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Biomedical subjects

C G Victora

Publications and source records attributed to C G Victora.

At least 73 records · Page 4Linked to original sources
PubMed1997

Low birthweight, preterm births and intrauterine growth retardation in relation to maternal smoking.

The association between the intensity and duration of cigarette smoking during pregnancy and the frequency of low birthweight, preterm births and intrauterine growth retardation was investigated in a historical cohort. All 5166 livebirths occurring in the city of Pelotas, Brazil, during 1993 were identified and mothers interviewed soon after delivery. Children whose mothers smoked during pregnancy had a birthweight 142 g lower than those of non-smoking mothers. The odds ratio for low birthweight among children of smokers was 1.59 [95% CI 1.30-1.95]. There was no association between smoking and preterm delivery assessed by the Dubowitz score. In relation to intrauterine growth retardation, smoking was associated with an odds ratio of 2.07 [95% CI 1.69-2.53]. There was a direct dose-response association between the number of cigarettes smoked and the risk of growth retardation. Women whose partner smoked were also at higher risk of having a child with growth retardation. All the above results were adjusted for confounding factors. The effect of maternal smoking on low birthweight seems to be attributable to intrauterine growth retardation rather than preterm delivery.

Analysis of Variance↗
PubMed1997

Breast feeding, pacifier use and infant development at 12 months of age: a birth cohort study in Brazil.

Many studies suggest that breast feeding confers developmental and intellectual advantages on children. In a recent study, however, no association was found between breast feeding and intelligence in adult life after adjustment for other variables, and the use of pacifier in infancy was the most important predictor of intelligence. We analysed the associations between breast-feeding duration, pacifier use and suspected developmental delay at 12 months of age in a birth cohort in Pelotas, southern Brazil. All 5304 hospital births occurring during 1993 were studied and a sample was followed up at 1, 3, 6 and 12 months of age. Breast-feeding practices and use of pacifiers were assessed at each visit, as well as suspected developmental delay, measured by the Denver II test. The prevalence of developmental delay was analysed, through logistic regression, according to breast-feeding status and pacifier use, accounting for the possible confounding effect of other variables. The prevalence of suspected developmental delay at 12 months was 34.1%, being slightly higher among children who used pacifiers at 6 months than among non-users (35.3% and 28.7% respectively). There was a marked negative association between breast-feeding duration and developmental delay, with children breast fed for 9 months or more presenting significantly less suspected developmental delay (25.5%) than those breast fed for less than 1 month (42.4%). The effects of multiple variables were tested, and only high parity, smoking during pregnancy, birthweight, gestational age, pacifier use and breast-feeding duration remained significantly associated with suspected developmental delay. The effect of pacifier use, however, disappeared after adjusting for breast-feeding duration, suggesting that breast feeding, and not pacifiers, affects child development.

Age Factors↗
PubMed1997

Issues in the design and interpretation of studies to evaluate the impact of community-based interventions.

Increasingly, epidemiologists are faced with the need to evaluate the impact of an intervention that is delivered at the level of a community or cluster of individuals, rather than at the individual level. This has profound implications for the design and interpretation of a study to evaluate its impact. We start by discussing the issues arising in the extension of the randomized double-blind controlled trial methodology to the evaluation of interventions delivered to clusters of individuals, or to whole communities, where the unit of randomization is a cluster of individuals rather than an individual. We then consider alternative approaches to design, discuss their relative strengths and weaknesses and present a framework of design options. Finally we propose a pragmatic approach to evaluation design in this setting. We believe that the answer lies in the judicious selection of different design elements, combined in such a way that when the evidence from each is presented together, a clear picture of the impact of the intervention emerges. We illustrate this using an example from the recent literature.

Community Medicine↗
PubMed1997

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.

Child↗
PubMed1997

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.

Bottle Feeding↗
PubMed1997

[Hospitalization due to pneumonia: the influence of socioeconomic and pregnancy factors in a cohort of children in Southern Brazil].

