Identification of dietary patterns by principal component analysis in schoolchildren in the South of Brazil and associated factors

Abstract Objectives: to identify dietary patterns (DP) and associated factors in first grade school-children in elementary schools in the South of Brazil. Methods: school-based cross-sectional study, with a non-probabilistic sample of 782 schoolchildren aged 6 to 8. Food intake was assessed by a food frequency questionnaire. DP were identified using the principal component analysis and the prevalence ratios were obtained by Poisson regression with a robust variance. Results: four DP were identified and accounted for 25.3% of the total variance: "fruit, vegetables and fish" (8.5%), "sweets and salty snacks" (7.0%), "dairy, ham and biscuits" (5.0%) and "common Brazilian food" (4.8%). After the adjustment, breakfast habit and lower frequency of meals in front of a screen increased the probability of adherence to a high consumption of DP of "fruit, vegetables and fish". The maternal schooling level was linearly and inversely associated with DP of "sweets and salty snacks" and "common Brazilian food", and positively related to the DP of "dairy, ham and biscuits". Schoolchildren with food inse-curity and sufficiently active had higher probability of adherence to DP of "common Brazilian food". Conclusions: four DP were identified and associated with food insecurity, maternal socioeconomic characteristics and schoolchildren’s behavioral characteristics.

Prevalence and risk factors for chronic obstructive pulmonary disease according to symptoms and spirometry

The burden of COPD is quite high and its prevalence is increasing. Few data are available from Latin America. There is no consensus on what criteria should be the gold standard for the definition of this disease. A population-based study was carried out in a southern Brazilian city, including adults aged 40-69 years. The aim was to measure the prevalence of COPD according to several criteria. From the 1,046 subjects chosen from a multiple-stage sampling protocol, a sub-sample of 234 subjects was systematically selected to undergo spirometry. Percentages of COPD according to different criteria were: chronic bronchitis by questionnaire (7.8%); GOLD stage 0 (7.3%); fixed ratio (15.2%); GOLD stage II (9.9%); ERS (27.7%). The relationship among the three lung functional measurements showed that around 70% of all subjects had negative results with all three criteria, and around 10% were positive according to all three. Utilization of symptom-based or spirometry definitions of COPD provide different prevalence estimates. Use of different spirometric criteria also resulted in different percentages of COPD. According to spirometry, COPD was higher among men, elderly, those with low education and ex-smokers. On the other hand, current smokers were more likely to present symptoms of chronic bronchitis. The fixed ratio criterion is recommended when population-specific reference curves are not available, while the GOLD definition is recommended to evaluate severity of COPD.

[Determinants of malnutrition in a low-income population: hierarchical analytical model]

To investigate the determinants of malnutrition among low-income children, the effects of socioeconomic, environmental, reproductive, morbidity, child care, birthweight and breastfeeding variables on stunting and wasting were studied. All 354 children below two years of age living in two urban slum areas of Pelotas, southern Brazil, were included. The multivariate analyses took into account the hierarchical structure of the risk factors for each type of deficit. Variables selected as significant on a given level of the model were considered as risk factors, even if their statistical significance was subsequently lost when hierarchically inferior variables were included. The final model for stunting included the variables education and presence of the father, maternal education and employment, birthweight and age. For wasting, the variables selected were the number of household appliances, birth interval, housing conditions, borough, birthweight, age, gender and previous hospitalizations.

[Race and inequality among women: an example in southern Brazil]

This study uses epidemiological data to investigate socioeconomic proportions of distinctions raised by "racism" in Brazilian society. A population-based cross-sectional study was conducted with a sample of 2,779 women ages 14 through 49, living in a southern Brazilian city. Black and mixed-race women had less schooling, lower family income, and worse housing conditions than white women. They also used contraceptive methods less frequently, had more children, and had higher spontaneous abortion and stillbirth rates than white women. Virtually all of the results show a linear relationship between such categories, i.e., the "darker" the woman's skin color, the worse her socioeconomic and reproductive conditions. We also observed that black women were either separated, divorced, or widowed, another apparent factor for black women's impoverishment, related mainly to their limited employment opportunities. The results of the current study indicate that racial relations among women are an issue that should foster a discussion concerning citizenship in Brazil.

[Reproductive characteristics of women from 15 to 49 years of age: comparative studies and planning for actions]

INTRODUCTION

The availability of socioeconomic, demographic and reproductive health data about women at national, regional and municipal levels allows comparisons between regions and may offer background information for planning actions of the Program of Integrated Assistance for Women's Health.

