Una aplicación del analisis de la supervivencia en ciencias de la salud

Este trabajo presenta las técnicas estadísticas mas utilizadas en ciencias de la salud para analizar datos de supervivencia con tiempos incompletos. A partir de un sencillo estudio, para valorar el efecto de diferentes variables pronósticas sobre el riesgo de recaída de heroinómanos recién deshabituados, se describe la estimación Kaplan-Meier y actuarial de las funciones de supervivencia y de riesgo, la comparación de curvas de supervivencia con la prueba de Mantel-Haenszel, el ajuste de un modelo de regresión de Cox y su uso predictivo. Se explica cómo interpretar practicamente los difeentes resultados obtenidos con [os programas 1L y 2L del Sistema BMDEThis paper describes the most used statistical methods for survival analysis of censored data in Health Sciences: the Kaplan-Meier and the actuarial estimation of the survival and hazard functions, the Mantel- Haenszel (Logrank) test for comparing survival distributions, the Cox regression model and how to fit the model to a set of data from a study for assessing the effects of prognostic covariates on the risk of recidive. The paper explains the predictive use of the model and how to interpret the results of the several analyses performed with 1L and 2L BMDP program

La contribución de la psicologia social al estudio de la ciencia

El articulo pretende mostrar la contribución que hasta ahora ha hecho la psicologia social al estudio de la ciencia, señalando sus principales carencias así como las posibles vias de superación de las mismas. Para ello, en prinzer lugar, los autores hacen una propuesta de clasificación temática de los trabajos realizados en el campo de la psicologia social de la ciencia. En segundo lugar, se señala la carencia de una perspectiva más social en este campo y se muestra como los psicólogos sociales críticos han tenido que recurrir a la sociologia para encontrar formulaciones sobre la ciencia y el conociemiento que les sean útiles. Finalmente, se exploran algunos de los aspectos que deberian ser tenidos en cuenta por una psicologia social que superara loss inconvenientes de la psicologia social de la ciencia más clásica. A la primera los autores la denominan psicologia social del conocimiento científicoThis paper presents the contributions of social psychology to the study of science. It highlights its weakerpoints, and suggests ways of overcoming them. First, the authors propose a thematic classification of the studies carried out in the field of social psychology. Second, they stress the need for a more social approach to the discipline. They explain how critical social psychologists have had to turn to sociolog)~to find useful tools to conceptualize science and knowledge. Finally: the article explores some of the aspects that should be considered by a socialpsychology that transcends the problems arising from the discipline's classical approach to science. The authors name their proposa1 "the social psychology of scientific knowledge

Captura de datos clínicos con verificación aleatoria : una nueva técnica para controlar y mejorar la calidad del registro

Este trabajo plantea las principales dificultades de la grabación de datos clínicos. Se ha diseñado una experiencia que consiste en capturar en un ordenador, en ausencia de protecciones automáticas, 335 entrevistas estructuradas codificadas previamente a mano por entrevistadores entrenados. El objetivo general del estudio consiste en valorar la eficacia de un nuevo sistema para controlar y mejorar la grabación: la verificación aleatoria (VA) de un porcentaje de cuestionarios, basada en el principio de «feedback». Para ello se han medido y tipificado los errores que cometen operadores profesionales durante la captura. Los objetivos específicos son: 1) valorar la eficacia de la VA respecto a la doble entrada (DE) - esta última constituye la estrategia habitual utilizada para mejorar la calidad del registro - ; 2) comprobar qué modalidades de error contienen los datos grabados; y 3) valorar la eficacia de los operadores para resolver las discrepancias aparecidas durante la verificación (midiendo qué porcentaje de errores persiste en los campos con discordancias durante la segunda captura de la VA y la DE). Los resultados principales indican que la VA ofrece un rendimiento similar a la DE con distintos operadores, mientras que la entrada simple y la DE con un mismo operador no constituyen sistemas eficaces para garantizar la calidad del registro. En la discusión se destacan qué aspectos de la medición y de la captura de datos se mejoran usando controles informáticos, qué requisitos mínimos de calidad deben prevalecer durante la grabación y qué elementos requieren los sistemas informáticos para operar de forma eficienteThis work contemplates the main difficulties related to the capture of clinical data into the computer. We have designed an experience that consists of capturing into the computer, in absence of automatic protections, 335 structured interviews coded on paper by trained interviewers. The general objective of this study consists of rating the efficiency of a new computerized system (based on the feedback principle) for controlling and improving the capture: the random verification (RV) of a percentage of questionnaires. To accomplish this objective, we have measured and classified the mistakes that professional operators commit during the data capture. The specific objectives are: 1) to rate the efficiency of the RV compared to double entry (DE) - this last strategy is the most commonly used for improving the quality of the capture -; 2) to check the types of mistakes contained in the recorded data; and 3) to rate the operators' efficiency for resolving the discrepancies that appeared during verification (through the measurement of the mistakes that persist in the fields with disagreements during the second capture of the RV and the DE). The principle results obtained indicate that the RV and the DE with different operators offer similar performance, while the simple entry and the DE with only one operator do not constitute effective systems for guaranteeing the quality of the capture. In the discussion we emphasize what aspects of the measurement and the data capture are improved using computerized controls, what minimum quality requirements should be present during the recording and what elements the computerized systems require for operating efficientl

