Ana Maria Baptista Menezes

What are the causal effects of breastfeeding on IQ, obesity and blood pressure? Evidence from comparing high-income with middle-income cohorts

Background A novel approach is explored for improving causal inference in observational studies by comparing cohorts from high-income with low- or middle-income countries (LMIC), where confounding structures differ. This is applied to assessing causal effects of breastfeeding on child blood pressure (BP), body mass index (BMI) and intelligence quotient (IQ). Methods Standardized approaches for assessing the confounding structure of breastfeeding by socio-economic position were applied to the British Avon Longitudinal Study of Parents and Children (ALSPAC) (N ≃ 5000) and Brazilian Pelotas 1993 cohorts (N ≃ 1000). This was used to improve causal inference regarding associations of breastfeeding with child BP, BMI and IQ. Analyses were extended to include results from a meta-analysis of five LMICs (N ≃ 10 000) and compared with a randomized trial of breastfeeding promotion. Findings Although higher socio-economic position was strongly associated with breastfeeding in ALSPAC, there was little such patterning in Pelotas. In ALSPAC, breastfeeding was associated with lower BP, lower BMI and higher IQ, adjusted for confounders, but in the directions expected if due to socioeconomic patterning. In contrast, in Pelotas, breastfeeding was not strongly associated with BP or BMI but was associated with higher IQ. Differences in associations observed between ALSPAC and the LMIC meta-analysis were in line with those observed between ALSPAC and Pelotas, but with robust evidence of heterogeneity detected between ALSPAC and the LMIC meta-analysis associations. Trial data supported the conclusions inferred by the cross-cohort comparisons, which provided evidence for causal effects on IQ but not for BP or BMI. Conclusion While reported associations of breastfeeding with child BP and BMI are likely to reflect residual confounding, breastfeeding may have causal effects on IQ. Comparing associations between populations with differing confounding structures can be used to improve causal inference in observational studies.

Epidemiology of leisure-time physical activity: a population-based study in southern Brazil

We aimed to measure the prevalence of physical inactivity (PI) during leisure time and to identify variables associated with it in a southern Brazilian adult population. A population-based cross-sectional study was carried out, covering a multiple-stage sample of 1,968 subjects aged 20-69 years. Weekly participation in leisure-time physical activity was addressed. For each activity, energy expenditure was calculated using data on duration, metabolic equivalent, and body weight. Energy expenditures of individual activities were summed to give a weekly total. PI was defined as fewer than 1,000 kilocalories per week. The prevalence of PI was 80.7% (95%CI: 78.9-82.4). After adjusted analyses, the following variables were positively associated with the outcome: female gender, age, living with a partner, and smoking. Schooling and economic status were inversely associated with PI. Chronically undernourished individuals were significantly more likely to be inactive. We found no differences according to skin color or alcohol consumption. In conclusion, the prevalence of PI in this adult population was higher than in populations from developed countries, but the associated variables were similar.

Physical activity as a predictor of adolescent body fatness: a systematic review

Adolescent obesity has increased dramatically in several countries in recent decades; however, the contribution of physical activity level to adolescent adiposity requires clarification. This article investigates the effect of physical activity on subsequent levels of adiposity in adolescence. The methodological aspects of the studies included in this article, particularly in terms of measurement accuracy for both exposure (physical activity) and outcome (adiposity) variables, are also evaluated. Systematic searches of the literature were undertaken using online databases, including PubMed/MEDLINE, examination of citations and contacting of authors. The online databases were searched from their earliest records until 2007. Only longitudinal studies with 50 or more adolescents were included. Two independent reviewers assessed the quality of the studies using the Downs and Black checklist. Thirteen observational, five experimental and six quasi-experimental studies (without a control group) were identified. Almost all studies were carried out in high-income settings and showed protective effects of physical activity for both prevention and treatment of adolescent obesity. However, experimental studies undertaken with obese adolescents at baseline usually combined physical activity with dietary changes, making it difficult to assess the effect of physical activity itself on the treatment of obesity. Physical activity estimated from questionnaires and body mass index (BMI) were the most frequently used measures. Despite the feasibility of using these approaches in epidemiological studies, significant limitations are evident. Questionnaires are subjective and adolescents may not report physical activity level accurately. Furthermore, BMI is not an accurate measure of fatness for adolescents, as it is also associated with lean mass, hence bias may arise from its longitudinal association with physical activity level. Despite the majority of studies reviewed showing protective effects of physical activity on adiposity, particularly in individuals who are obese at baseline, the current literature on this issue is sparse and several methodological drawbacks are evident. The main limitations relate to a lack of validity in the measurements of both physical activity and body composition. Further studies are needed in order to generate evidence-based recommendations for the quantity and quality of adolescent physical activity required to prevent or treat adolescent obesity.

