Background: Iron deficiency (ID) and anemia are priority public health challenges for young children, especially in low-income countries. Better design and evaluation of child health programs require the quantitative identification of these health concerns and their risk factors.
Objectives: A primary goal of this research is to examine potential methods for adjusting biomarker data to account for the relationships between both inflammation and malaria and certain biomarkers for iron and vitamin A. The ultimate aim is to identify the direct and indirect risk factors for ID, severe anemia, and anemia.
Methods: Three cross-sectional surveys of young children in Africa provide the data for this dissertation, two in Western Kenyan and one national survey in Malawi. Correction factors adjusting for C-reactive protein (CRP), alpha-1-acid glycoprotein (AGP), and malaria were applied to ferritin, soluble transferrin receptor (sTfR), body iron stores, retinol-binding protein (RBP); differences in prevalence of ID, iron-deficiency anemia (IDA), and vitamin A deficiency (VAD) were compared across adjustments. Linear and logistic regression analyses were used to examine the association of ID and anemia with unadjusted and adjusted iron and vitamin A status, sociodemographic factors, morbidity, growth, and genetic polymorphisms. Candidate nutrient-nutrient, infection-nutrient, genetic-nutrient and malaria-nutrient mediators for anemia were further examined in a path analysis.
Results: Adjustments to ferritin resulted in substantially higher reported ID while adjustments to sTfR and RBP reduced ID and VAD, respectively. Adjustments using AGP resulted in a greater prevalence difference than using CRP or malaria. Factors consistently associated with hemoglobin and anemia in Kenya were: CRP, AGP, sTfR, ferritin, RBP, malaria, age, sex, breastfeeding, alpha-thalassemia, and stunting. Fewer associations were found in the Malawi survey. Inflammation-adjustments to ferritin, sTfR, and RBP values altered their association to anemia in the majority of models. Path analysis did not support the role of vitamin A status as a mediator between the iron biomarkers and anemia. There was a trend for malaria mediating the relationship between G6PD and anemia (P-value<0.10) and malaria resulted in higher iron stores and erytheriopetic drive. While there was no mediation effect between malaria and sickle cell or alpha-thalassemia on anemia, these genetic disorders altered iron biomarker values.
Conclusion: The present study findings highlight the importance of accounting for CRP or AGP, and to a lesser extent malaria, in the selection, use and interpretation of iron and vitamin A biomarkers. These findings will be of particular use in settings where there is a high prevalence of inflammation and malaria. Several major contributors to anemia were identified in this study and emphasize the need for an integrated approach to ameliorate anemia in low-income countries. Potentially important interventions include improved infant feeding practices, reducing stunting, and the control and prevention of ID, vitamin A deficiency, and malaria.
|Commitee:||Cleary, Sean, Flores-Ayala, Rafael, Jefferds, Maria Elena, Raiten, Daniel|
|School:||The George Washington University|
|School Location:||United States -- District of Columbia|
|Source:||DAI-B 75/07(E), Dissertation Abstracts International|
|Subjects:||African Studies, Nutrition, Public health, Developmental biology, Epidemiology|
|Keywords:||Alpha-1-acid glycoprotein, Anemia, C-reactive protein, Iron deficiency, Kenya, Malaria, Malawi, Vitamin a deficiency|
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