Percepciones de los ciudadanos catalanes acerca de la participación del público y los expertos en las controversias sobre el agua

La gestión sostenible del agua ha aparecido en España como el centro de una controversia de primera magnitud. En ella, la participación ciudadana es un eje fundamental. A partir del análisis de grupos de discusión realizados en seis ciudades de Cataluña, este trabajo reflexiona sobre la percepción de la participación en los debates sobre el agua. Se presentan cinco actores que aparecen en el discurso de los entrevistados: los «expertos», los «perjudicados », los «beneficiados», los «interesados» y los «concienciados». Posteriormente, se examinan los criterios que permiten identificar, entre estos actores, los que son considerados legítimos en las controversias hidrológicas.Sustainable water management has become the focal point of a highly important issue in Spain. Citizens' participation in this controversy it is fundamental. Having carried out the analysis of several focus groups in six Catalonian cities (Spain), this study reflects on the perception of participating in discussions on water. Five actors mentioned in interviewees' discourse are presented: the «experts», the «affected», the «benefited», the «interested», and the «conscious». Then, the criteria permitting to identify among these actors those considered to be legitimate participants in hydrological controversies are examined

Una propuesta para el análisis de respuestas binarias en diseños 'cross-over'

Se realiza una aproximación a la problemática que presenta el análisis del diseño «cross-over» cuando la variable dependiente es binaria. Se presentan las posibilidades que ofrece la regresión logística condicional exacta implementada en la aplicación LogXact, para abordar el análisis de este diseño. Se ilustra de forma práctica el uso de LogXact en torno a los datos de un estudio sobre la decisión de adoptar precauciones contra la infección ocupacional por VIH, en el que además del efecto del tratamiento se evalúan simultáneamente los efectos de período y de «carry-over»This paper focuses on the problems derived from the analysis of cross-over designs with binary dependent variables. In order to approach this analysis, we present those possibilities offered by a conditional exact logistic regression implemented to LogXact application. We illustrate the use of LogXact based on data from a study on decisions to take precautions against HIV infection in work environment. Besides the treatment effect, we simultaneously evaluate those effects of period and carry-ove

Factors related to the comorbidity between oppositional defiant disorder and anxiety disorders in preschool children

Background: The aim of the study is to identify the main factors related to comorbid oppositional defiant disorder (ODD) and anxiety disorders (AD), for preschoolers, and to assess the moderating role of the children's sex. Design: The initial sample of 622 children was assessed longitudinally at the ages of 3 and 5 years by means of questionnaires and a diagnostic interview. At baseline, there were 310 boys (49.8%), most participants were of Caucasian-white ethnicity (554, 89.1%), 398 children attended to public school (64.0%) and families socioeconomic status was 64.3% medium-high, 14.1% medium and 20.5% medium-low or low levels. Methods: For the analysis, children diagnosed with ODD and/or AD were selected: n=103 at 3 years old (44 ODD, 42 AD and 17 ODD+AD) and n=106 at 5 years old (31 ODD, 60 AD and 15 ODD+AD). Results: High levels of the child's negative affectivity and the mother's aggressive behavior (versus AD), and high scores in the father's psychopathology measurements (versus ODD) are related to the presence of comorbid ODD+AD at the age of 3. High scores in the child's approach-positive anticipation, fears (only in boys, in girls the reverse effect occurred) compared to ODD and AD independently and aggressive behavior (versus AD), and low scores for smiling and laughter (versus ODD only and AD only) are predictive of comorbidity at the age of 5. Conclusions: Temperament traits may be a common factor in explaining longitudinal ODD+AD comorbidity