OBJECTIVE: To investigate the influence of socioeconomic and gestational factors on admission due to pneumonia in the post-neonatal period. METHODOLOGY: Cohort. Children born in the city Pelotas, Brazil, in 1993. Cases were children admitted to hospital for 24 hours or more, between the ages of 28 and 364 days, with a diagnosis of pneumonia. RESULTS: Of the 5,304 children in the cohort, 152 (2.9%) were hospitalized with pneumonia. The positive predictive value of the clinical diagnosis compared to the radiological assessment was 76%. Analysis by conditional logistic regression showed that social class and maternal schooling were strongly inversely associated with pneumonia Children of adolescent mothers were twice as likely to be admitted. The relative risk for children whose mothers were of parity three or greater was 2.8 relative to primiparae. Maternal weight gain during pregnancy of less than 10 kg was associated with a 40% increase in risk. CONCLUSION: Socioeconomic factors were important determinants of pneumonia admissions. Maternal age, parity and weight gain were also significant risk factors.

Brazil↗
PubMed1997

Land tenure and child health in Rio Grande do Sul: the relationship between agricultural production, malnutrition and mortality.

"Four different approaches were applied to test the hypothesis that patterns of land tenure and agricultural production in Rio Grande do Sul [Brazil] are important infant mortality determinants. These studies have employed various data sources on distinct analytical levels.... The results...provide reliable evidence of there being a strong relationship between the degree of concentration of land tenure and agricultural production on the one hand, and malnutrition and infant mortality on the other."

Agriculture↗
PubMed1997

Low body weight: a simple indicator of the risk of dehydration among children with diarrhoea.

The early identification of children at high risk of dehydration as a consequence of diarrhoea would be of great value for health care workers in developing countries. By comparing children aged less than two years with diarrhoea and moderate to severe dehydration with matched controls who had uncomplicated diarrhoea, a number of prognostic factors were assessed. Low body weight, regardless of age, was strongly associated with the risk of dehydration; using 7.0 kg as a cut-off, it had a sensitivity of 75% and a specificity of 68%. Low body weight was superior to more complex anthropometric indices, including weight for age, weight for length or length for age, and also to early signs and symptoms during the episode. By reflecting the effects of both young age and those of malnutrition, low body weight may prove to be a simple indicator for predicting dehydration among children with diarrhoea presenting at a health service.

Body Weight↗
PubMed1997

[Tobacco smoking among pregnant women in an urban area in southern Brazil, 1982-93].

OBJECTIVE: A comparison between on the prevalence of smoking during pregnancy in 1982 and that in 1993 in Pelotas, Southern Brazil. METHODOLOGY: Cross-sectional study. All hospital deliveries in 1982 and 1993--corresponding to over 99% of all births in those years--were studied. A total of 6,011 and 5,304 mothers were interviewed, respectively. RESULTS: The prevalence of smoking during pregnancy showed a small decrease from 35.7% in 1982 to 33.5% in 1993 (p < 0.05). In the two years under study, family income and number of antenatal care visits were inversely associated with the prevalence of maternal smoking. The rate of stopping smoking during pregnancy was 20.6%.

Adult↗
PubMed1996

Case-control study of risk of dehydrating diarrhoea in infants in vulnerable period after full weaning.

OBJECTIVES: To investigate risk factors for dehydrating diarrhoea in infants, with special interest in the weaning period. DESIGN: Case-control study. SETTING: Metropolitan area of Porto Alegre, Brazil. SUBJECTS: Cases were 192 children aged 0-23 months hospitalised with acute diarrhoea and moderate to severe dehydration. Controls were 192 children matched for age and neighbourhood who did not have diarrhoea in the previous week. MAIN OUTCOME MEASURES: Associations between dehydrating diarrhoea and child's age, type of milk consumed, time since breast feeding stopped, and breast feeding status. RESULTS: In infants aged < 12 months the risk of dehydrating diarrhoea was significantly higher in the first 9 months of life (P < 0.001), and in those aged 12-23 months the risk was again greater in younger children (12-17 months) (P = 0.03). The type of milk consumed before start of diarrhoea episode was strongly associated with dehydration independent of socioeconomic, environmental, maternal reproductive, demographic, and health services factors. Compared with infants exclusively breast fed, bottle fed infants were at higher risk (odds ratio (95% confidence interval) for cow's milk 6.0 (1.8 to 19.8), for formula milk 6.9 (1.4 to 33.3)). Compared with those still breast feeding, children who stopped in the previous two months were more likely to develop dehydrating diarrhoea (odds ratio 8.4 (2.4 to 29.6)). This risk decreased with time since breast feeding stopped. CONCLUSION: These results confirm the protective effect of breast feeding and suggest there is a vulnerable period soon after breast feeding is stopped, which may be of relevance for developing preventive strategies.

