This article replies to the defense of the supermajority system established in the Chilean Constitution, recently published by Sergio Verdugo. After verifying a tie between the reasons in favor and against supermajorities in the scope of general justification, Verdugo proposes starting to discuss specifically each of the rules for qualified quorum . This article rebuts both Verdugo's strategy and his general and special argumentation to justify the rules for supermajority quorums. The background of this article is made up by a defense of the link between simple majority and democracy.

Este artículo constituye una réplica a la defensa del sistema de súper-mayorías que establece la Constitución chilena, recientemente publicado por Sergio Verdugo. Tras verificar un empate entre las razones a favor y en contra de las súper-mayorías en el plano de la justificación general, Verdugo propone pasar a discutir cada una de las reglas de quórum calificado en específico. Este artículo rebate tanto la estrategia de Verdugo como sus argumentos generales y especiales para justificar las reglas de quórums súper-mayoritarios. El telón de fondo de este artículo está dado por una defensa de la conexión entre mayoría simple y democracia.

OBJETIVOS: Desenvolver um modelo de predição para o tempo de permanência hospitalar (TPH) em lactentes de muito baixo peso ao nascer (MBPN) e comparar esse resultado entre 20 centros de uma rede neonatal, visto que o TPH é utilizado como uma medida da qualidade da assistência em lactentes de MBPN. MÉTODOS: Utilizamos dados coletados prospectivamente de 7.599 lactentes com peso ao nascer entre 500 e 1.500 g no período entre os anos de 2001 a 2008. O modelo de regressão de Cox foi empregado para desenvolver dois modelos de predição: um modelo prévio com dados do nascimento e outro posterior, que acrescenta morbidades relevantes dos primeiros 30 dias de vida. RESULTADOS: A mediana do TPH estimado e ajustado a partir do nascimento foi de 59 dias; 28 dias depois do tempo de sobrevida de 30 dias. Houve uma alta correlação entre os modelos (r = 0,92). O TPH esperado e o TPH observado variaram bastante entre os centros, mesmo depois de correção para as morbidades relevantes após 30 dias. O TPH mediano (variação: 45-70 dias) e a idade concepcional na alta hospitalar (variação: 36,4-39,9 semanas) refletem uma variabilidade alta entre centros. CONCLUSÃO: Um modelo simples, com fatores apresentados no nascimento, pode predizer o TPH de um lactente de MBPN em uma rede neonatal. Observou-se uma variabilidade nos TPHs considerável entre unidades de terapia intensiva neonatal. Especulamos que os resultados sejam provenientes das diferenças entre as práticas dos centros.

OBJECTIVES: To develop a prediction model for hospital length of stay (LOS) in very low birth weight (VLBW) infants and to compare this outcome among 20 centers within a neonatal network. METHODS: Data from 7,599 infants with birth weights of 500-1,500 g born between the years 2001-2008 were prospectively collected. The Cox regression model was employed to develop two prediction models: an early model based upon variables present at birth, and a late one that adds relevant morbidities for the first 30 days of life. RESULTS: Median adjusted estimated LOS from birth was 59 days ‒ 28 days after 30-day point of survival. There was a high correlation between models (r = 0.92). Expected/observed LOS varied widely among centers, even after correction for relevant morbidity after 30 days. Median observed LOS (range: 45-70 days), and postmenstrual age at discharge (range: 36.4-39.9 weeks) reflect high inter-center variability. CONCLUSION: A simple model, with factors present at birth, can predict a VLBW infant's LOS in a neonatal network. Significant variability in LOS was observed among neonatal intensive care units. We speculate that the results originate in differences in inter-center practices.

Unit non-response is a growing problem in sample surveys that can bias survey estimates if respondents and non-respondents differ systematically. Objetives: To compare the results of two nonresponse adjustment methods: field substitution and weighting nonresponse adjustment based on response propensity. Methods: Field substitution and response propensity weights are used to adjust for non-response and their effect on the prevalence of six survey outcomes is compared. Results Although significant differences are found between respondents and non-respondents, only slight changes on prevalence estimates are observed after adjustment, with both techniques showing similar results. In the sole case of smoking, substitution seems to have further biased survey estimates. Conclusions: Our results suggest that when there is information available for both respondents and non-respondents, or if a careful sample substitution process is performed, weighting adjustments based on response propensity and field substitution produce comparable results on prevalence estimates.

