 (23.5%). The lowest occurrence of death/BPD36wks occurred in G2 (58.0%). Pharmacological (OR 0.29; 95% CI: 0.14-0.62) and conservative (OR 0.34; 95% CI: 0.14-0.79) treatments were protective for the outcome death/BPD36wks. The conservative approach of PDA was associated to high mortality, the surgical approach to the occurrence of BPD36wks and ROPsur, and the pharmacological treatment was protective for the outcome death/BPD36wks.

Lateral Pterygoid Muscle Volume And Migraine In Patients With Temporomandibular Disorders.

Lateral pterygoid muscle (LPM) plays an important role in jaw movement and has been implicated in Temporomandibular disorders (TMDs). Migraine has been described as a common symptom in patients with TMDs and may be related to muscle hyperactivity. This study aimed to compare LPM volume in individuals with and without migraine, using segmentation of the LPM in magnetic resonance (MR) imaging of the TMJ. Twenty patients with migraine and 20 volunteers without migraine underwent a clinical examination of the TMJ, according to the Research Diagnostic Criteria for TMDs. MR imaging was performed and the LPM was segmented using the ITK-SNAP 1.4.1 software, which calculates the volume of each segmented structure in voxels per cubic millimeter. The chi-squared test and the Fisher's exact test were used to relate the TMD variables obtained from the MR images and clinical examinations to the presence of migraine. Logistic binary regression was used to determine the importance of each factor for predicting the presence of a migraine headache. Patients with TMDs and migraine tended to have hypertrophy of the LPM (58.7%). In addition, abnormal mandibular movements (61.2%) and disc displacement (70.0%) were found to be the most common signs in patients with TMDs and migraine. In patients with TMDs and simultaneous migraine, the LPM tends to be hypertrophic. LPM segmentation on MR imaging may be an alternative method to study this muscle in such patients because the hypertrophic LPM is not always palpable.

Orthotopic Liver Transplantation in Familial Amyloidotic Polyneuropathy Is Associated with Long-Term Progression of Renal Disease

Orthotopic liver transplantation has become the treatment of choice for familial amyloidotic polyneuropathy. The aims of this study were to evaluate the renal complications post orthotopic liver transplantation in familial amyloidotic polyneuropathy and their impact. We retrospectively studied 185 recipients who underwent 217 orthotopic liver transplants. Mean age 36.8±9.5 years, 59% males, 14.3% with renal dysfunction pre orthotopic liver transplantation. Mean follow-up 3.6±3.7 years. Thirty-two patients died. Univariate and multivariate analysis were performed, and p<0.05 was considered significant. Acute kidney injury occurred in 57 patients and renal replacement therapy was needed in 16/57. In multivariate analysis, acute kidney injury was correlated with development of chronic kidney disease (p<0.001). Relating to development of chronic kidney disease, 23.5% had progress to stage 3, 6% to stage 4 and 5.1% to stage 5d. According to Spearmen correlation, risk factors for chronic kidney disease development were age (p<0.001), renal dysfunction pre orthotopic liver transplantation (p<0.001) and acute kidney injury post orthotopic liver transplantation (p<0.001). Mortality was correlated with age (p<0.001), retransplantation need (p=0.004), renal dysfunction pre orthotopic liver transplantation (p<0.001), acute kidney injury post orthotopic liver transplantation (p=0.04), and chronic kidney disease stage 5 (p<0.001). Using binary regression, mortality was correlated with chronic kidney disease development (p=0.02). In conclusion, familial amyloidotic polyneuropathy patients are disposed to renal complications that have a negative impact on the survival of these patients.

Fatores de risco auto reportados associados aos acidentes rodoviários : um estudo sobre os condutores portugueses de veículos ligeiros

