Factors associated with Leishmania chagasi infection in domestic dogs from Teresina, State of Piauí, Brazil

INTRODUCTION: Many studies have evaluated risk factors for human visceral leishmaniasis, but few have focused on the infection among dogs. The objective of this study was to assess the association between peridomestic socioeconomic and environmental factors and the presence of dogs seropositive for Leishmania chagasi in the City of Teresina, Brazil. METHODS: This case-control study was based on the results of a routine seroepidemiological survey among domestic dogs carried out in 2007. Serological tests were performed by means of indirect immunofluorescence antibody test. All dwellings in which at least one seropositive dog was detected were considered cases, and controls were a random sample of dwellings in which only seronegative dogs were identified. Associations between variables were expressed as odds ratios (OR) and their respective 95% confidence intervals (95%CI) estimated using multivariate logistic regression. RESULTS: Dwellings with a history of dogs removed by the visceral leishmaniasis control program in the last 12 months had five-fold higher odds of having at least one seropositive dog as compared with dwellings having no history of dog removal (OR = 5.19; 95%CI = 3.20-8.42). Dwellings with cats had 58% increased odds of dog infection as compared with those having no cats (OR = 1.58; 95%CI = 1.01-2.47). CONCLUSIONS: Identification of factors associated with canine visceral leishmaniasis might be used for the delimitation of areas of higher risk for human visceral leishmaniasis, since infection in dogs generally precedes the appearance of human cases.

Credit default swap (CDS) prediction model & trading strategy

This project focuses on the study of different explanatory models for the behavior of CDS security, such as Fixed-Effect Model, GLS Random-Effect Model, Pooled OLS and Quantile Regression Model. After determining the best fitness model, trading strategies with long and short positions in CDS have been developed. Due to some specifications of CDS, I conclude that the quantile regression is the most efficient model to estimate the data. The P&L and Sharpe Ratio of the strategy are analyzed using a backtesting analogy, where I conclude that, mainly for non-financial companies, the model allows traders to take advantage of and profit from arbitrages.

Prevalence and factors associated with HCV infection among elderly individuals in a southern Brazilian city

Introduction Few Latin American studies have assessed the prevalence of hepatitis C virus (HCV) infection in elderly individuals, in whom the highest rates are expected. We aimed to investigate the prevalence of and factors associated with HCV infection in elderly residents in the municipality of Tubarão, Santa Catarina. Methods This cross-sectional study included 820 individuals (aged ≥ 60 years) who were selected by simple random sampling. The presence of anti-HCV antibodies was tested by chemiluminescence, and HCV RNA detection was performed for the anti-HCV-reactive subjects. Those individuals who were anti-HCV reactive but had undetectable HCV RNA levels were tested using a third-generation recombinant immunoblot assay. The variables were compared using the chi-squared test or Fisher's exact test, and those variables with p < 0.05 were included in the logistic regression model. Results The mean patient age was 68.6 years (SD 7.0 years); 39% were men, and 92% were Caucasian. Eighteen subjects were anti-HCV positive. Among these individuals, 4 were characterized as false-positives, leaving 14 (1.7%) individuals with confirmed infections for analysis. HCV infection was associated with an age older than 65 years, households with 3 or more residents and the previous transfusion of blood products. In the logistic regression analysis, the following variables were independently associated with HCV infection: households with 3 or more residents (OR 7.9, 95% CI 1.7–35.9, p = 0.008) and previous blood transfusion (OR 6.2, 95% CI 2.1–18.6, p = 0.001). Conclusions The HCV prevalence in the elderly population in the municipality of Tubarão was higher than that found in previous studies of blood donors in the same region. Although exposure to contaminated blood products remained important, other transmission routes, such as household transmission, could play a role in HCV infection.

