[Data on birthweight in developing countries: are surveys useful?]. / Datos sobre el peso al nacer en países en desarrollo: son útiles las encuestas?

The main source of data on birth weight in developing countries is statistics from health facilities, although most developing countries do not produce annual estimates of the incidence of low birth weight from these data. Such estimates would be subject to selection bias as the data are usually limited to babies born within health facilities, and therefore are representative of a subgroup that is markedly different from the overall population of neonates. Since 1990 the Demographic and Health Surveys programme has included questions on recalled birth weight and relative size at birth in 15 national surveys. In this article, we show that these cross-sectional surveys can provide a useful data source for making national estimates of mean birth weight and the incidence of low birth weight. The extent of misclassification of birth weight is, however, too large to use the data on relative size as birth as an indicator of low birth weight at the individual level.

Datos sobre el peso al nacer en países en desarrollo: son útiles las encuestas? / Data on birth weight in developing countries: can surveys help?

Las estadísticas de centros de atención de salud son la fuente principal de datos sobre el peso al nacer en los países en desarrollo, si bien en la mayor parte de esos países no se producen estimaciones anuales de la incidencia de bajo peso al nacer a partir de esos datos. Si se produjeran, las estimaciones serían propensas al sesgo de selección ya que los datos están limitados en general a los niños nacidos en centros de salud y, por lo tanto, representan un subgrupo decididamente diferente de la población general de neonatos. Desde 1990, el programa de Encuestas Demográficas y de Salud ha realizado 15 encuestas nacionales en las que se incluyeron preguntas sobre el peso y el tamaño relativo al nacer tal como los recordaban las madres. Este artículo muestra que las encuestas transversales pueden constituir una fuente útil de datos para estimar la media nacional de peso al nacer y la incidencia de bajo peso. Sin embargo, la clasificación errónea del peso al nacer es demasiado extensa para emplear los datos de tamaño relativo al nacer como indicador de bajo peso a escala individual

The professionals and patients involved in dental examinations are at risk for infection by various disease-causing bacteria, viruses, and fungi, such as those responsible for hepatitis, tuberculosis, herpes, and AIDS. It is known that aerosols and spatter containing pathogenic microorganisms can spread during an examination. Nevertheless, some dental clinics are designed to have multiple examination areas in the same room, with no physical barriers between them. The objective of this study was to verify the reach of spatter resulting from the use of a triple syringe and high-rotation turbine during five simulated exams in a collective clinic, bearing in mind that spattercan contain the patient's saliva and blood. To facilitate tracking of the spatter, aniline dye (pink, blue, yellow, green, and brown) was added to the water in the appropriate receptacle in each of the five units. The room, the equipment, and the patient's and operator's clothing were covered with white paper. A high concentration of spatter was observed on the chair, the operator, and the floor of each unit, and it also appeared on the chairs and trays of the surrounding units. The maximum distance reached by spatter was 1.82 m from a point on the chair corresponding to the position of the patient's mouth. During real simultaneous examinations, the surrounding chairs and their patients and operators, as well as the trays containing sterilized instruments, are within spatter range. Therefore, there is a real possibility of crossinfection, and physical barriers should be placed between the units. This study also confirmed the need for protection of the operator's face, body, hair, and arms, since these regions were heavily affected by spatter.

Household structure and childhood immunization in Niger and Nigeria.

In this study, we use data from the Demographic and Health Surveys to examine the relationship between household structure and childhood immunization in Niger and Nigeria. We show that household structure is an important determinant of childhood immunization in Nigeria: Children from nuclear, elementary polygynous, and three-generational households are worse-off than those from laterally extended households. However, the lower odds of full immunization among children from three-generational and elementary polygynous households are attributable to low economic status and low maternal education levels, respectively. In Niger, household structure does not have a significant effect on children's likelihood of being fully immunized.

Data on birth weight in developing countries: can surveys help?

The main source of data on birth weight in developing countries is statistics from health facilities, although most developing countries do not produce annual estimates of the incidence of low birth weight from these data. Such estimates would be subject to selection bias as the data are usually limited to babies born within health facilities, and therefore are representative of a subgroup that is markedly different from the overall population of neonates. Since 1990 the Demographic and Health Surveys programme has included questions on recalled birth weight and relative size at birth in 15 national surveys. In this article, we show that these cross-sectional surveys can provide a useful data source for making national estimates of mean birth weight and the incidence of low birth weight. The extent of misclassification of birth weight is, however, too large to use the data on relative size at birth as an indicator of low birth weight at the individual level.