METHODS

A population-based cross-sectional study was carried out in Southern Brazil. Three thousand and two women aged 15 to 49 years living in an urban area in Pelotas, were selected for inclusion in the study. A structured questionnaire was used to collect the socioeconomic, demographic and reproductive characteristics. The analysis included comparison of means and proportions. In the sterilization analysis the data were controlled for age.

RESULTS

Nearly 56% of the women were married/in union and 35% were single. A third of them were housewives and 50% were wage workers. The mean of schooling was 8.5 years. Almost, half of the adolescents (15 to 19 years old) have an active sexual life, and of those 33% had already been pregnant. A high percentage of unwanted pregnancy was reported, mainly among younger women. Near the end of their reproductive life (women aged 45 to 49 years) the mean of children per woman was 2.4. The most prevalent methods were pill and sterilization. Among married women or those living in consensual union, 15% had been sterilized. The sterilization rate increased with age and attained nearly 25% of women aged over 35 years; 29.6% of sterilized women had had a stillborn child and 18.3% a pre-term baby; 20% of husbands/partners did not accept the use of any contraceptive method.

CONCLUSIONS

The study results confirm the need for additional attention to and development of special programs for adolescents, improvements in the access to services, increase in the use of the contraceptive options already available and research and programatic actions related to the theme "men/reproductive health.

[Prevalence and risk factors of obesity in adults]

INTRODUCTION

A population-based cross-sectional study was conducted in Pelotas, Southern Brazil, with the objective of determining the prevalence of obesity and identify associated, variables as this condition increased markedly in the country between 1974 and 1989.

MATERIAL AND METHODS

One thousand and thirty-five adults between 20 and 69 years of age were studied. Obesity was defined as a Body Mass Index--BMI--equal to or over 30 Kg/square meter). The multivariate analyses took into account the hierarchical model of the variables associated with obesity for both men and women.

RESULTS

The prevalence for the overall population was of 21% (CI 18-23). It was higher among women--25% (CI 22-29) than for men--15% (CI 12-18). Socioeconomic status was positively associated with obesity among men, whereas the opposite situation was reported for women, with those belonging to the poorest social strata presenting increased BMI. Reported obesity in their parents was associated with increased BMI in the subjects, and this association remained statistically significant even after compensating for the effect of possible confounding variables. Self-reported diabetes and arterial hypertension doubled the risk of obesity, whereas non-smoking was associated with obesity only among women. Variables which were not associated with obesity after adjusting for confounders were alcohol consumption, marital status and parity. Women having more daily meals were less prone to obesity, even after controlling for confounders, and this association was not quite significant for men (p = 0.07).

CONCLUSIONS

The prevalence of obesity was higher among women, and important differences in risk factors were noticed when the population was considered by sex.

Pacifier use and short breastfeeding duration: cause, consequence, or coincidence?

OBJECTIVES

Pacifiers are related to a shorter duration of breastfeeding. However, it is unclear whether this association is causal, because confounding, reverse causality, and self-selection of mothers may play a role. These issues were investigated through a combination of epidemiologic and ethnographic research in southern Brazil.

METHODOLOGY

A population-based cohort of 650 mothers and infants were visited shortly after delivery and at 1, 3, and 6 months. The rate of complete follow-up was 96.8%. A subsample of 80 mothers and infants was selected for the ethnographic study, which included in-depth interviews and participant observations in the age range of 2 to 6 months with a mean of 4.5 visits.

RESULTS

The epidemiologic study showed that pacifier use was common with 85% of users at 1 month. However, this was a dynamic process, with many infants starting or abandoning the pacifiers in any age range. Children who stopped breastfeeding in a given period were likely to take up the pacifier during that period. Further analyses excluded all infants not breastfed at 1 month of age and those who reportedly had breastfeeding problems, leaving 450 infants with full data. Intense pacifier users at 1 month (children who used the pacifiers during most of the day and at least until falling asleep) were four times more likely to stop breastfeeding by 6 months of age than nonusers. Users also had fewer daily breastfeedings than nonusers. After adjustment for several confounding variables, logistic regression showed that pacifier use was still associated with an odds ratio of 2.5 (95% confidence interval, 1.40 to 4.01) for stopping breastfeeding. The ethnographic analysis showed that pacifier use was widely regarded as a positive behavior and that mothers often strongly stimulated the infants to accept it. Although few mothers openly admitted that pacifiers might shorten breastfeeding, a considerable group effectively used pacifiers to get their infants off the breast or to increase the interval between feedings. The latter also had rigid breastfeeding styles that increased maternal-infant distance, had important concerns about objective aspects of infant growth and development, and were highly sensitive to infant crying. These behaviors were linked to intense comparison between themselves and other mothers and to a lack of self-confidence. Nonwhite mothers, those who delivered vaginally, and mothers of infant girls seemed to be more confident and less affected by these difficulties. The epidemiologic analysis confirmed that pacifier use was more closely associated with breastfeeding duration among nonwhite mothers and for normally delivered infants.