Post-merger innovative performance in the renewable energy sector

Due to global warming and shrinking fossil fuel resources, politics as well as society urge for a reduction of green house gas (GHG) emissions. This leads to a re-orientation towards a renewable energy sector. In this context, innovation and new technologies are key success factors. Moreover, the renewable energy sector has entered a consolidation stage, where corporate investors and mergers and acquisitions (M&A) gain in importance. Although both M&A and innovation in the renewable energy sector are important corporate strategies, the link between those two aspects has not been examined before. The present thesis examines the research question how M&A influence the acquirer’s post-merger innovative performance in the renewable energy sector. Based on a framework of relevant literature, three hypotheses are defined. First, the relation between non-technology oriented M&A and post-merger innovative performance is discussed. Second, the impact of absolute acquired knowledge on postmerger innovativeness is examined. Third, the target-acquirer relatedness is discussed. A panel data set of 117 firms collected over a period of six years has been analyzed via a random effects negative binomial regression model and a time lag of one year. The results support a non-significant, negative impact of non-technology M&A on postmerger innovative performance. The applied model did not support a positive and significant impact of absolute acquired knowledge on post-merger innovative performance. Lastly, the results suggest a reverse relation than postulated by Hypothesis 3. Targets from the same industry significantly and negatively influence the acquirers’ innovativeness.

Do hospitals react to random demand pressure by early discharges?

This project tries to assess whether hospitals react to random demand pressure by discharging patients earlier than expected. As a matter of fact, combining an unpredictable demand for medical services with limited and, to some extent, fixed medical resources, generates strong incentives to discharge patients earlier than expected when demand is high − increasing the risk of readmission and decreasing the benefit from treatment. This work was conducted as a way to determine whether those incentives actually affect discharging decisions. Analysis of Portuguese hospitals data shows that hospital utilization levels at the time of admission, prior to the admission and post admission do have a negative impact over the length of stay in hospital, although this impact is quantitatively irrelevant. More than that, larger utilization levels have a positive impact over the probability of being discharged at certain days of the week, indicating that an early discharges problem may exist.

Geographic weighted regression: applicability to epidemiological studies of leprosy

Abstract: INTRODUCTION: Geographic information systems (GIS) enable public health data to be analyzed in terms of geographical variability and the relationship between risk factors and diseases. This study discusses the application of the geographic weighted regression (GWR) model to health data to improve the understanding of spatially varying social and clinical factors that potentially impact leprosy prevalence. METHODS: This ecological study used data from leprosy case records from 1998-2006, aggregated by neighborhood in the Duque de Caxias municipality in the State of Rio de Janeiro, Brazil. In the GWR model, the associations between the log of the leprosy detection rate and social and clinical factors were analyzed. RESULTS: Maps of the estimated coefficients by neighborhood confirmed the heterogeneous spatial relationships between the leprosy detection rates and the predictors. The proportion of households with piped water was associated with higher detection rates, mainly in the northeast of the municipality. Indeterminate forms were strongly associated with higher detections rates in the south, where access to health services was more established. CONCLUSIONS: GWR proved a useful tool for epidemiological analysis of leprosy in a local area, such as Duque de Caxias. Epidemiological analysis using the maps of the GWR model offered the advantage of visualizing the problem in sub-regions and identifying any spatial dependence in the local study area.

Using data mining for prediction of hospital length of stay: an application of the CRISP-DM Methodology

Hospitals are nowadays collecting vast amounts of data related with patient records. All this data hold valuable knowledge that can be used to improve hospital decision making. Data mining techniques aim precisely at the extraction of useful knowledge from raw data. This work describes an implementation of a medical data mining project approach based on the CRISP-DM methodology. Recent real-world data, from 2000 to 2013, were collected from a Portuguese hospital and related with inpatient hospitalization. The goal was to predict generic hospital Length Of Stay based on indicators that are commonly available at the hospitalization process (e.g., gender, age, episode type, medical specialty). At the data preparation stage, the data were cleaned and variables were selected and transformed, leading to 14 inputs. Next, at the modeling stage, a regression approach was adopted, where six learning methods were compared: Average Prediction, Multiple Regression, Decision Tree, Artificial Neural Network ensemble, Support Vector Machine and Random Forest. The best learning model was obtained by the Random Forest method, which presents a high quality coefficient of determination value (0.81). This model was then opened by using a sensitivity analysis procedure that revealed three influential input attributes: the hospital episode type, the physical service where the patient is hospitalized and the associated medical specialty. Such extracted knowledge confirmed that the obtained predictive model is credible and with potential value for supporting decisions of hospital managers.

