Maria de Fátima Alves Vieira

Methodological aspects of the 1993 Pelotas (Brazil) birth cohort study

This paper describes the main methodological aspects of a cohort study, with emphasis on its recent phases, which may be relevant to investigators planning to carry out similar studies. In 1993, a population based study was launched in Pelotas, Southern Brazil. All 5,249 newborns delivered in the citys hospitals were enrolled, and sub-samples were visited at the ages of one, three and six months and of one and four years. In 2004-5 it was possible to trace 87.5% of the cohort at the age of 10-12 years. Sub-studies are addressing issues related to oral health, psychological development and mental health, body composition, and ethnography. Birth cohort studies are essential for investigating the early determinants of adult disease and nutritional status, yet few such studies are available from low and middle-income countries where these determinants may differ from those documented in more developed settings.

Long-Lasting Effects of Undernutrition

Undernutrition is one of the most important public health problems, affecting more than 900 million individuals around the World. It is responsible for the highest mortality rate in children and has long-lasting physiologic effects, including an increased susceptibility to fat accumulation mostly in the central region of the body, lower fat oxidation, lower resting and postprandial energy expenditure, insulin resistance in adulthood, hypertension, dyslipidaemia and a reduced capacity for manual work, among other impairments. Marked changes in the function of the autonomic nervous system have been described in undernourished experimental animals. Some of these effects seem to be epigenetic, passing on to the next generation. Undernutrition in children has been linked to poor mental development and school achievement as well as behavioural abnormalities. However, there is still a debate in the literature regarding whether some of these effects are permanent or reversible. Stunted children who had experienced catch-up growth had verbal vocabulary and quantitative test scores that did not differ from children who were not stunted. Children treated before 6 years of age in day-hospitals and who recovered in weight and height have normal body compositions, bone mineral densities and insulin production and sensitivity.

Freqüência de consumo de dietas ricas em gordura e pobres em fibra entre adolescentes

OBJETIVO: Descrever a frequencia e os fatores associados ao consumo de dietas ricas em gordura e pobres em fibra em adolescentes. METODOS: Estudo de delineamento transversal com adolescentes de 10 a 12 anos, realizado em 2004/2005, em Pelotas, RS. A frequencia alimentar no ano anterior a pesquisa foi avaliada pelo questionario de Block, composto por 24 itens alimentares, pontuados de acordo com a frequencia de consumo de alimentos ricos em fibras e gorduras. Na analise bruta, as prevalencias de dietas ricas em gordura e pobres em fibra foram comparadas conforme sub-grupos das variaveis independentes (sexo, cor da pele, nivel socioeconomico, escolaridade materna e estado nutricional do adolescente). Para controle de fatores de confusao, uma analise multivariavel por regressao de Poisson foi realizada para cada desfecho. RESULTADOS: Foram encontrados 4.452 adolescentes, representando 87,5% da coorte original. A maioria dos jovens (83,9%) consumia dieta pobre em fibra, e mais de um terco deles (36,6%) consumia dieta rica em gordura. O nivel socioeconomico e a escolaridade materna mostraram-se diretamente associados com a prevalencia de consumo de dietas ricas em gordura. Jovens dos niveis socioeconomicos A+B e C apresentaram menor frequencia de consumo de dietas pobres em fibra. CONCLUSOES: A prevalencia de dietas ricas em gordura e pobres em fibra foi elevada nessa populacao de adolescentes. Politicas publicas dirigidas aos determinantes dos habitos alimentares sao necessarias e urgentes.

The 11-year follow-up of the 1993 Pelotas (Brazil) birth cohort study: methods

The aim of this study is to describe the methodology of the 2004-2005 follow-up visit of the 1993 Pelotas (Brazil) birth cohort. All children born in Pelotas in 1993 and whose mothers lived in the city at that time were eligible to be enrolled in a longitudinal study. Between July 2004 and March 2005, all cohort participants were sought for a follow-up visit. Several strategies were used to help trace cohort members, including a census of the citys schools and a census of all households in the municipality. The Mortality Information System was monitored in order to identify deaths among cohort members. Of the 5,249 cohort members, 4,452 were interviewed in 2004-5. When added to the 141 deaths, these represent 87.5% of the original cohort. In spite of the logistic and financial difficulties, it is possible to carry out prospective studies with long-term follow-up in the Brazilian context.

