Development of a research child growth reference and its comparison with the current international growth reference.

OBJECTIVE: To better characterize childhood growth and further assess potential limitations of the current National Center for Health Statistics and World Health Organization international growth reference. DESIGN: The LMS method was used for curve fitting to summarize the changes in height and weight distributions by 3 curves representing the skewness (L), median (M), and coefficient of variation (S). A series of polynomial regression procedures was applied to smooth the L, M, and S curves. SETTING: Subset data from 18 states contributing clinic data to the Centers for Disease Control and Prevention Pediatric Nutrition Surveillance System were used for this research reference. METHODS: We chose only those clinics in which the height and weight distributions of children closely matched with those of the first and second National Health and Nutrition Examination Surveys. RESULTS: Unlike the current international growth reference, the new reference has no disjunction at 24 months of age because it is based on a single data source for children aged 0 to 59 months. The reference also better characterizes the growth for infants than the current international reference, a fact we demonstrated with data from the National Health and Nutrition Examination Surveys, Pediatric Nutrition Surveillance System 1995, and the Davis Area Research on Lactation, Infant Nutrition, and Growth studies. CONCLUSIONS: The current National Center for Health Statistics and World Health Organization international growth reference needs to be updated. The methods used in this study will be useful to evaluate other data sets and to evaluate future modifications of growth references.

Increasing prevalence of overweight among US low-income preschool children: the Centers for Disease Control and Prevention pediatric nutrition surveillance, 1983 to 1995.

OBJECTIVE: To determine whether the prevalence of overweight in preschool children has increased among the US low-income population. DESIGN: Analysis using weight-for-height percentiles of surveillance data adjusted for age, sex, and race or ethnicity. SETTING: Data from 18 states and the District of Columbia were examined. SUBJECTS: Low-income children <5 years of age who were included in the Centers for Disease Control and Prevention Pediatric Nutrition Surveillance System. RESULTS: The prevalence of overweight increased from 18.6% in 1983 to 21.6% in 1995 based on the 85th percentile cutoff point for weight-for-height, and from 8.5% to 10.2% for the same period based on the 95th percentile cutoff point. Analyses by single age, sex, and race or ethnic group (non-Hispanic white, non-Hispanic black, and Hispanic) all showed increases in the prevalence of overweight, although changes are greatest for older preschool children. CONCLUSION: Overweight is an increasing public health problem among preschool children in the US low-income population. Additional research is needed to explore the cause of the trend observed and to find effective strategies for overweight prevention beginning in the preschool years.

Childhood obesity: future directions and research priorities.

The threat of obesity is greater than ever for US children and adolescents. All indications are that the current generation of children will grow into the most obese generation of adults in US history. Furthermore, there is every expectation that the next generation of children is likely to be fatter and less fit than the current generation. Despite the recognition of the severe health and psychosocial damage done by childhood obesity, it remains low on the public agenda of important issues facing policy makers. Perhaps this is because the most serious health effects of obesity in today's children will not be seen for several decades. Action must be taken now to stem the epidemic of childhood obesity. This action will require a prioritization of research into the etiology, treatment, and prevention of childhood obesity. It is unlikely that sufficient resources for such research will be available from public and private sources until the issue of childhood obesity is moved higher on the public agenda.

Coordinated strategies for controlling micronutrient malnutrition: a technical workshop.

Participants in a November 1991 workshop concluded that coordinated strategies for controlling malnutrition due to iodine, iron, vitamin A and other micronutrients deficiencies are technically feasible and should be given consideration in planning control efforts. Coordinated surveys involving clinical, biochemical and dietary assessment of multiple micronutrients are feasible. Multiple fortification is also possible using such vehicles as salt, processed rice or sugar. Supplementation efforts can be integrated with existing health care programs. Food-based strategies are also effective. The best examples have been community-based and have included a strong nutrition and health education component designed to change food consumption patterns, improve food preservation and preparation practices, and link income-generating activities with food production activities. Successful coordinated efforts will require a strong political commitment and a supportive infrastructure. Specific recommendations include the formation of national coordinating bodies for micronutrient deficiency control, establishment of a micronutrient information network and expansion of technical exchange and training.

Pregnancy nutrition surveillance system--United States, 1979-1990.