CONCLUSIONS

Pacifiers may be an effective weaning mechanism used by mothers who have explicit or implicit difficulties in breastfeeding, but they are much less likely to affect infants whose mothers are confident about nursing. Breastfeeding promotion campaigns aimed specifically at reducing pacifier use will fail unless they also help women face the challenges of nursing and address their anxieties. The combination of epidemiologic and ethnographic methods was essential for understanding the complex relations between pacifier use and breastfeeding.

The role of conceptual frameworks in epidemiological analysis: a hierarchical approach

BACKGROUND

This paper discusses appropriate strategies for multivariate data analysis in epidemiological studies.

METHODS

In studies where determinants of disease are sought, it is suggested that the complex hierarchical inter-relationships between these determinants are best managed through the use of conceptual frameworks. Failure to take these aspects into consideration is common in the epidemiological literature and leads to underestimation of the effects of distal determinants.

RESULTS

An example of this analytical approach, which is not based purely on statistical associations, is given for assessing determinants of mortality due to diarrhoea in children.

CONCLUSIONS

Conceptual frameworks provide guidance for the use of multivariate techniques and aid the interpretation of their results in the light of social and biological knowledge.

Falling diarrhoea mortality in Northeastern Brazil: did ORT play a role?

The impact of oral rehydration therapy (ORT) on the recent decline in diarrhoea mortality in the northeast of Brazil was studied. Proportionate infant mortality fell from 32% in 1980 to 17% in 1989 and infant deaths attributed to diarrhoea dropped from 41% to 25%, resulting in an overall reduction of 57%. Similar decreases were observed for children aged 1-4 years. Diarrhoea admissions also fell from 57% of infant hospitalizations in 1980 to 30% in 1990. None of the other major causes of death or admissions showed such decline. ORT was introduced in the early 1980s, being used in 35% of all episodes in 1991 and in 62% of those regarded as severe by the mother. Other changes included a worsening of socioeconomic conditions and increases in water supply, vaccine coverage, breastfeeding duration and nutritional status. A simulation model estimated that changes in factors other than ORT would lead to a 21% reduction in infant diarrhoea mortality, or about one-third of the actual decline. Finally, an ecological analysis showed that ORT use rates were inversely correlated to infant diarrhoea mortality (r=-0.61; p=0.04). Despite the shortcomings of the available data, these findings suggest an important impact of ORT on diarrhoea mortality.

[Longitudinal study of the mother and child population in an urban region of southern Brazil, 1993: methodological aspects and preliminary results]

All babies born in the hospitals of the city of Pelotas, Brazil, in 1982 were studied soon after delivery and followed up prospectively during the first years of their lives. In 1993, this study was repeated with a similar methodology, with the aim of assessing eventual changes in the level of maternal and child health. All five maternity hospitals in the city were visited daily and the 5,304 babies born included in the study. They were weighed and measured, and their gestational age was assessed using the Dubowitz method. Their mothers were examined and interviewed regarding a large number of risk factors. The mortality of these children was studied through the surveillance of all hospitals, cemeteries and death registries, and all hospital admissions were also recorded. Two nested case-control studies were carried out to assess risk factors for mortality and hospital morbidity. A systematic sample of 655 children were examined at home at one and three months of age, and these infants, as well as another sample of 805 children including all low-birthweight babies were also examined at the ages of six and twelve months. Their psychomotor development was also assessed. Losses to follow-up were only 6.6% at twelve months. Relative to the 1982 indicators, perinatal mortality fell by about 30% and infant mortality by almost 50%. The median duration of breastfeeding increased from 3.1 to 4.0 months. On the other hand, there was little change in the prevalences of low birthweight or of length for age at twelve months. The article that refers this abstract describes the methodology of the study and forthcoming publications will present detailed results.