Infant feeding and obesity at 11 years: Prospective birth cohort study

OBJECTIVE To evaluate the association between breastfeeding duration, introduction of solid or semi-solid foods before four months of age and overweight/obesity at 11 years. METHODS Prospective population-based birth cohort study, including 1 204 adolescents aged 11 years who were born in Pelotas (Brazil), in 1993, and were previously interviewed at birth, six and 12 months of age. Five explanatory variables were used: duration of any breastfeeding, duration of exclusive or predominant breastfeeding, ever breastfeeding, introduction of solid or semi-solid foods before four months of age, and feeding pattern at four months of age. Risk of overweight was defined as body mass index (BMI) > or = 85(th) percentile, and obesity was defined as BMI > or = 85(th) percentile plus triceps and subscapular skinfolds > or = 90(th) percentile, using the National Center for Health Statistics curves. RESULTS The prevalence of risk of overweight and obesity at 11 years were 23.2% and 11.6%, respectively. The lowest prevalence of both outcomes was found among subjects who were breastfed for one to three months. However, tests for linear trend or heterogeneity did not result in a significant association between breastfeeding indicators and anthropometry at 11 years. Adjustment for sex, skin color, birth weight, maternal schooling, smoking during pregnancy and maternal pre-pregnancy BMI did not alter the findings. CONCLUSIONS Our results do not support the hypothesis that breastfeeding has a long-term lasting effect on anthropometry in this population.

Height and weight gains in a nutrition rehabilitation day-care service

OBJECTIVE To evaluate nutritional recovery patterns in 106 undernourished children assisted by the Center of Nutritional Recovery and Education (CREN, in Portuguese) between January 1995 and December 1999. DESIGN CREN assists undernourished children aged 0 to 72 months living in the southern regions of Sao Paulo, in an outpatient setting. Nutritional status was assessed by Z-scores of weight-for-age, height-for-age and weight-for-height. Nutritional recovery evaluation considered Z-score gains in weight-for-age and height-for-age, grouping into four categories (Z-score increment of 0.50 between groups). Children with birth weight less than 2500 g were classified as low birth weight (LBW), while those born at term and with LBW were classified as small for gestational age. SETTING CREN (Center of Nutritional Recovery and Education in Portuguese), Sao Paulo, Brazil. SUBJECTS One hundred and six children from CREN. RESULTS Among the 106 evaluated children, ninety-eight (92.5 %) recovered their weight or height and seventy-two (67.9 %) recovered both. Nearly half of studied children presented a nutritional recovery (increase in Z-score) of more than 0.50 in height-for-age (46.2 %) and about 40 % in weight-for-age (38.7 %). Multivariate analysis showed that treatment duration and initial weight-for-age contributed to weight-for-age Z-score increment, explaining 25 % of the variation; and treatment duration, initial height-for-age and weight-for-age Z-score increment contributed to height-for-age Z-score increment, explaining 62 % of the variation. CONCLUSIONS Our findings show that nutritional recovery among children who attended CREN was influenced primarily by the degree of nutritional deficit at admission. It has also been shown that biological variables are more important than socio-economic status in determining the rate of nutritional recovery.

Nutritional status of adolescents: the 11-year follow-up of the 1993 Pelotas (Brazil) birth cohort study

We evaluate the influence of demographic, socioeconomic, and maternal variables on the nutritional status of adolescents aged 11 years. We conducted a prospective cohort study including 4,452 adolescents born in Pelotas, Southern Brazil, in 1993, accounting for 87.5% of the original cohort. Nutritional status was evaluated based on World Health Organization criteria. Subjects were classified according to nutritional status into thin, normal, overweight and obese. Independent variables analyzed included skin color, socioeconomic status, maternal schooling, and maternal body mass index (BMI). Analyses were stratified by sex, and multivariable regression was performed using the multinomial logistic approach. Overall, 7% of adolescents were classified as thin, 11.6% as overweight, and 11.6% as obese. Among boys, thinness was inversely associated with maternal schooling and maternal BMI. Among girls, thinness was directly associated with maternal BMI. Overweight and obesity were directly associated with socioeconomic status and maternal BMI, the former showing the strongest association with nutritional status among adolescents.

