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.

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.