Tendências e diferenciais na saúde materno-infantil: delineamento e metodologia das coortes de 1982 e 1993 de mães e crianças de Pelotas, Rio Grande do Sul

Mudanças ocorridas na última década em termos econômicos e assistenciais podem haver afetado a saúde materno-infantil. Dois estudos foram realizados em Pelotas, Rio Grande do Sul. As coortes de mães e recém-nascidos nos anos de 1982 e 1993 foram estudadas desde o nascimento. As mães foram identificadas nos hospitais-maternidade e responderam a um questionário padronizado, sendo seus filhos examinados. Mais de 99% dos recém-nascidos foram incluídos nas coortes, totalizando 5.914 nascidos vivos em 1982 e 5.249 em 1993. A mortalidade das crianças foi monitorizada, e em 1993 as hospitalizações também o foram. Em 1982, tentou-se localizar cerca de 25% das crianças aos 12 meses de idade e todas com a idade média de vinte meses. Foi possível encontrar cerca de 82% das crianças aos 12 meses e, graças a uma mudança de estratégia, 87% aos vinte meses. Em 1993, tentou-se acompanhar 20% das crianças e mais todos os recém-nascidos de baixo peso aos 12 meses de idade, sendo 95% localizados. Este artigo descreve os principais aspectos metodológicos de ambos os estudos, cujos principais resultados estão incluídos nos próximos artigos desse suplemento.

Saúde materno-infantil em Pelotas, Rio Grande do Sul, Brasil: principais conclusões da comparação dos estudos das coortes de 1982 e 1993

Este artigo resume os principais achados dos estudos das coortes materno-infantis de Pelotas em 1982 e 1993. Houve uma redução no número de nascimentos, de 6.011 em 1982 para 5.304 em 1993, fato não distribuído de forma eqüitativa entre os diferentes grupos de renda familiar, ocorrendo entre as mulheres de baixa renda cerca de 1.000 nascimentos a menos do que em 1982. O grupo com renda mais elevada contribuiu com um aumento de cerca de 300 nascimentos. A situação nutricional das mães apresentou variações na década, com um aumento médio de 3,5 cm em estatura e 3,9 kg no peso no início da gestação. Apesar destas melhoras, a proporção de recém-nascidos de baixo peso aumentou para 9,8% em 1993 (9,0%, 1982). Observou-se um aumento na incidência de nascimentos pré-termo e de retardo de crescimento intra-uterino assim como uma redução nos coeficientes de mortalidade perinatal - 32,2/1.000 em 1982 e 22,1/1.000 em 1993. A situação nutricional aos 12 meses de idade apresentou comportamentos distintos, com um discreto aumento do déficit de comprimento/idade em 1993, e uma redução de quase 50% nos déficits de peso/idade e peso/comprimento. O coeficiente de mortalidade infantil decresceu de 36,4 /1.000 nascidos vivos em 1982 para 21,1/.000 em 1993.

Twenty-four-hour recall overestimates the dietary intake of malnourished children

Food intake and morbidity are the two main proximal determinants of childhood malnutrition. Intake is usually assessed through the 24-h recall method. Few studies, however, have evaluated the accuracy of this method; in particular, it is not known whether accuracy varies according to the child's nutritional status. The intake of 50 children (< 2 y old), of whom 25 were underweight (weight-for-age more than 2 SD below the National Center for Health Statistics reference), as evaluated through weighing of all foods (gold standard) and through recall. The overall intakes of energy, fat and protein were significantly greater according to the recall method than by weighing. The trend towards overestimation was more marked for malnourished children than for well-nourished children. The possibility of such bias should be taken into account in future studies.

[The use of pacifiers in children: fecal contamination and association with diarrhea]

A cross-sectional study of 354 children under two years of age was carried out in two periurban slums, with poor sanitary and socioeconomic conditions, located in Pelotas, southern Brazil. Most (79%) of the children studied were current users of pacifiers, 15% had never used one and the remaining 6% were ex-users. Among current users, 38% sucked a pacifier most of the time ("constant users"). Of the pacifiers in constant use, 93% were cultured for evidence of fecal contamination. Fecal coliforms were present in 49% of these. Diarrhoea was reported in 35% of all the children in the two weeks preceding the survey. Among constant pacifiers users, 40% had had diarrhoea in the preceding fortnight; this proportion was 32% for occasional users and 37% for non-users. These differences were not statistically significant.

Use of pacifiers and breastfeeding duration

Pacifiers are widely used in many developing countries. Although their use is not recommended for breastfeeding infants, there have been no published reports on the association between pacifier use and risk of early weaning. In a study of 354 infants in Brazil, mothers were asked about pacifier use at age 1 month, duration of breastfeeding, and introduction of other foods. Among 249 children still breastfed at 1 month, the risk that a child would be weaned at any age between 1 and 24 months was higher in pacifier users than in non-users (hazard ratio 3.0, 95% CI 2.0-4.6). The association remained even after adjustment for the child's age, sex, birthweight, socioeconomic status, and age at introduction of bottle-feeding.