Prevalência de hipertensão arterial em adultos e fatores associados: um estudo de base populacional urbana em Pelotas, Rio Grande do Sul, Brasil

OBJECTIVE: To determine hypertension prevalence and its associated risk factors. METHODS: A cross-sectional, population-based study of people ages 20 to 69 living in the urban area of Pelotas, Rio Grande do Sul, Brazil, was conducted. The dependent variable systemic hypertension was defined as blood pressure >160 x 95 mm Hg (average of two readings) or current use of antihypertensive drugs. RESULTS: Among the 1,968 subjects enrolled in the study, hypertension prevalence was 23.6% (95% CI 21.6 to 25.3). A Poisson regression model was used to control confounding factors effects. The following variables remained statistically significant in the final model: family income, age, skin color, gender, family history of hypertension, extra salt intake, and body mass index. CONCLUSION: Compared with a similar study undertaken in 1992, hypertension prevalence increased, particularly in the younger groups.

Prevalence of chronic obstructive pulmonary disease and associated factors: the PLATINO Study in São Paulo, Brazil

Chronic obstructive pulmonary disease (COPD) is now a major public health concern; deaths attributable to COPD in Latin America have increased by 65.0% in the last decade. This study was aimed at evaluating COPD prevalence and associated factors in adults (> 40 years) living in Greater Metropolitan São Paulo, Brazil. The study is part of the Proyecto Latinoamericano de Investigación en Obstrucción Pulmonar (The PLATINO Project), a multi-center survey on COPD burden in Latin America, with São Paulo as the first center where the project has been carried out. A population-based sample was selected in multiple stages. Spirometry tests were performed in each subject pre- and post-bronchodilator and COPD was mainly defined as the ratio of forced expiratory volume to forced vital capacity below 70.0% (fixed ratio definition). Other spirometric criteria were also used for the diagnosis of COPD. COPD prevalence was 15.8% (95%CI: 13.5-18.1) using the fixed ratio definition. COPD was positively associated with age and smoking and inversely with body mass index. Utilization of different COPD spirometry criteria resulted in different percentages of COPD, but similar associated factors.

Fatores de risco para internação por doença respiratória aguda em crianças até um ano de idade

OBJETIVO: Avaliar fatores de risco para hospitalizacao por doenca respiratoria aguda em criancas ate um ano de idade. METODOS: Estudo de casos e controles na cidade de Pelotas, RS. Os casos foram criancas de ate um ano de idade, que se hospitalizaram por doenca respiratoria aguda, de agosto de 1997 a julho de 1998. Os controles foram criancas da comunidade, da mesma idade, sem hospitalizacao previa por essa doenca. Um questionario investigando exposicao a fatores de risco foi aplicado as maes de casos e controles. Os dados foram submetidos a analise univariada, bivariada e multivariada por meio de regressao logistica para avaliacao dos fatores de risco sobre o desfecho de interesse. RESULTADOS: Foram analisadas 777 criancas, sendo 625 casos e 152 controles. Na analise bruta, os fatores de risco associados ao desfecho foram: sexo masculino, faixa etaria menor de seis meses, aglomeracao familiar, escolaridade materna, renda familiar, condicoes habitacionais inadequadas, desmame precoce, tabagismo materno, uso de bico, historia de hospitalizacao e antecedentes de sintomas respiratorios. O trabalho materno foi fator de protecao para internacao por doenca respiratoria aguda. Na analise multivariada, permaneceram associadas: ausencia de ou baixa escolaridade materna (OR=12,5), historia pregressa de sibilância (OR=7,7), desmame precoce (OR=2,3), uso de bico (OR=1,9), mae fumante (OR=1,7), idade abaixo de seis meses (OR=1,7) e sexo masculino (OR=1,5). CONCLUSOES: Os resultados mostraram a importância dos aspectos sociais e comportamentais da familia, assim como morbidade respiratoria anterior da crianca como fatores de risco para hospitalizacao por doenca respiratoria aguda.