La no respuesta es un problema creciente en encuestas poblacionales que puede ser causa de sesgo de no-respuesta cuando respondedores y no respondedores difieren sistemáticamente. Objetivo: Comparar los resultados obtenidos mediante dos técnicas de corrección para el sesgo de no-respuesta: sustitución muestral y pesos de no respuesta obtenidos mediante propensión a responder. Métodos: Se comparan los efectos de la sustitución muestral semicontrolada y el uso de pesos de ajuste obtenidos mediante la propensión a responder sobre seis resultados de una encuesta de salud. Resultados: A pesar de las diferencias significativas entre respondedores y no respondedores, mediante la corrección las prevalencias estimadas sólo cambian levemente, dando ambas técnicas de ajuste resultados similares. Sólo en el caso del tabaquismo, la sustitución muestral parece haber aumentado el sesgo de la estimación. Conclusiones: Nuestros resultados sugieren que tanto mediante un procedimiento de sustitución muestral semicontrolada, como a través del ajuste estadístico de la no respuesta mediante la propensión a responder, se obtienen estimaciones de prevalencias corregidas similares.

Unit non-response is a growing problem in sample surveys that can bias survey estimates if respondents and non-respondents differ systematically. Objetives: To compare the results of two nonresponse adjustment methods: field substitution and weighting nonresponse adjustment based on response propensity. Methods: Field substitution and response propensity weights are used to adjust for non-response and their effect on the prevalence of six survey outcomes is compared. Results Although significant differences are found between respondents and non-respondents, only slight changes on prevalence estimates are observed after adjustment, with both techniques showing similar results. In the sole case of smoking, substitution seems to have further biased survey estimates. Conclusions: Our results suggest that when there is information available for both respondents and non-respondents, or if a careful sample substitution process is performed, weighting adjustments based on response propensity and field substitution produce comparable results on prevalence estimates.

La no respuesta es un problema creciente en encuestas poblacionales que puede ser causa de sesgo de no-respuesta cuando respondedores y no respondedores difieren sistemáticamente. Objetivo: Comparar los resultados obtenidos mediante dos técnicas de corrección para el sesgo de no-respuesta: sustitución muestral y pesos de no respuesta obtenidos mediante propensión a responder. Métodos: Se comparan los efectos de la sustitución muestral semicontrolada y el uso de pesos de ajuste obtenidos mediante la propensión a responder sobre seis resultados de una encuesta de salud. Resultados: A pesar de las diferencias significativas entre respondedores y no respondedores, mediante la corrección las prevalencias estimadas sólo cambian levemente, dando ambas técnicas de ajuste resultados similares. Sólo en el caso del tabaquismo, la sustitución muestral parece haber aumentado el sesgo de la estimación. Conclusiones: Nuestros resultados sugieren que tanto mediante un procedimiento de sustitución muestral semicontrolada, como a través del ajuste estadístico de la no respuesta mediante la propensión a responder, se obtienen estimaciones de prevalencias corregidas similares.

OBJECTIVES: To evaluate the clinical severity and proportionality of small for gestational age, very low birth weight neonates (< 1,500 g) and to estimate the neonatal mortality risk associated with the condition of being small for gestational age according to the degree of severity and proportionality. METHODS: Observational design. All of the NEOCOSUR Collaborative Group's very low birth weight infants (25-36 weeks' gestation) were included (n = 1,518). Anthropometric indices: birth weight < 3rd and 10th percentile. Severity (fetal growth ratio = observed weight/mean birth weight for gestational age); no growth restriction: fetal growth ratio 0.90-1.10, mild: fetal growth ratio 0.80-0.89, moderate: fetal growth ratio 0.75-0.79 and severe: fetal growth ratio < 0.75. Proportionality: coefficient of bimodality and z score for ponderal index (PI = g/cm³ *100). Neonatal mortality until discharge. RESULTS: < 3rd percentile: 13.5% (p < 0.001); < 10th percentile: 31% (p < 0.001); fetal growth ratio: 0.90±0.21 (p < 0.001), mild restriction: 20.8%, moderate restriction: 8.7% and severe restriction: 32.6%. Coefficient of bimodality: 0.53; PI z score < -1: 8%. Maternal hypertensive disease was systematically associated with being small for gestational age (aOR 1.20, 95% CI 0.86-1.67), fetal growth ratio < 0.89 (aOR 1.71, 1.24-2.36) and PI z score < -1 (aOR 1.60, 1.03-2.41). Adjusted odds ratios for neonatal mortality were: 2.64 (95% CI 1.71-3.92) for being small for gestational age, 2.76 (95% CI 1.85-4.10) for fetal growth ratio < 0.89, and 1.37 (95% CI 0.80-2.32) for z score PI < -1. CONCLUSIONS: Small for gestational age, mostly symmetric and severe restriction is a frequent condition in < 1,500 g neonates and is associated with higher mortality rates.