Since 1979, the CDC Pregnancy Nutrition Surveillance System (PNSS) has monitored behavior and nutritional risk factors among low-income pregnant women participating in public health programs. Although the states contributing to the system have varied over the period, the PNSS is able to characterize the behavior and health outcomes of pregnant women from diverse low-income populations. In 1990, 66.2% of the women in the system initiated prenatal care during the first trimester of pregnancy; 26.4% smoked during pregnancy. Since 1979, the prevalence of smoking remained relatively stable for white women, but declined for blacks and Hispanics. Prepregnancy body mass index (BMI, defined as kg/m2) showed marked changes from 1979 through 1990; the prevalence of underweight (BMI < 19.8) declined steadily and the prevalence of overweight (BMI > 26) increased steadily. In 1990, 39.3% of the women had gestational weight gains below levels recommended by the National Academy of Sciences. Both prepregnancy underweight and inadequate gestational weight gain were associated with greater risk for low birth weight in the PNSS. The prevalence of anemia at each trimester has remained stable since 1979. In 1990, 9.8%, 13.8%, and 33% of the women reported by the PNSS were anemic in the first, second, and third trimesters, respectively. Anemia in the first trimester appeared to be strongly associated with a high risk of low birth weight; this association was attenuated in later trimesters. These findings indicate the need to improve iron nutrition among low-income women.

Pediatric nutrition surveillance system--United States, 1980-1991.

The CDC Pediatric Nutrition Surveillance System (PedNSS) monitors the general health and nutritional characteristics of low-income U.S. children who participate in multiple public health programs. This system is intended to characterize trends and patterns in key indicators of nutritional status so that the information can be used for program planning and targeting. The indicators monitored by PedNSS are birth weight, childhood growth status, anemia, and breast-feeding patterns. From 1980 through 1991, the trends for low birth weight, low height-for-age (shortness), low weight-for-height (thinness), and high weight-for-height (overweight) were stable for all children monitored by the PedNSS, with the exception of Asian children, who were predominantly of Southeast Asian refugee background. In the early 1980s, the prevalence of low birth weight and shortness was higher among Asian children than among children of other racial or ethnic groups who were monitored by the PedNSS. However, these prevalences declined steadily from 1980 through 1991. By 1991, the prevalences of low birth weight and shortness for Asian children were similar to those observed for children of other races/ethnic groups. Overall, low-income U.S. children had a slightly lower height-for-age than expected, indicating that some of these children were at a health and nutritional disadvantage. The prevalence of overweight varied among different racial/ethnic groups; Hispanic and Native American children had the highest prevalences of overweight. The 20%-30% prevalence of anemia among low-income children monitored by the PedNSS was higher than among the general population, reflecting in part the preferential enrollment and retention of anemic children by public health nutrition programs and also indicating that many children had inadequate iron nutrition. From 1980 through 1991, the prevalence of anemia declined > 5% for most of the age- and race/ethnicity-specific groups monitored by PedNSS. That decline represents an improvement in iron nutritional status. PedNSS is a useful system for the monitoring and characterization of the nutrition status of low-income children at both state and national levels.

Using linked program and birth records to evaluate coverage and targeting in Tennessee's WIC program.

Public health nutrition programs are intended to serve low-income families who are at greater nutritional risk than the general population. Not all persons who are program-eligible are at equal risk, however. It would be desirable to evaluate a program's ability to enroll persons from higher risk backgrounds in the population (coverage) and, conversely, the extent to which those enrolled in this program are at higher risk (targeting). A method for the evaluation of coverage and targeting was developed using data from the Tennessee Women, Infants, and Children Special Supplemental Food Program (WIC) linked with birth certificates. The linked computer file was created by matching the name and date of birth in both record files. The birth records were the common source of information used to characterize the risk background for both the WIC and non-WIC participants. Maternal sociodemographic information on the birth records was used to define the health risk background of each child. The coverage and targeting of "at-risk" children were computed and compared for 50 counties or county-aggregates in Tennessee. Considerable variation in the coverage and targeting rates of at-risk children was observed among Tennessee counties, although the counties within each WIC administrative region tended to have similar coverage and targeting patterns. Using the existing data in linked program and vital records provides a direct evaluation of a program. Coverage and targeting evaluation can be used to detect underserved populations within small geographic areas.