PIP: Data from 15 surveys conducted in developing countries that included questions on birth weight were analyzed to determine whether birth weight data from cross-sectional surveys can be used to improve national estimates of mean birth weight and the incidence of low birth weight (LBW). The proportion of children weighed at birth ranged from 9% in Pakistan and Yemen to 91% in the Dominican Republic. Most women could recall the birth weight. Units of measurement to record birth weight included grams in seven surveys, kilograms carried to one decimal place in five surveys, kilograms carried to two decimal places in one survey, pounds and ounces in one survey, and pounds or kilograms in one survey. Among all surveys reporting in kilograms or grams, 33-50% of birth weights were recorded in multiples of 500 g. The sensitivity of the relative-size-at-birth indicator to identify LBW babies was very low in all surveys (mean, 29%), even though the positive predictive value (PPV) was at least 70% in most surveys. Thus, most infants reported as very small were indeed LBW, but only 29% of all LBW infants were identified. When one used both very small and small as indicators of LBW, sensitivity improved greatly (mean, 66%). Yet 45% (mean PPV) of the very small and small infants were of LBW. The incidence of LBW, when considering both numerical weight and size, ranged from 8.7% (Colombia) to 18.8% (Tanzania). Poor data quality probably accounted for the fact that data from Yemen were very different than those from the other surveys. These findings suggest that these surveys can be a useful data source for estimating mean birth weight nationwide and the incidence of LBW. Misclassification of birth weight is too common to use the data on relative size at birth as an indicator of LBW at the individual level.

Demographic and health surveys (DHS): contributions and limitations.

Surveys conducted in the context of the Demographic and Health Surveys (DHS) programme are an important source of data on health of families in developing countries. Both at the national and international level, DHS surveys provide much-needed data on fertility and family planning, on mortality and nutrition, and on health services utilization. The use of uniform survey instruments allows detailed international and subnational comparisons of health status and health care. Limitations of the DHS surveys are also discussed.

PIP: Demographic and Health Surveys (DHS), funded by the USAID, were first initiated in 1984 as an expansion of World Fertility Survey (WFS) type data. DHS collected qualitative information on health and nutrition, as well as WFS data on fertility, child mortality, and family planning. DHS surveys used nationally representative samples of women of childbearing age and, most recently, samples of males. National government organizations usually administered the survey and analyzed results. A core questionnaire was adapted to each country's special needs. A list of the 44 countries conducting a DHS was provided with additional information on the most recent year/s of the survey and number of respondents. The core questionnaire included questions on fertility and mortality, anthropometry, family planning, maternity care, child feeding, vaccination, child morbidity, and AIDS. The surveys were useful in providing a wide variety of health indicators and health services indicators. Data quality checks were conducted continuously in order to improve instruments, to assure trained field personnel, to use concurrent data entry and editing, and to provide feedback to interviewers during field administration of the instrument. Results were published very quickly, and tabulations were available within 2-3 months after field work is completed. The limitations included reporting and recall bias, particularly for age or other retrospective data relying on memory of a past event. Omissions were not considered a serious problem. Individual level data required more careful interpretation. District level analysis was preferred because it corresponded with major health program levels. Samples of 1000-1500 women were required for valid estimation of fertility and child mortality. Expansion was considered unlikely because of the current length of the questionnaire. Consideration was given to supplementary modules or to inclusion of saliva or blood testing for AIDS. Countries adopting the health goals of the World Summit for Children could use DHS for base line information.

Child anthropometry in cross-sectional surveys in developing countries: an assessment of the survivor bias.