Extreme value Birnbaum-Saunders regression models applied to environmental data

Extreme value models are widely used in different areas. The Birnbaum–Saunders distribution is receiving considerable attention due to its physical arguments and its good properties. We propose a methodology based on extreme value Birnbaum–Saunders regression models, which includes model formulation, estimation, inference and checking. We further conduct a simulation study for evaluating its performance. A statistical analysis with real-world extreme value environmental data using the methodology is provided as illustration.

Food consumption of adolescents. A simplified questionnaire for evaluating cardiovascular risk

OBJECTIVE: To develop a simplified questionnaire for self-evaluation by adolescents of foods associated with the risk of coronary diseases. METHODS: Frequency questionnaires about 80 foods were answered by representative samples of 256 adolescents aged 12 to 19 from Rio de Janeiro as part of the Nutrition and Health Research project. The dependent variable was the serum cholesterol predicting equation as influenced by diet, and the independent variables were the foods. The variables were normalized and, using Pearson's correlation coefficient, those with r>0.10 were selected for the regression model. The model was analyzed for sex, age, random sample, and total calories. Those food products that explained 85% of the cholesterol variation equation were present in the caloric model, and contained trans fatty acids were selected for the questionnaire. RESULTS: Sixty-five food products had a statistically significant correlation (P<0.001) with the dependent variable. The simplified questionnaire included 9 food products present in all tested models: steak or broiled meat, hamburger, full-fat cheese, French fries or potato chips, whole milk, pies or cakes, cookies, sausages, butter or margarine. The limit of the added food points for self-evaluation was 100, and over 120 points was considered excessive. CONCLUSION: The scores given to the food products and the criteria for the evaluation of the consumption limits enabled the adolescents to get to know and to balance their intake.

Random walk forecast of urban water in Iran under uncertainty

There are two significant reasons for the uncertainties of water demand. On one hand, an evolving technological world is plagued with accelerated change in lifestyles and consumption patterns; and on the other hand, intensifying climate change. Therefore, with an uncertain future, what enables policymakers to define the state of water resources, which are affected by withdrawals and demands? Through a case study based on thirteen years of observation data in the Zayandeh Rud River basin in Isfahan province located in Iran, this paper forecasts a wide range of urban water demand possibilities in order to create a portfolio of plans which could be utilized by different water managers. A comparison and contrast of two existing methods are discussed, demonstrating the Random Walk Methodology, which will be referred to as the â On uncertainty pathâ , because it takes the uncertainties into account and can be recommended to managers. This On Uncertainty Path is composed of both dynamic forecasting method and system simulation. The outcomes show the advantage of such methods particularly for places that climate change will aggravate their water scarcity, such as Iran.

Prevalencia de Trastornos Mentales en consultantes de Centros de Atención Primaria de la Ciudad de Córdoba, Argentina.Prevalence of Mental Disorders among Consultants in Primary Health Care Centers of the City of Córdoba, Argentina