OBJETIVOS: 1) evaluar la severidad y la proporcionalidad de los PEG para diferentes grados de prematurez; 2) estimar el riesgo de mortalidad de los PEG según la severidad y proporcionalidad. MATERIAL Y MÉTODOS: Diseño observacional y analítico. Población: todos los recién nacidos de muy bajo peso (RNMPB) entre 25 y 36 semanas que mantiene el grupo NEOCOSUR (n = 1.518). Índices antropométricos: a) peso de nacimiento (PN) < percentil 3 y 10; b) severidad (FGR, razón del crecimiento fetal - razón entre el PN observado y la media del PN para cada edad gestacional): normal: FGR 0,90-1,10, leve: 0,80-0,89, moderado: 0,75-0,79 y severo < 0,75; c) proporcionalidad: estimada por el Coeficiente de Bimodalidad (disarmónico: > 0,55) y la transformación z del índice ponderal (Ponderal Index, PI = g/cm³ x 100). Restricción del crecimiento intrauterino (RCIU) asimétrico: score z < -1. Mortalidad neonatal hasta el alta. RESULTADOS: PN < perc. 3: 13,5%; < perc. 10: 30,7%; FGR: 0,90±0,21; FGR leve 20,8%, moderado 8,7% y severo 32,6%. Coef. Bimodalidad: 0,53; índice ponderal: 2,27±0,51. Score z: 0,007±1,0; score z <-1: 7,9. La hipertensión materna se asoció con los riesgos ajustados de pequeño para la edad gestacional (PEG) (ORa 1,86, IC 95% 1,38-2,5), FGR < 0,89 (2,89, 2,18-3,83) y score z < -1 (1,81; 1,18-2,76). El riesgo ajustado de mortalidad fue 2,64 (IC 95% 1,71-3,92) para PEG, 3,04 (2,12-4,36) para FGR < 0,89 y 1,37 (0,80-2,32) para score z < -1. CONCLUSIONES: La condición de PEG en los recién nacidos de muy bajo peso (RNMBP) es elevada, siendo muy severa en 1/3. La mayoría de los casos tiene características de simétrico.

Background: By the year 2000, prostate cancer became the second leading cause of cancer death in Chilean men of all ages and is the leading cause of cancer deaths in men of eighty years of age or older. Aim: To analyze the trends in mortality rates from prostate cancer in Chile in a fifty years series, estimating the rate of increase of such rates and their changes in time. Material and methods: A trend analysis for age standardized mortality rates was performed, using join point regression analysis, which allows estimation of the annual percent change of rates and to find significant changes in such trend. Results: Age standardized mortality rates in Chile reached their peak value in 1996, becoming apparently stable from then on. Crude rates have had a steady increase during the whole period. The trends analysis identified three different periods in the growth of the age standardized rates: a first one of slow increase in rates between 1955 and 1981 (0.9% annual increase), a second one of more aggressive growth starting in 1981 (2.6% annual increase), and a third period starting in 1996, in which rates slowly decline at an annual rate of 1%. Conclusions: The tendency of prostate cancer seen in Chile resembles that of industrialized countries, with an increase in its age standardized death rates that suffers a downturn by the end of the past decade. Besides early detection techniques, a substantial part of the reduction in mortality from prostate cancer could be explained by therapeutic improvements (Rev Méd Chile 2004; 132: 579-87).

