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Editorials |
1 From the Hematology Service, Texas Children's Cancer Center and Hematology Service, Houston, TX
See corresponding article on page 1611.
Recently, the World Health Organization estimated that anemia effects one-quarter of the world's population and is concentrated within preschool age children and women (1). Iron deficiency (ID) is estimated to be the most common cause of anemia worldwide and is particularly prevalent in developing nations in Africa and Asia (2). Other nutritional deficiencies certainly play a role in the occurrence of anemia, but the global prevalence data for these deficiencies are limited. Within the United States, beginning with reports from 1985, there has been a steady decline in the prevalence of anemia, particularly among infants and children. Previous explanations for the decline in anemia in children suggest that the implementation of iron fortification of select foods and infant formulas together with the establishment of the Special Supplement Nutrition Program for Women, Infants, and Children (WIC) in the 1970s have contributed to these effects. To date, for women of childbearing age (20–49 y), there has been no evidence of a similar decline.
In this issue of the Journal, Cusick et al (3) examined recent data on the burden of anemia in these 2 high-risk groups. Using data from the third and fourth National Health and Nutrition Examination Survey (NHANES), the authors investigated changes in the prevalence of several types of anemia, including anemia secondary to ID anemia (IDA), folate deficiency, vitamin B-12 deficiency, vitamin A deficiency, elevated lead, and inflammation. The good news, from this excellent review, is that there is a continued decline in the prevalence of anemia in children and women. The problem is that investigators are uncertain as to why.
Specifically, between the 2 study cohorts, there has been a continued decline in the prevalence of anemia among children, from 8.0% to 3.6%, but no significant change in the already low prevalence of IDA. For women, there has also been a similar significant decline in the overall prevalence of anemia, from 10.8% to 6.9%. There has also been a decline in the prevalence of folate deficiency and anemia from 4.1% to 0.5%. However, there remains a significant disparity in the prevalence of anemia by race-ethnicity, with the prevalence of whites (3.3%) compared with blacks (24.4%) and Mexican Americans (8.7%). In addition, there has not been a significant decline in the prevalence of IDA overall or when stratified by race-ethnicity. Logistic regression models that include patient demographics, laboratory testing methods, and known causes of anemia are unable to account for these findings. The introduction of folic acid fortification of all US enriched grain products in 1998 was thought to be a factor in the decline of folate deficiency, but statistical models did not demonstrate an effect on the decline in anemia prevalence in this data set. The authors are left with a challenge to point to public health strategies that have been successful in effecting a change and to new interventions to correct persistent problems. How might the practicing health care provider view these data?
Multiple factors may confound the analysis of the prevalence of anemia and include the presence or absence of recent infections, obesity, menstrual dysfunction, and dietary behaviors. Perhaps regular ongoing access to health care services rather than income criteria would be a more useful demographic variable for tracking outcomes. Anemia itself may not be the most important outcome measure when assessing for nutritional deficiencies. For example, in ID states, anemia is the last finding to appear and the first to clear with therapy. Early termination of iron replacement therapy is a common reason for persistent ID and recurrent IDA.
Regardless of the epidemiologic challenges, this study and other recent reports using the NHANES data set highlight important remaining problems and questions. The fact that about 25% of black women between 20 and 49 y of age are anemic should be considered a public health crises. According to reports by Brotanek et al (4), based on current NHANES data, the prevalence of ID in children 1–3 y of age (8%) has not significantly changed in 26 y. For certain groups—Hispanics (12.2%), younger children (11.5%), children who have been bottle-fed beyond 12 mo (12%), and the overweight (20.3%)—the prevalence remains high (4, 5). Although the prevalence of IDA remains low, the persistence of the iron-deficient state is probably more important. The potential for adverse effects associated with ID remain until the tissue stores are replenished. For women, the data for IDA and presumably ID are equally distressing, particularly among black and Mexican American groups. We are nowhere near the goals for Healthy People 2010, which target ID at <5% for 1–2-y-olds and <7% for women aged 12–49 y. Clearly, public health programs, such as WIC, have helped improve nutrition for women and children. However, continued access to health care, comprehensive follow-up, and compliance with care among high-risk populations may be as important for the improvement of these statistics (6). Cusick et al have set the stage for the need for further cohort studies to address additional variables affecting the prevalence of anemia, alternative measures for recognizing and managing ID, and new public health strategies to help manage those patient cohorts who are most vulnerable.
ACKNOWLEDGMENTS
The author had no personal or financial conflict of interest.
REFERENCES
Related articles in AJCN:
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