Methodological issues in nutrition surveillance: the CDC experience.

Nutrition surveillance systems serve to provide state- and locality-specific data that are useful for the management of public health nutrition programs. Current systems, such as the Pediatric and Pregnancy Nutrition Surveillance Systems coordinated by the Centers for Disease Control (CDC), collect program-based data focused on nutrition problems in infants, children, and pregnant women. These systems provide highly useful information, but also present significant methodological challenges relating to representativeness, quality control, and indicator sensitivity/specificity. As the importance of nutritional risk factors for chronic disease is increasingly recognized, the concept of nutrition surveillance must be expanded beyond maternal and child nutrition to include nutrition-related behaviors and risk factors in adolescents and adults. The Behavioral Risk Factor Surveillance System (BRFSS), coordinated by CDC, collects telephone survey data that include information on nutrition-related issues such as overweight, weight-loss practices, and cholesterol screening. In addition, a school-based surveillance system is being established by CDC in coordination with state education agencies to assess adolescent health behaviors, including nutrition. The operation of these nutrition surveillance systems presents significant methodological issues that must be considered in interpreting and using the data for public health purposes.

Surveillance of severe pediatric undernutrition: conceptual and practical issues.

Despite a high level of concern among health professionals and the general public, data are inadequate to define and monitor the prevalence of severe pediatric undernutrition (SPUN). The Centers for Disease Control is supporting four state health departments to test the feasibility of surveillance mechanisms for SPUN. These efforts will seek to develop workable case definitions, define prevalence estimates, identify high-risk populations and describe specific demographic, social and medical risk factors. Initial experience with SPUN surveillance indicates that a variety of approaches may prove feasible but that these require attention to issues such as measurement error, data collection burden, confidentiality and data management. SPUN surveillance may prove too costly to be practical for general application, but it can serve as a means to identify needy children and estimate the prevalence of undernutrition in specific high-risk populations.

Racial/ethnic differences in smoking, other risk factors, and low birth weight among low-income pregnant women, 1978-1988.

Because of the adverse effects of low birth weight (LBW) on infant morbidity and mortality, one of the 1990 health objectives for the nation has been to reduce the incidence of LBW to 5% among all live births in the United States. Public health surveillance of cigarette smoking during pregnancy has demonstrated an association between smoking and an increased risk of LBW, defined as birth weight of less than 2,500 g. For the period 1978-1988, information on nearly 248,000 women from CDC's Pregnancy Nutrition Surveillance System showed an LBW rate of 6.9%, a high prevalence of smoking during pregnancy (29.7%); and a strong association between smoking during pregnancy and the likelihood of delivering an LBW infant in all age, racial/ethnic, and prepregnancy weight groups. The risk of LBW was greater for smokers than for nonsmokers (9.9% versus 5.7%), creating an excess LBW risk of 4.2% associated with smoking. Overall, the average birth-weight deficit related to smoking was 178 g. Among both smokers and nonsmokers, black women had a higher percentage of LBW infants than did white women, and the risk of LBW related to smoking was greater among black women. That risk tended to increase with age, especially among women with low pregravid weight. Major reductions in LBW might be achieved if smoking were eliminated among pregnant women.

Birth weight and childhood growth.

Most previous studies of the relationship between birth weight and childhood growth have concentrated on the growth of low birth weight infants. To examine this relationship throughout the full range of birth weights, growth data for children less than 5 years of age from the Tennessee Special Supplemental Food Program for Women, Infants, and Children linked to birth certificate records for 1975 to 1985 were used. Growth status was compared for 500-g birth weight categories from 1,000 g to 4,999 g using mean Z scores and the percentage of children more than 2 SD above or less than 2 SD below the median for height for age, weight for age, and weight for height. Infants with lower birth weights were likely to remain shorter and lighter throughout childhood, especially those who were intrauterine growth retarded rather than premature. Conversely, those infants with higher birth weights were likely to remain taller and heavier and to have a higher risk of obesity. Birth weight is a strong predictor of weight and height in early childhood, not only for low birth weight children but also for those of normal and high birth weight.

Altitude and childhood growth.