El informe de la Organización Mundial de la Salud (2001), refiere que en un plazo de 20 años los trastornos mentales pasarán a ser la segunda causa dentro de la carga de morbilidad a nivel mundial, y en la actualidad una de cada cuatro personas padece de algún trastorno mental en alguna etapa de su vida. Los estudios realizados en diversos países revelan que una proporción importante de los consultantes de la atención primaria en salud presentan algún tipo de trastornos mentales. Desde esta perspectiva, la atención primaria de la salud ofrece una oportunidad de intervenir en el manejo de los trastornos mentales de forma temprana y eficaz. En Argentina, es limitada la información acerca del registro epidemiológico en salud mental, no contando con estudios abordados desde la Atención Primaria en la provincia de Córdoba. El objetivo general del proyecto es estimar la prevalencia de trastornos mentales entre los consultantes de atención primaria por problemas de salud general. Para ello se propone: Estimar la prevalencia de trastornos mentales en una muestra representativa de consultantes adultos por problemas de salud general, de centros de atención primaria de la ciudad de Córdoba, identificar y describir los tipos de trastornos mentales que presentan estos consultantes adultos de centros de atención primaria y analizar la prevalencia de los trastornos mentales por sexo y edad de la población en estudio. Metodología: el estudio se realizará en consultorios de Atención Primaria de Salud distribuídos en todo el éjido de la ciudad, teniendo en cuenta la representación de las 12 zonas de CPC. La muestra es probabilística, estratificada, polietápica de pacientes que consultan en el primer nivel de atención. Se entrevistarán 1200 pacientes utilizando la versión computorizada del CIDI 3.0, que proporciona diagnóstico de acuerdo a la DSM IV y la CIE-10. La confiabilidad y la validez del instrumento ha sido ampliamente documentada y la traducción de la encuesta al español fue realizada conforme a las recomendaciones de la OMS. El análisis efectuado será de prevalencia de Trastornos Mentales y del Comportamiento (TMC),asociación entre factores sociodemográficos y TCM estimados calculando las razones de disparidad (odds ratio), regresión logística a fin de ajustar los resultados por la posible interacción entre variables, análisis de la asociación de todas las variables con los TMC, análisis univariado de la asociación de cada variable con los TMC, controlando sexo y edad, se construirá un modelo de regresión logística. En todos los casos el nivel de significación será de 0,05. El equipo de trabajo, de cooperación internacional entre profesionales de la UNC y de la Universidad de Chile, y con la participación en colaboración de los profesionales dependientes de la Secretaría de Salud de la municipalidad de Córdoba, representa un avance para trabajar en los centros de salud de esta ciudad, constituyéndose en un avance, cualitativo y cuantitativo de la actividad científica en Atención Primaria en salud mental con abordaje epidemiológico. Se espera contribuir al conocimiento acerca de la prevalencia de los problemas de salud mental de esta población en la ciudad de Córdoba, proporcionando información a los funcionarios y responsables por la gestión de las áreas vinculadas a la salud mental, aportando conocimiento que promueva una temprana identificación de riesgos iniciales en salud mental y conductas de cuidado en la población como potencial de bienestar.Así mismo, se espera sistematizar una experiencia que pueda ser replicada en otros sitios geográficos. Por todo lo anterior, esta propuesta permitirá conocer por primera vez en la ciudad de Córdoba la frecuencia y características de los problemas de salud mental entre consultantes de Atención Primaria, información fundamental para el desarrollo posterior de estrategias que busquen mejorar la detección y el tratamiento de estos problemas. According to the WHO Report (2001), in 20 years, mental health disorders (MHDs) will be the world’s second most frequent cause of morbidity. Primary care offers the opportunity to handle MHDs efficiently at an early stage. In Argentina, the epidemiologic data on mental health (MH) is limited, and there are no records for Córdoba. The aim of this project is to assess the prevalence of MHDs among consultants who resort to primary health centers (PHCCs) in the city of Córdoba for common health problems, by using a representative sample of adult consultants, identifying and describing the types of MHDs evinced, and analysing prevalence by sex and age group under study. Methodology:the study will be carried out in PHCCs located in the municipal area of Córdoba, covering the 12 zones corresponding to the CPCs (municipal branch offices for each zone). A multi-stage stratified random sample of 1200 patients will be interviewed using the program CIDI 3.0 to produce a diagnostic according to DSM IV and CIE-10, a tool with proven reliability and validity.The aspects to be analysed are prevalence of mental and behavior disorders, their association with socio-demographic factors estimated by odds ratios, logistic regression for adjustment of potential interaction among variables, association with all variables, and univariate analysis for association with each variable. Significance level will be 0.05 in all cases. The international teamwork including professionals from the Universities of Córdoba, Chile and the Public Health Department of the Municipality of Córdoba constitutes a qualitative and quantitative step forward in the field of primary health care studies with an epidemiologic approach. This project aims at providing administrators in the MH area with data for the early detection of initial risks in MH and the promotion of prevention habits. This will be the first study conducted in Córdoba, and is aimed at facilitating replication in other geographical areas.