The type of diet consumed by individuals has been associated with the development of some chronic diseases, including cardiovascular disease (CVD), cancer, diabetes, and others. Populations that consume diets rich in fruits and vegetables and drink wine in moderation, as the Mediterranean, have a higher life expectancy and less chronic diseases than other occidental populations. We carried out an intervention study in humans to evaluate the effect of a Mediterranean diet (MD), an Occidental diet (OD) and their supplementation with red wine, on biochemical, physiological and clinical parameters related to atherosclerosis and other chronic diseases. For 3 months, two groups of 21 male volunteers each, received either a MD or an OD; during the second month, red wine was added isocalorically, 240 ml/day. At days 0, 30, 60 and 90, clinical, physiological and biochemical evaluations were made. In this article we report on the results obtained in plasma fatty acids profile that includes saturated fatty acids (SFA), monounsaturated fatty acids (MUFA), polyunsaturated fatty acids (PUFA), w-6 fatty acids, w-3 fatty acids and w-6/w-3 ratio. Other results have been published previously. Plasma fatty acid percentages in the OD group, compared to the MD group, did not show differences in SFA, but the OD group showed lower levels of MUFA and w-3 fatty acids, and higher levels of PUFA and w-6 fatty acids, with a higher w-6/w-3 ratio than the MD group. Wine supplementation reduced MUFA and increased PUFA in both dietary groups, suggesting that wine could improve a diet with a good w-6/w-3 ratio. Volunteers on MD showed a better fatty acid profile than those on OD, suggesting a lower cardiovascular risk. Moderate consumption of wine improves this profile in the MD group.

Background: Cholelithiasis is the second cause of hospital admissions in Chile. Aim: To study the prevalence of symptomatic gallstone disease and opportunity of cholecystectomy in La Florida, Santiago and among Mapuche Indians in Huapi Island. Patients and methods: In the period 2000-2001, we contacted to 71% (1127 subjects) and to 61% (145 subjects) patients of La Florida and Huapi Island, respectively, that had previously participated in an epidemiological study on cholelithiasis in 1993. We defined symptomatic gallstone patients as those with a history of biliary colic. Each patient was subjected to gallbladder ultrasound. Results: In 1993, 30-35% of gallstone patients were symptomatic (~70% women). During the lapse 1993-2001, only 50% of subjects from La Florida and 25% of patients from Huapi Island were cholecystectomized (p <0.05). Fifty percent of cholecystectomies were emergency operations. In 38 symptomatic Mapuche Indians from Huapi, cholecystectomy was indicated in 2001. After five months of the indication, only one of these subjects had been operated. Laparoscopic cholecystectomy represented 40% of all cholecystectomies performed in the National Health Service Hospitals. Conclusions: This study demonstrates an unacceptable high prevalence of symptomatic gallstone patients remaining non-operated in both the urban and rural communities. This reciprocally correlates with the high frequency of emergency cholecystectomies and the high incidence of gallbladder cancer among Chileans. This study contrasts negatively with the situation of Scotland, where 73.5% of cholecystectomies were laparoscopic in 1998-1999. To reach Scotland standards, the Chilean Public Health System should increase the number of cholecystectomies from 27,000 in 2001 to 57,510 (Rev Méd Chile 2002; 130: 723-30)

Background: The Infectious Systemic Inflammatory Response syndrome and multiple organic dysfunction have common physiopathological mechanisms. Multiple organic dysfunction can be assessed using severity scores. Aim: To relate cytokine kinetics with a multiple organic dysfunction score during sepsis. Material and methods: Tumor necrosis factor a (TNFa) and interleukin 6 (IL6) kinetics were studied in 25 patients with severe sepsis with less than 48 h of evolution and interleukin 1ß (ILß) kinetics was studied in 13 patients. Measurements were made at 0, 12, 24 and 48 hours after admission to the study, using an ELISA technique. These parameters were correlated with the Marshall multiple organic dysfunction score and survival. Results: Mean age of study subjects was 70 years, the APACHE II score was 16.9±6 and the Marshall score was 6.8±3.6. Sepsis was of pulmonary origin in 56% of patients and intra abdominal in 32%. Mortality was 36%. TNFa increased during the study period (24.1 pg/ml initially and 37.8 pg/ml at 24 hours, with a slight posterior reduction, p<0.02). These levels had no association with mortality or organic dysfunction. IL6 remained elevated during the first hours and had a tendency to decrease thereafter. Deceased patients had higher values than survivors (306 pg/ml and 55.4 pg/ml respectively, p=0.011). Its values were tightly correlated with Marshall score, with the number of failing organs, with the presence of shock and with probability of dying during hospitalization. IL1ß remained low and was not associated with clinical parameters. Conclusions: There is a tight correlation between the elevation of IL6 and the severity of the Systemic Inflammatory Response and mortality in these patients with sepsis. (Rev Méd Chile 2001; 129: 347-58)