Consumo alimentar entre crianças brasileiras de dois a cinco anos de idade: Pesquisa Nacional de Demografia e Saúde (PNDS), 2006

O objetivo deste estudo foi analisar a mortalidade por doencas circulatorias paralelamente a evolucao da Estrategia Saude da Familia no Brasil. Estudo ecologico, retrospectivo, baseado na evolucao temporal da ESF e nas taxas de mortalidade por doencas circulatorias no Brasil. Foi realizada uma descricao da razao de cobertura habitante x ESF e dos indicadores de saude relacionados a mortalidade por doencas circulatorias. Para a associacao estatistica utilizou-se o teste de Correlacao de Spearman. Houve aumento populacional no Brasil em 15%, evolucao de 761% no numero de ESF e 5% de aumento na mortalidade por doencas circulatorias. A razao populacao x ESF passou de 52.838 (1998) para 7.084 (2006) pessoas assistidas por ESF. As regioes norte e nordeste apresentaram crescimento nas taxas de mortalidade por doencas circulatorias e em 21 (81%) estados houve correlacao positiva entre mortalidade por doencas circulatorias e ESF (r: > 0,7; p < 0,01). Por fim, considera-se a ESF uma importante politica publica de saude, tendo obtido resultados exitosos no Brasil desde a sua implementacao. Entretanto, em um contexto geral, sua expansao nao influenciou a reducao da mortalidade por doencas circulatorias, tendo apresentado aumento deste indicador no pais.

Diagnosis of overweight and obesity in adolescents from the 1993 Pelotas Birth Cohort Study, Rio Grande do Sul State, Brazil: comparison of two diagnostic criteria

Various cut-off points for body mass index have been proposed to assess nutritional status in adolescents. The aim of this study was to compare two methods for evaluating overweight and obesity. In 2004-5, 4,452 adolescents from the 1993 Pelotas (Brazil) birth cohort study were evaluated, representing 87.5% of the original cohort. Overweight and obesity were evaluated using the methods proposed by the World Health Organization (WHO) and International Obesity Task Force (IOTF). Prevalence of overweight was similar when comparing the two methods (WHO: 23.2%; IOTF: 21.6%). Prevalence of obesity was higher according to the WHO criterion (total sample: 11.6%; boys: 15.1%; girls: 8.2%) as compared to IOTF (total sample: 5.0%; boys: 5.6%; girls: 4.4%). The kappa statistic was around 0.9 for determining overweight and 0.4 for obesity. The IOTF classification showed high specificity in comparison to the WHO criterion for determining overweight and obesity. However, sensitivity was high for overweight but low for obesity. Our data show that the IOTF classification underestimates the prevalence of obesity in early adolescence.

Intake of fat and fiber-rich foods according to socioeconomic status: the 11-year follow-up of the 1993 Pelotas (Brazil) birth cohort study

This study describes the food intake of adolescents participating in the 1993 birth cohort from Pelotas, Southern Brazil, according to socioeconomic position. We carried out a cross-sectional analysis of data collected in the 2004-2005 follow-up visit. Food intake in the previous year was evaluated using the Block questionnaire. Socioeconomic status was evaluated based on an assets index, divided into quintiles. Foods with the highest frequency of daily intake were white bread (83%), butter or margarine (74.6%), beans (66.4%) and milk (48.5%). Intake of butter or margarine, bread, and beans was more frequent among poorer adolescents, and the inverse was true for milk. Intake of fruits and vegetables was low in all socioeconomic strata, but particularly low among the poor. In early adolescence, all socioeconomic groups showed high consumption of foods rich in fat and low consumption of foods rich in fiber.