Blood Pressure Control in Hypertensive Patients in the "Hiperdia Program": A Territory-Based Study

Background:Systemic hypertension is highly prevalent and an important risk factor for cardiovascular events. Blood pressure control in hypertensive patients enrolled in the Hiperdia Program, a program of the Single Health System for the follow-up and monitoring of hypertensive patients, is still far below the desired level.Objective:To describe the epidemiological profile and to assess blood pressure control of patients enrolled in Hiperdia, in the city of Novo Hamburgo (State of Rio Grande do Sul, Brazil).Methods:Cross-sectional study with a stratified cluster random sample, including 383 adults enrolled in the Hiperdia Program of the 15 Basic Health Units of the city of Porto Alegre, conducted between 2010 and 2011. Controlled blood pressure was defined as ≤140 mmHg × 90 mmHg. The hypertensive patients were interviewed and their blood pressure was measured using a calibrated aneroid device. Prevalence ratios (PR) with 95% confidence interval, Wald's χ2 test, and simple and multiple Poisson regression were used in the statistical analysis.Results:The mean age was 63 ± 10 years, and most of the patients were females belonging to social class C, with a low level of education, a sedentary lifestyle, and family history positive for systemic hypertension. Diabetes mellitus (DM) was observed in 31%; adherence to the antihypertensive treatment in 54.3%; and 33.7% had their blood pressure controlled. DM was strongly associated with inadequate BP control, with only 15.7% of the diabetics showing BP considered as controlled.Conclusion:Even for hypertensive patients enrolled in the Hiperdia Program, BP control is not satisfactorily reached or sustained. Diabetic hypertensive patients show the most inappropriate BP control.

Experimental design for mixed models with application to population pharmacokinetic studies

experimental design, mixed model, random coefficient regression model, population pharmacokinetics, approximate design

Association between LDL-C, Non HDL-C, and Apolipoprotein B Levels with Coronary Plaque Regression

Background:Previous reports have inferred a linear relationship between LDL-C and changes in coronary plaque volume (CPV) measured by intravascular ultrasound. However, these publications included a small number of studies and did not explore other lipid markers.Objective:To assess the association between changes in lipid markers and regression of CPV using published data.Methods:We collected data from the control, placebo and intervention arms in studies that compared the effect of lipidlowering treatments on CPV, and from the placebo and control arms in studies that tested drugs that did not affect lipids. Baseline and final measurements of plaque volume, expressed in mm3, were extracted and the percentage changes after the interventions were calculated. Performing three linear regression analyses, we assessed the relationship between percentage and absolute changes in lipid markers and percentage variations in CPV.Results:Twenty-seven studies were selected. Correlations between percentage changes in LDL-C, non-HDL-C, and apolipoprotein B (ApoB) and percentage changes in CPV were moderate (r = 0.48, r = 0.47, and r = 0.44, respectively). Correlations between absolute differences in LDL-C, non‑HDL-C, and ApoB with percentage differences in CPV were stronger (r = 0.57, r = 0.52, and r = 0.79). The linear regression model showed a statistically significant association between a reduction in lipid markers and regression of plaque volume.Conclusion:A significant association between changes in different atherogenic particles and regression of CPV was observed. The absolute reduction in ApoB showed the strongest correlation with coronary plaque regression.

Optimal designs for mixed effects poisson regression models

Magdeburg, Univ., Fak. für Mathematik, Diss., 2010