Acute Disease↗
PubMed1996

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.

Brazil↗
PubMed1996

Reliability of environmental, biological and health characteristics of infants from a developing country.

BACKGROUND: Although most epidemiological data are gathered by interviews, few studies ascertain their reliability. This study quantified inter-observer reliability of environmental, biological and health characteristics of underprivileged children, in a southern Brazilian state. METHODS: Five health care professionals who had received extensive standardized interview and observation training interviewed mothers and observed the home environments of a random sample of 102 children. A second interview was conducted by a sixth health professional who had received separate but identical training without the initial interviewer knowing a follow-up interview would be conducted. Data from the two independent interviews and observations were compared for agreement using the kappa statistic. RESULTS: There was excellent agreement (kappa > 0.75) for most of the household characteristics, such as type of walls, ceiling, floor and windows in spite of the diversity of buildings. Presence of the parents, number of people in the house-hold, age of the mother and health assistance were reliable as well. However, information about skin colour of the mother and the number of cracks in the house only reached fair agreement. CONCLUSIONS: These results showed that data gathered by observation and interviews generate accurate information about environmental, biological and health care characteristics. Those based on written information, such as birth date, were highly concordant.

Adolescent↗
PubMed1996

Abdominal circumference contributes to absence of wasting in Brazilian children.

A number of population groups in Latin America show high prevalences of stunting (low height-for-age) despite very low rates of wasting (weight-for-height deficits). One possible explanation for this phenomenon is an increase in abdominal circumference, which would affect children's weights but not their heights. This study was designed to describe the abdominal circumferences of a group of poor children from Northeast Brazil, and to relate these to their weight-for-weight z-score. Children (n = 252) participating in a government growth monitoring program were studied. The prevalence of stunting (below -2 SD) was 26.2%, but only 1.2% were wasted. Abdominal circumferences increased with age up to 36 mo, followed by a slight decline after 48 mo. Abdominal circumference was the anthropometric measurement most closely associated with weight-for-height, with a coefficient of determination of 41%. Even after adjusting for arm circumference, abdominal circumference continued to explain 16% of the variation in weight-for-height. Despite slight differences in measurement techniques, the study children had consistently larger abdominal girths than a sample of North American children. These findings must be verified by replication but highlight a possible contribution of abdominal circumference in the determination of levels of wasting.

Abdomen↗
PubMed1996

Alcoholic beverage consumption and associated factors in Porto Alegre, a southern Brazilian city: a population-based survey.