Obesidade da população adulta de Pelotas, Rio Grande do Sul, Brasil e associação com nível sócio-econômico

The objectives of this study were to: (1) describe obesity prevalence in a Brazilian city; (2) test the association between obesity and socio-demographic variables; and (3) compare results with a survey in the same city in 1994. A cross-sectional population-based study was carried out in a random sample of 1,968 20-69-year-olds residing in the urban area of Pelotas, Rio Grande do Sul State. Obesity was defined as Body Mass Index (BMI) > 30 kg/m(2). Age and sex-adjusted obesity prevalence was 19.4%. Schooling was not associated with obesity in men. Obesity prevalence was higher in middle-income men. Women with more schooling had lower obesity rates. There was a non-statistically significant reduction in obesity rates compared to a similar study from 1994.

O Mestrado do Programa de Pós-graduação em Epidemiologia da UFPel baseado em consórcio de pesquisa: uma experiência inovadora

O Programa de Pos-graduacao em Epidemiologia da UFPel realizou um intenso trabalho de auto-avaliacao para resolver problemas identificados com seu curso de mestrado. O resultado foi a introducao de uma estrutura curricular baseada em dois pilares. De um lado, disciplinas de cunho teorico, fornecendo a base da formacao do mestrando; de outro, disciplinas de cunho pratico, onde os alunos trabalham coletivamente a construcao de seu projeto de pesquisa, passando pela escolha de um tema, revisao da literatura, definicao de objetivos e da metodologia. Esse esforco conjunto culmina na realizacao de um trabalho de campo unico, na forma de um estudo transversal de base populacional, em que todos os mestrandos participam de maneira integral, obtendo dados para sua dissertacao. Essa estrategia tem garantido a formacao de mestres em epidemiologia com forte base teorica e com experiencia de preparacao e conducao de um trabalho de campo. Alem disso, tem sido possivel manter um tempo de titulacao abaixo de 24 meses. Cerca de 80% dos egressos tem publicado pelo menos um artigo baseado em seu mestrado. Destas publicacoes, quase 90% tem se dado em periodicos classificados como Internacional-A no Qualis da Capes.

Hábitos alimentares de escolares adolescentes de Pelotas, Brasil

OBJETIVO: Descrever a frequencia com que escolares adolescentes de Pelotas (RS) estao seguindo as recomendacoes nacionais para uma alimentacao saudavel. METODOS: Estudo transversal aninhado a um estudo longitudinal em 2004, incluindo adolescentes de 13 e 14 anos matriculados em 32 escolas publicas de Pelotas (RS). A amostra incluiu 2.209 adolescentes. Para avaliacao da frequencia de consumo alimentar, foi utilizado questionario proposto pelo Instituto Nacional do Câncer. Foram construidos desfechos baseados nos dez passos para a alimentacao saudavel propostos pelo Ministerio da Saude do Brasil. RESULTADOS: Os habitos alimentares saudaveis mais frequentes foram o consumo diario de feijao e leite, relatado por cerca de metade dos adolescentes. Quase metade dos jovens referiu ingerir batata frita e salgadinhos no maximo uma vez por semana. Verificou-se consumo adequado de alimentos conservados e enlatados em 44,6% dos adolescentes. Pouco menos da metade dos jovens (43,6%) nunca colocava sal adicional na comida. Quanto ao consumo de doces e outros alimentos ricos em acucar, constatou-se que aproximadamente um terco deles consumia bolos ou biscoitos no maximo duas vezes por semana. CONCLUSAO: Verificou-se baixa frequencia de habitos alimentares saudaveis em todos os subgrupos estudados, sendo a frequencia mais baixa entre jovens de maior nivel socioeconomico e entre as meninas. O habito alimentar que apresentou mais baixa frequencia - 5,3% dos adolescentes - foi o consumo de frutas e verduras cinco ou mais vezes por dia. Politicas publicas de promocao da saude voltadas a melhoria da alimentacao e nutricao dos adolescentes sao necessarias e urgentes.

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.