RESUMO - Objetivos: Anualmente morrem cerca de 1,3 milhões de pessoas, a nível mundial, devido aos acidentes de viação. Também mais de 20 milhões de pessoas sofrem ferimentos ligeiros ou graves devido aos acidentes de viação que resultam em incapacidade temporária ou permanente. Desta forma, consideram-se os acidentes de viação, um grave problema de saúde pública, com custos elevados para as sociedades afetando a saúde das populações e economias de cada país. Este estudo pretendeu descrever e caracterizar os condutores de veículos ligeiros, residentes em Portugal Continental, abrangendo características sociodemográficas, experiência de condução e questões relativas a atitudes, opiniões e comportamentos. Por outro lado procurou-se analisar a associação entre as opiniões, atitudes e comportamentos, auto reportados e a ocorrência de um acidente de viação nos últimos três anos a fim de construir um modelo final preditivo do risco de sofrer um acidente de viação. Método: Foi realizado um estudo observacional analítico transversal baseado num questionário traduzido para a língua portuguesa e com origem no projeto europeu SARTRE 4. A população-alvo foram todos os condutores de veículos ligeiros possuidores de uma licença de condução e residentes em Portugal Continental, baseado numa amostra de igual dimensão à definida no estudo europeu SARTRE 4 (600 condutores de veículos ligeiros). Das 52 perguntas existentes, selecionaram-se pela análise de componentes principais (ACP) variáveis potencialmente independentes e complementares para as componentes opiniões, atitudes e comportamentos. Para além das medidas descritivas usuais, recorreu-se à regressão logística binária para analisar associações e obter um modelo que permitisse estimar a probabilidade de sofrer um acidente rodoviário em função das variáveis selecionadas referentes às opiniões, atitudes e comportamentos auto reportados. Resultados: Dos 612 condutores inquiridos, 62,7% (383) responderam não ter sofrido nenhum acidente de viação nos últimos três anos enquanto 37,3% (228) respondeu ter estado envolvido em pelo menos um acidente de viação com danos materiais ou feridos, no mesmo período. De uma forma geral, o típico condutor que referiu ter sofrido um acidente nos últimos três anos é homem com mais de 65 anos de idade, com o 1º ensino básico, viúvo e sem filhos, não empregado e reside numa área urbana. Os condutores residentes numa área suburbana apresentaram um risco 5,368 mais elevado de sofrer um acidente de viação em relação aos condutores que habitam numa zona rural (IC 95%: 2,344-12,297; p<0,001). Os condutores que foram apenas submetidos uma vez a um controlo de álcool, nos últimos três anos, durante o exercício da condução apresentaram um risco 3,009 superior de sofrer um acidente de viação em relação aos condutores que nunca foram fiscalizados pela polícia (IC 95%: 1,949-4,647, p<0,001). Os condutores que referiram muito frequentemente parar para dormir quando se sentem cansados a conduzir têm uma probabilidade inferior de 81% de sofrer um acidente de viação em relação aos condutores que nunca o fazem (IC 95%: 0,058-0,620; p=0,006). Os condutores que quando cansados raramente bebem um café/bebida energética têm um risco de 4,829 superior de sofrer um acidente de viação do que os condutores que sempre o referiram fazer (IC 95%:1,807-12,903; p=0,002). Conclusões: Os resultados obtidos em relação aos fatores comportamentais vão ao encontro da maioria dos fatores de risco associados aos acidentes de viação referidos na literatura. Ainda assim, foram identificadas novas associações entre o risco de sofrer um acidente e as opiniões e as atitudes auto reportadas que através de estudos de maiores dimensões populacionais poderão vir a ser mais exploradas. Este trabalho vem reforçar a necessidade urgente de novas estratégias de intervenção, principalmente na componente comportamental, direcionadas aos grupos de risco, mantendo as existentes.

Relación entre la presencia de tiroiditis linfocítica con la gravedad y recurrencia/persistencia del carcinoma diferenciado de tiroides.

Introducción: Para el sistema endocrino la neoplasia más frecuente es el cáncer diferenciado de tiroides, con un claro incremento en su incidencia. Es importante encontrar asociaciones que posteriormente permitan establecer factores de riesgo y/o protectores claves en la estrategia terapéutica futura. Por lo que se investigó la relación entre la presencia de tiroiditis linfocítica con la gravedad y persistencia/recurrencia del carcinoma diferenciado de tiroides Materiales y métodos: se hizo un estudio de casos y controles de pacientes con carcinoma diferenciado de tiroides llevados a cirugía entre enero de 1997 y diciembre de 2012 en la Fundación Cardioinfantil, Bogotá, Colombia. Se evaluó la asociación entre la presencia de factores histopatológicos y la presencia de persistencia/recurrencia usando pruebas chi cuadrado y el OR. Para evaluar la presencia de asociación a nivel multivariado se utilizaron modelos de regresión binaria con enlace log log complementario. Resultados: la tiroiditis linfocítica no se asocia con la presencia de ninguna variable de severidad histopatológica. Sin embargo, la tiroiditis linfocítica se asoció con persistencia/recurrencia en presencia invasión vascular (OR 6.6 IC95% 1.4-32), invasión linfática (OR 5.4 IC95% 1.3-22.1), invasión de tejido peritiroideo (OR 1.0-12.3), vaciamiento central positivo (OR 5.1 IC 95% 1.0-2.6) y el, vaciamiento lateral positivo (OR 11.5 IC95% 1.0-12). Con un OR inclusive mayor respecto del grupo sin tiroiditis linfocítica en presencia de invasión linfática (OR 5.4 IC95% 1.3-22 vs 2.6 IC95% 1.2-5.6) y compromiso ganglionar en el vaciamiento lateral (OR 58 IC95% 7.1-476) independiente de la edad y el sexo. Conclusión: la tiroiditis linfocítica no se relaciona con marcadores de severidad histopatológica pero sí con mayor persistencia/recurrencia de la enfermedad.