In cross-sectional surveys, the sample of children with anthropometric measurements is not representative of all children in a birth cohort, since only children surviving to the survey date are measured. This survivor bias may have implications for studies of trends and differentials in anthropometric indicators. In this paper, the effects of the survivor bias on the estimates of child anthropometric indicators are assessed by 1) reviewing evidence from longitudinal studies on the prevalence of malnutrition among deceased children and among surviving children and by 2) analyzing retrospective data on child mortality and cross-sectional data on child anthropometry in 17 national surveys that are part of the Demographic and Health Surveys Program. It is concluded that comparisons of anthropometric data across geographic units, population subgroups, and calendar time are marginally affected by the survivor bias, unless mortality differences between the birth cohorts are very large (e.g., well over 50 per 1,000 births).

PIP: The effects of survivor bias in cross-sectional surveys of anthropometric measurements of children, that is overestimates due to omission of children that died before the survey date, were estimated by reviewing longitudinal studies for prevalence of malnutrition in deceased and surviving children, and analyzing retrospective data on child mortality and cross-sectional data on child anthropometry. Data were taken from 17 Demographic and Health Surveys, collected from 1986-1989. The odds ratio of the prevalence of malnutrition in deceased to that of living children was computed to assess how much worse the nutritional status of deceased children is to surviving children. In most countries 50% of the dead children were malnourished. The ratios were higher if malnutrition was more severe, specifically if the differences were pronounced for weight for age, and weight for height, or for severe stunting, below -3 SD from the median height for age. The proportion dead among children 3-36 months ranged from 2.5% in Sri Lanka to 15% in Mali, and was higher in older children. The largest bias was seen in weight for age: e.g., in Mali, where mortality is highest, the proportion of underweight increased by 4.6%, and of severely underweight by 2.7%. There was a relationship between level of malnutrition and child mortality at the country level, with considerable variation between countries, and a few outstanding outliers, countries whose malnutrition was much higher than expected from mortality rates. The effects of mother's education and of length of preceding birth interval were computed, and the odds ratio rose only from 1.8 to 2.2. It was concluded that comparisons of anthropometric data across countries and time are only marginally affected by survivor bias, unless the mortality differences between birth cohorts are very large, over 50/1000 births.

Accuracy and completeness of mothers' recall of diarrhoea occurrence in pre-school children in demographic and health surveys.

In the context of the Demographic and Health Surveys program (DHS), data were collected on diarrhoeal diseases in childhood and related treatment patterns. In this paper we assess the accuracy and completeness of mothers' recall of diarrhoea in 19 national DHS surveys and discuss the implications for health interview surveys in developing countries. It is concluded that there is under-reporting of diarrhoea if the recall period is longer than 2-3 days, whereas there may be over-reporting of very recent or current diarrhoea in most DHS surveys. Reporting errors appear to vary considerably between countries, which affects the comparability of survey results. A second and related issue, that is addressed in this paper, is the reporting of treatment practices by duration of diarrhoeal episode. There were no major differences in reported treatment patterns between children with diarrhoea that terminated in the last two weeks and children with current diarrhoea of at least two days' duration. The implications of the findings for retrospective surveys on childhood morbidity and treatment patterns are discussed.

Bottle use for infant feeding in developing countries: data from the demographic and health surveys. Has the bottle battle been lost?

This paper uses data from 22 national surveys in developing countries to estimate the use of bottles for feeding of infants under 6 months of age. These data were collected in the context of the Demographic and Health Surveys programme (DHS) between 1986 and 1989. Bottle use appears to be very common in most countries. Only six of the 22 countries had levels of bottle use of less than 20 per cent, and all these countries are in sub-Saharan Africa. The policy implications are discussed briefly.

Breast milk antibody to the capsular polysaccharide of Haemophilus influenzae type b.

Breast milk has a high concentration of secretory immunoglobulin and potentially could serve as a source of passive antibody protection of infants against systemic invasion by Haemophilus influenzae type b. Specific antibody to the capsular polysaccharide of this organism was detected in the colostrum and all subsequent milk samples in 11 of 12 women with a radioactive antigen binding assay. The geometric mean concentrations of antibody were 1.99 microgram/ml in colostrum and 0.18 microgram/ml in breast milk at six weeks and after four and one-half to six months of lactation. Antibody levels in colostrum correlated positively with those in subsequent milk samples; levels after six weeks of lactation correlated highly with those present after four and one-half to six months of lactation. IgA was the predominant immunoglobulin class of anticapsular antibody in the colostrum and milk samples as detected by an enzyme-linked immunosorbent assay.