To assess the possible influence of altitude on childhood growth in the United States, we used data collected by the Centers for Disease Control Pediatric Nutrition. Surveillance System from eight mountain states to determine the height and weight status of children aged 5 years or younger enrolled in various public health programs between 1982 and 1984. The mean birth weight, height-for-age, weight-for-age, and weight-for-height indicators were found to decline significantly with increasing altitude, starting at an elevation greater than 1500 m (p less than 0.001, ANOVA). The reduction in growth was observed for all age groups and all birth weight groups studied. Part of the observed reduction in growth could be attributed to the lower birth weight of children born at higher altitude. However, the reduced growth status persisted after controlling for birth weight, suggesting the presence of an extrauterine growth retardation effect related to altitude.

A method for evaluating systems of epidemiological surveillance.

Epidemiological surveillance is the systematic collection, analysis and dissemination of health data for the planning, implementation and evaluation of public health programmes. Established surveillance systems should be regularly reviewed on the basis of explicit criteria of usefulness, cost and quality; systems should be modified as a result of such review. Attributes of quality include: (i) sensitivity, (ii) specificity, (iii) representativeness, (iv) timeliness, (v) simplicity, (vi) flexibility and (vii) acceptability. To date, evaluation of surveillance systems has been limited in scope and content. The evaluation method proposed in this article offers an organized approach to the evaluation of epidemiological surveillance systems. The usefulness of a surveillance system is measured by whether it leads to prevention or control or a better understanding of adverse health events. The measure can be qualitative, in terms of the subjective views of those using the system, or quantitative in terms of the impact of surveillance data on policies, interventions or the occurrence of a health event. The cost of a system includes indirect as well as direct costs, and should be measured in relation to the benefits obtained, such as reduction of medical-care expenses and of time lost from work. All elements of the system should be included in the cost: data collection, analysis and dissemination. The sensitivity of a surveillance system is its ability to detect health events (completeness of reporting). Its specificity is inversely proportional to the number of false positives it reports. Reports of a disease that do not meet the case definition are false positives, and may result in resources being wasted in investigating them.(ABSTRACT TRUNCATED AT 250 WORDS)

PIP: Epidemiological surveillance is the systematic collection, analysis, and dissemination of health data for the planning, implementation, and evaluation of public health programs. Established surveillance systems should be regularly reviewed on the basis of explicit criteria of usefulness, cost, and quality; systems should be modified as a result of such a review. Attributes of quality include: 1) sensitivity; 2) specificity; 3) representativeness; 4) timeliness; 5) simplicity; 6) flexibility; and 7) acceptability. The usefulness of a surveillance system is measured by whether it leads to prevention or control or a better understanding of adverse health events. The measure can be qualitative or quantitative. The cost of a system includes indirect as well as direct costs, and should be measured in relation to the benefit obtained. The sensitivity of a surveillance system is its ability to detect health events (completeness of reporting). Its specificity is inversely proportional to the number of false positive reports. Representativeness can be measured by comparing surveillance data covering part of the population to either nationwide data, where available, or to random sample-survey data. Simplicity in a system means it is easy to understand and implement, and is therefore usually relatively cheap and flexible. A flexible system is easily adapted by adding new notifiable diseases or conditions or extending it to additional population groups. Acceptability depends on perceived public health importance of the event under surveillance, recognition of individual contributions and time required for reports.

Alcohol use and health behavior lifestyles among U.S. women: the behavioral risk factor surveys.

Alcohol use is a complex behavior, occurring in the context of an overall health lifestyle. We used data from a nationally representative telephone survey (N = 12,467 women) to examine associations between binge drinking, chronic drinking, and other health behaviors. Certain health-risk behaviors (e.g., smoking, drunk driving, and seatbelt nonuse) tend to cluster with alcohol misuse. These may act synergistically, thus augmenting the negative health effects of alcohol misuse. Conversely, some health behaviors (e.g., eating or exercising, particularly in response to stress) are negatively associated with alcohol misuse and may serve similar functions for some women. Finally, binge drinking occurs more frequently among women who may have relatively restrictive eating behaviors and higher levels of interpersonal stress. Our findings suggest that alcohol prevention and treatment programs should address sociodemographic and health lifestyle factors that initially predispose an individual to engage in health-risk behaviors and should recognize the interdependent patterns of behaviors associated with alcohol misuse. This approach will help prevent substitutions, recurrence, or induction of detrimental behaviors and will identify potentially negative interactions between existing concurrent health-risk behaviors.