OBJECTIVE: To describe the pattern of alcoholic beverage consumption and the prevalence of at risk drinking behaviors, as well as their association with demographic and socioeconomic factors in the adult population of Porto Alegre, a southern Brazilian city. METHOD: In a cross-sectional, population-based, multistage random sampling study, 1,091 (600 female) individuals (92% of those eligible) were selected and interviewed at home. Exposure to alcohol was measured by the CAGE questionnaire and by inquiring about the type, quantity and frequency of alcoholic beverage consumption. An average consumption of 30 g per day or more, a level of exposure associated with health risks, was considered as heavy drinking. Two positive answers to the GAGE questionnaire represented the cutoff for indicating dependence. RESULTS: The prevalences were: 9.3% (95% CI: 7.6 to 11.0) for dependence, 15.5% (13.4 to 17.7) for heavy drinking and 12.3% (10.4 to 14.2) for daily drinking; 24.1% (21.7 to 26.6) were abstinent. Women consumed alcoholic beverages in lower frequency and amounts than men. The most widely consumed beverages were beer, wine and "cachaça," a Brazilian sugarcane spirit. In a logistic regression model, increasing age, lower education and income, and nonwhite race were associated with heavy drinking and dependence. Households with 3-4 persons were associated with the lowest risk of heavy drinking, but the prevalence of dependence was higher in crowded households. The presence of another heavy drinker or dependent in the household was associated with heavy drinking but not with dependence. CONCLUSIONS: The study characterized a detailed pattern of alcoholic beverage use and indicated that at risk drinking is an important public health problem in a developing country. The risk factors for heavy drinking and dependence were the same, with the exception of age at starting to drink, heavy drinking or dependence-positive household members.

Adult↗
PubMed1996

[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.

Birth Weight↗
PubMed1996

[Hierarchical model: a proposal for a model to be applied in the investigation of risk factors for severe diarrhea].

In epidemiological investigations of infant diseases, data are usually collected on a large set of variables. The associations between presumptive risk factors and the outcome is commonly evaluated through statistical modeling, but the model-building strategies are seldom described. In the project, data collected in a case-control study of risk factors for dehydrating diarrhea in infants have been used to present a hierarchized approach to the assessment of risk factors. The variables were grouped into a hierarchy of categories, ranging from distal determinants to proximate ones. These categories included, in this order, socioeconomic, environmental, reproductive maternal, nutritional and demographic sets. According to the univariate analyses all variables were associated with the outcome. As the purpose was to identify a parsimonious model to explain the data, in each set the confounders were selected through backward elimination, according to an alpha level of 0.10. The risk factors were evaluated through logistic regression after adjustment for confounders in the same set or in hierarchically superior sets. This approach allows researchers to quantify the contribution of each level of adjustment, to understand the model-building strategy as well as interpret the independent associations. The goodness-of-fit assessed at each set showed significant improvements in the model. The gamma coefficient of association was employed to quantify the proportion of cases and controls correctly identified by comparing the observed value with that predicted by the variables in the model. The final model resulted in a gamma of 0.74. The children's ages did not improve the prediction of cases and controls, but they have been kept in the model as they affect some exposures such as breastfeeding.

Case-Control Studies↗
PubMed1996

Risk factors for childhood pneumonia among the urban poor in Fortaleza, Brazil: a case--control study.

Reported are the results of a case-control study carried out between July 1989 and June 1990 in Fortaleza city, Ceará State, Brazil, to determine the factors that place young children living in urban slum conditions at increased risk of contracting pneumonia. Cases were 650 under-2-year-olds with a radiological diagnosis of pneumonia who were recruited at the main paediatric hospital in the city over a full calendar year. Age-matched controls were recruited from the neighbourhood where the cases lived. Cases and controls were compared with respect to a variety of sociodemographic, environmental, reproductive, nutritional, and morbidity factors, and a risk factor questionnaire was administered to the mother of each child or to the child's normal guardian. Cases and controls were also weighed and measured. Malnutrition was the most important risk factor for childhood pneumonia in the study population, with weight-for-age, height-for-age, and weight-for-height also being important risk factors. In view of the high prevalence of stunting in the study population, there is an urgent need to reduce the level of malnutrition as a priority. Attendance at a day care centre was also associated with a high odds ratio. In view of the growing numbers of children attending day care centres in both developing and developed countries, it is essential that ways be identified to improve the design and management of such centres in order to minimize the risk of pneumonia. Increased risks of childhood pneumonia were also associated with low birth weight, non-breast-feeding, crowding, high parity, and incomplete vaccination status, but not with socioeconomic status or environmental variables. Finally, children who had suffered from previous episodes of wheezing or been hospitalized for pneumonia had a greater than threefold increased risk of contracting the disease.

Adult↗