Developmental trajectories of callous-unemotional traits, anxiety and oppositional defiant disorder in 3 - 7 year-old children in the general population

There is increasing interest in describing different variants and subtypes that characterize the heterogeneity of behavior problems with the aim of supporting early detection and prevention, as well as facilitating research into etiological differences. This work examines the course of co-occurrence of callous-unemotional traits (CU), anxiety (ANX) and oppositionality (ODD-s) levels in a longitudinal community sample. A sample of 622 3-year-old preschoolers, followed up until age 7, was assessed annually with dimensional measures of callous-unemotional traits, oppositional defiant disorder and anxiety and related psychological constructs answered by parents, teachers and performed by children. Growth-Mixture-Modeling yielded six trajectories (null 58.9%, ANXincreasing 4.9%, CU + ANX + ODD 2.4%, CU + ODD-decreasing 8.1%, ODD-increasing 16.4%, and ANX-decreasing 9.2%) that represent the variants previously described with older subjects. The specifier ODD "with limited prosocial emotion" (CU + ODD decreasing and increasing) showed deficits in executive functioning, attention, aggressive behavior and social cognition in comparison with null trajectory. The secondary variant showed a more severe clinical picture and presented more difficulties in executive functioning, worse environmental characteristics, and worse outcomes at age 7. It is possible to identify the heterogeneity of disruptive behavior problems from preschool age. The identification of homogeneous groups in this category of disorders may help to design more suitable treatments with specific components for specific difficulties, and to progress in the etiological research of each clas

Clinical characteristics of preschool children with oppositional defiant disorder and callous-unemotional traits

There is a need to know whether callous-unemotional (CU) traits identify a more severe group of oppositional defiant children (ODD). The aim of this study is to ascertain cross-sectionally and longitudinally the specific contribution of CU levels and the presence of ODD in the psychological state of preschool children from the general population. A total of 622 children were assessed longitudinally at ages 3 and 5 with a semi-structured diagnostic interview and questionnaires filled out by parents and teachers. In multivariate models simultaneously including ODD diagnosis and CU levels, controlling by socioeconomic status, ethnicity, sex, severity of conduct disorder symptoms and other comorbidity, high CU scores were related to higher levels of aggression, withdrawn, externalizing and global symptomatology, functional impairment and higher probability of comorbid disorders and use of services. The contribution of CU traits on children's psychological state was not moderated by the presence/absence of ODD. Stability for CU traits and number of ODD-symptoms between ages 3 and 5 was statistically significant but moderate-low (intra-class correlation under .40). Assessment and identification of CU traits from preschool might help to identify a subset of children who could have socialization problems, not only among those with ODD but also among those without a diagnosis of conduct problem

Obesity, diet and restrained eating in a mediterranean population

OBJECTIVE: To evaluate links between obesity, gender and restrained eating in a representative sample of adolescents in Catalonia (Spain). DESIGN: Several surveys and measurements are applicated to a sample of adolescents from schools in the city of Barcelona. SUBJECTS: 525 subjects (57% girls and 43% boys) aged from 15-18 from 22 schools in the city of Barcelona. MEASUREMENTS: Weight, height, ideal weight, percentage of relative weight asmeasurement of obesity, subscale "Diet" of the Eating Attitudes Test as measurement of concern for dieting, and subjects' negative or affirmative responses to the question as to whether they were following a diet at the time of the study. RESULTS: The prevalence of obesity in the sample ist of 17.1%. 14.3% presented mild obesity and 2.9% presented moderate obesity. Not one case of severe obesity was recorded. Dieting greatly affects normal-weight infant-juvenile populations in Spain. Girls are more concerned about dieting and are more likely to follow a diet independent of the extent to which they are overweight. Obese subjects are more likely to have higher concern for diet and to be on a diet than those of normal-weight. The restrained behaviour observed in obese subjects, is not related to the type of restraint which is evaluated using tools such as the "Diet" subscale of the EAT. CONCLUSION: We coincide in reporting a lower prevalence of obesity in Spain (an european sample) than in the United States. But the obesity's prevalence is not insignificant. It would appear that the degree of excess weight and the restraint boundary have no lineal relationship. The prevalence of restrained eating behaviour among young adolescents in Spain is high. Given the dangers of such attitudes, it is becoming increasingly necessary to develop preventive programmes to combat the