Background: In the last decades, the number of Universities with medical schools has increased dramatically in our country. Aim: To introduce a conceptual model to estimate the number of physicians that are incorporated to the profession in Chile every year as well as the cumulative number of active physicians in specific time frame. To provide information about the number of available physicians in the country and compare it with the international context. Material and methods: This model includes information about the number of students that are admitted in all medical schools of the country, the dropout rate, the number of immigrant physicians from other countries, and the cumulative number of active physicians in the previous period. Results: There is an increased number of new medical students starting in 1994 that will produce, starting in 2001, a significant increased in the number of new physicians graduated from Chilean Universities. Meanwhile the increased number of new physicians in recent years is mainly explained by a significant increase in immigrant physicians. The number of active physicians estimated by the year 2000 is 18,549 and this number will be 25,704 by the year 2007. With these estimated numbers, we introduce a qualitative model that allowed us to compare the current number of active physicians in Chile with other countries, especially those with a comparable degree of development. This model uses first The Human Development Index and later the per capita income of different countries adjusted by purchasing power in USA. According to these calculations, Chile has a lower number of physicians than similar countries, and this difference will persist, even after the significant increase in the new physicians expected for the new future. Conclusions: Chile continues to have a lower number of physicians than countries with similar human development indices (Rev Méd Chile 2000; 128: 1167-76).

Aceptado en versión corrBackground: Traditionally, medical schools demand their students a high dedication in time, responsibility and integrity. Aim: To assess the predictive capacity of several specific variables, on the academic performance of medical students. Material and methods: All students who entered during 1984-1995 period were studied. The academeic performance was assessed using two indices: an overall evaluation of successfulness as determined by the approval rate in different courses and grade-point average obtained during the first three years at the Medical School. The variables used to predict academic performance were year of enrollment, high school grades, university admission test scores, biomedical and demographic characteristics. All these were meassured at the time when the student was enrolled. Results: Eight hundred and eight students were studied at the end of the third year. The most important predictive variables selected for both performance indices were: high school grades, admission biology test scores, place were high school studies were done, and previous university studies. In addition verbal and mathematics admission academic performance tests scores were selected for grade-point average index. Although, the overall admission score and high school academic performance were significantly associated with the two outcomes, they were not selected in the final models. Conclusions: The best predictors of an optimal academic performance in these medical students were high school grades, admission bilogy test scores, residing in Metropolitan Santiago and previous university studies. (Rev Méd Chile 2000; 128: 671-8).

In some Chilean cities, levels of arsenic (As) in drinking water reached 800 µg/L between 1950 and 1970, while current levels are 40 µg/L. To evaluate the causal role of this exposure in lung and bladder cancers, we conducted a case-control study in Regions I, II, and III of the country. From 1994 to 1996, cases diagnosed as lung cancer and two hospital controls were entered in the study; one control was a patient with a cancer, while the other was a patient without cancer, both conditions unrelated to As. Controls were matched with cases by age and sex. A standard survey containing questions about residence, employment, health history, was administered to study subjects. Data on As concentrations in water were obtained from records of the municipal water companies. A total of 151 lung cancer cases and 419 controls (167 with cancer and 242 without cancer) were enrolled. Median level of lifetime As exposure was significantly higher among cases, with a clear dose-response relationship between mean As exposure levels, with an OR (95% CI) of: 1, 1.7 (0.5-5.1), 3.9 (1.2-13.4), 5.5 (2.2-13.5), and 9.0 (3.6-22) for strata one to five respectively. This study provides new evidence that As in drinking water can cause internal cancers and gives an estimate of the form of this relationship.