Bayesian Estimation of the Logistic Positive Exponent IRT Model

A Bayesian inference approach using Markov Chain Monte Carlo (MCMC) is developed for the logistic positive exponent (LPE) model proposed by Samejima and for a new skewed Logistic Item Response Theory (IRT) model, named Reflection LPE model. Both models lead to asymmetric item characteristic curves (ICC) and can be appropriate because a symmetric ICC treats both correct and incorrect answers symmetrically, which results in a logical contradiction in ordering examinees on the ability scale. A data set corresponding to a mathematical test applied in Peruvian public schools is analyzed, where comparisons with other parametric IRT models also are conducted. Several model comparison criteria are discussed and implemented. The main conclusion is that the LPE and RLPE IRT models are easy to implement and seem to provide the best fit to the data set considered.

A Bayesian Semiparametric Approach for Solving the Discrete Calibration Problem

In this article, we introduce a semi-parametric Bayesian approach based on Dirichlet process priors for the discrete calibration problem in binomial regression models. An interesting topic is the dosimetry problem related to the dose-response model. A hierarchical formulation is provided so that a Markov chain Monte Carlo approach is developed. The methodology is applied to simulated and real data.

Saúde física e emocional de cuidadores da cidade de Santa Cruz-RN: perfil epidemiológico e fatores associados

Taking care for an impaired elderly is a hard and costly task that could affect directly the caregiver health. The purpose of this study was to evaluate the physical and mental health of elderly caregivers from the city of Santa Cruz-RN and analyze the potential correlated factors through an observational analytic design of a crosssectional. A multidimensional questionnaire was used to evaluation of the social demographics characteristics and those related to the care activity, as well as the caregivers´ physical and mental health. It was realized a descriptive analyze using frequency distribution and measures of the central tendency and dispersion to description of the caregivers. To verify the magnitude of the association between the variables was used the bivariate analysis through the Pearson and Spearman correlations and qui-square test. To evaluation of the association of the correlated factors to the adverse outcome with the caregivers´ physical and mental health was made a multivariate analysis by logistic binary regression and multiple linear regression models. The final sample was constituted by 304 persons, mostly women with a mean age of 50.3 ±16.8 years. The principal factors related to the physical health were age, stress and life satisfaction. Be a male caregiver, caring for a little while the elderly with cognitive deficit and not been spouse were related to worse mental health. Have worse physical health, high stress, depressive symptomatology, burden and low levels of satisfaction were also related to the mental health. After adjust through multiple linear regression was observed R2 values of R2=0,21 for Stress, R2 =0,17 for Depressive Symptomatology, R2 =0,21 for Burden and R2 =0,16 for Satisfaction. The attainment of the factors associated with caregiver´s health can help in the elaboration of specifics politics witch the goal is the integral attention to the elderly and his caregiver. The inability of continuous taking care could result in adverse outcomes such as institutionalization, impairment and death

Effects of therapeutic approach on the neonatal evolution of very low birth weight infants with patent ductus arteriosus

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Lateral pterygoid muscle volume and migraine in patients with temporomandibular disorders

Lateral pterygoid muscle (LPM) plays an important role in jaw movement and has been implicated in Temporomandibular disorders (TMDs). Migraine has been described as a common symptom in patients with TMDs and may be related to muscle hyperactivity. This study aimed to compare LPM volume in individuals with and without migraine, using segmentation of the LPM in magnetic resonance (MR) imaging of the TMJ. Twenty patients with migraine and 20 volunteers without migraine underwent a clinical examination of the TMJ, according to the Research Diagnostic Criteria for TMDs. MR imaging was performed and the LPM was segmented using the ITK-SNAP 1.4.1 software, which calculates the volume of each segmented structure in voxels per cubic millimeter. The chi-squared test and the Fisher's exact test were used to relate the TMD variables obtained from the MR images and clinical examinations to the presence of migraine. Logistic binary regression was used to determine the importance of each factor for predicting the presence of a migraine headache. Patients with TMDs and migraine tended to have hypertrophy of the LPM (58.7%). In addition, abnormal mandibular movements (61.2%) and disc displacement (70.0%) were found to be the most common signs in patients with TMDs and migraine. In patients with TMDs and simultaneous migraine, the LPM tends to be hypertrophic. LPM segmentation on MR imaging may be an alternative method to study this muscle in such patients because the hypertrophic LPM is not always palpable.

Anxiety and depression in brazilian undergraduate students: the role of sociodemographic variables, undergraduate course characteristics and social skills

The prevalence of anxiety and depression disorders in undergraduate students is high and several variables can be influential. The aim is to verify the predictive value of social skills, sociodemographic variables, and course characteristics for depression and anxiety. A total of 1282 students of a public university, of both sexes and from different years and courses, participated in this study. Screening instruments for depression and anxiety were applied, as well as an instrument investigating social skills and a questionnaire covering socio demographic indicators and course characteristics. The data were analyzed using univariate analysis followed by multiple binary regression analysis in order to define the relevance of these depression and anxiety measures. The rates of anxiety and depression were 19.4% and 3.8%, respectively. The social skills and living situation were predictive of depression, with the social skills and course area (with higher prevalence for the exact and human sciences) remaining in the final model for anxiety. Such data have implications for psychological prevention and intervention with this population.