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.

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.

Declining prevalence of anemia among low-income children in the United States.

To determine the anemia trends among low-income US children, hematologic measurements obtained from children aged 6 to 60 months who were enrolled in public health programs in six states that were consistently monitored by the Centers for Disease Control Pediatric Nutrition Surveillance System were studied. Overall, the prevalence of anemia has declined steadily from 7.8% in 1975 to 2.9% in 1985. The prevalence of anemia declined significantly among children seen at preenrollment screening visits, as well as those seen at follow-up visits, suggesting a generalized improvement in childhood iron nutritional status in the United States, as well as a positive impact of public health programs. To ensure that the declining trend of anemia was not a function of a change in the population of children enrolled in the surveillance system, Tennessee nutrition surveillance records were further analyzed; these records were linked with birth records to obtain detailed socioeconomic status (SES) information. Even though the SES composition remained stable from 1975 to 1984, the prevalence of anemia has declined significantly within each SES group. These findings indicate a true decline in the prevalence of anemia among low-income children that is likely the result of improvements in childhood iron nutrition.