En algunas ciudades de Chile, entre 1950 y 1970, los niveles de arsénico (As) en el agua potable alcanzaron los 800 µg/l, estando hoy en 40 µg/l; para evaluar el rol de esta exposición, se llevó a cabo este estudio de casos de cáncer de pulmón y controles en las Regiones I, II y III. Entre 1994 y 1996, se ingresaron casos de cáncer de pulmón y dos controles hospitalarios: un control, un paciente con cáncer y el otro, un paciente sin cáncer, ambos diagnósticos no relacionados con arsénico. Los controles fueron pareados grupalmente por edad y sexo con los casos. A cada sujeto, se le aplicó una encuesta estandarizada sobre residencia, empleo y salud. La información sobre niveles de As en el agua provino de registros de las compañías de agua. Se ingresaron 151 casos de cáncer pulmonar y 419 controles (167 con cáncer y 242 sin cáncer). La mediana de As en el agua potable a lo largo de la vida fue significativamente mayor entre los casos, con una clara relación dosis-respuesta entre el promedio de As y el riesgo, con OR (95% IC) de 1, 1,7 (0,5-5,1), 3,9 (1,2-13,4), 5,5 (2,2-13,5), y 9,0 (3,6-22) para los estratos 1 al 5, respectivamente. Este estudio provee nueva evidencia sobre el rol causal del As en el agua potable en cánceres internos y sobre la forma de la relación entre exposición y riesgo de cáncer.

In some Chilean cities, levels of arsenic (As) in drinking water reached 800 µg/L between 1950 and 1970, while current levels are 40 µg/L. To evaluate the causal role of this exposure in lung and bladder cancers, we conducted a case-control study in Regions I, II, and III of the country. From 1994 to 1996, cases diagnosed as lung cancer and two hospital controls were entered in the study; one control was a patient with a cancer, while the other was a patient without cancer, both conditions unrelated to As. Controls were matched with cases by age and sex. A standard survey containing questions about residence, employment, health history, was administered to study subjects. Data on As concentrations in water were obtained from records of the municipal water companies. A total of 151 lung cancer cases and 419 controls (167 with cancer and 242 without cancer) were enrolled. Median level of lifetime As exposure was significantly higher among cases, with a clear dose-response relationship between mean As exposure levels, with an OR (95% CI) of: 1, 1.7 (0.5-5.1), 3.9 (1.2-13.4), 5.5 (2.2-13.5), and 9.0 (3.6-22) for strata one to five respectively. This study provides new evidence that As in drinking water can cause internal cancers and gives an estimate of the form of this relationship.

En algunas ciudades de Chile, entre 1950 y 1970, los niveles de arsénico (As) en el agua potable alcanzaron los 800 µg/l, estando hoy en 40 µg/l; para evaluar el rol de esta exposición, se llevó a cabo este estudio de casos de cáncer de pulmón y controles en las Regiones I, II y III. Entre 1994 y 1996, se ingresaron casos de cáncer de pulmón y dos controles hospitalarios: un control, un paciente con cáncer y el otro, un paciente sin cáncer, ambos diagnósticos no relacionados con arsénico. Los controles fueron pareados grupalmente por edad y sexo con los casos. A cada sujeto, se le aplicó una encuesta estandarizada sobre residencia, empleo y salud. La información sobre niveles de As en el agua provino de registros de las compañías de agua. Se ingresaron 151 casos de cáncer pulmonar y 419 controles (167 con cáncer y 242 sin cáncer). La mediana de As en el agua potable a lo largo de la vida fue significativamente mayor entre los casos, con una clara relación dosis-respuesta entre el promedio de As y el riesgo, con OR (95% IC) de 1, 1,7 (0,5-5,1), 3,9 (1,2-13,4), 5,5 (2,2-13,5), y 9,0 (3,6-22) para los estratos 1 al 5, respectivamente. Este estudio provee nueva evidencia sobre el rol causal del As en el agua potable en cánceres internos y sobre la forma de la relación entre exposición y riesgo de cáncer.