Elsevier

Social Science & Medicine

Volume 68, Issue 4, February 2009, Pages 699-707
Social Science & Medicine

Early origins of health disparities: Burden of infection, health, and socioeconomic status in U.S. children

https://doi.org/10.1016/j.socscimed.2008.12.010Get rights and content

Abstract

Recent work in biodemography has suggested that lifetime exposure to infection and inflammation may be an important determinant of later-life morbidity and mortality. Early exposure to infections during critical periods can predispose individuals to chronic disease, in part through the reallocation of energy away from development needed for immune and inflammatory responses. Furthermore, markers of inflammation are known to vary by socioeconomic status in adults and may contribute to overall socioeconomic health inequalities, but little is known about how the sources of this inflammation differ over the life course. This paper uses novel biomarker data from the Third National Health and Nutrition Examination Survey (NHANES III) to test the association of the burden of common chronic infections (Helicobacter pylori (H. pylori), cytomegalovirus (CMV), herpes simplex virus-1 (HSV-1), hepatitis A and hepatitis B) with height-for-age and asthma/chronic respiratory conditions in U.S. children ages 6 and older, and the association of these chronic infections to children's socioeconomic status. A higher burden of infection is found to be associated with lower height-for-age as well as an increased likelihood of asthma net of race/ethnicity, family income, and parental education. Children with lower family income, lower parental education, and non-white race/ethnicity have a higher likelihood of infection with several individual pathogens as well as the overall burden of infection. Differential exposure and/or susceptibility to infections may be one mechanism through which early social factors get embodied and shape later-life health outcomes.

Section snippets

Background

Recent work in biodemography has suggested that reductions in lifetime exposure to infection and inflammation may have been an important determinant of cohort declines in later-life morbidity and mortality. Crimmins and Finch argue that cohorts with lower infectious disease mortality in childhood can be characterized by a “cohort morbidity phenotype” that links their early-life experience to later-life cohort mortality patterns (Crimmins and Finch, 2006, Finch and Crimmins, 2004). More broadly,

Data

The analyses are based on data from the National Health and Nutrition Examination Survey (NHANES III), collected between 1988 and 1994. NHANES III contains a cross-sectional representative sample of the U.S. civilian non-institutionalized population, with an oversample of Mexican-Americans and non-Hispanic blacks. Data were collected in household face-to-face interviews and medical examinations, which included the collection of blood and urine for laboratory tests. Data were collected in two

Sociodemographics

Childhood socioeconomic status was measured using the years of education of the household reference person and annual family income. Family income was coded as the midpoint of each of the 26 reported categories (using $65,000 for the incomes above $50,000) and adjusted for inflation between the two NHANES III phases using the Consumer Price Index. Income was log-transformed due to the skewness of the distribution. Education was measured as the highest completed year of schooling and was used in

Methods

First, we calculated means (s.e.) and proportions for key analysis variables. Next we estimated tetrachoric (polychoric) correlations among the five infection seropositivity status indicators and used a likelihood ratio test to determine whether the correlations were statistically significant. Logit models were then used to estimate the association of race/ethnicity, education, and income with seropositivity to individual infections, as well as the association between the infections and the

Associations among individual infections

Table 2a shows tetrachoric correlations among the five individual infections. The correlations show a moderate positive association between most infection pairs. Correlations among H. pylori, CMV, and HSV-1 are generally stronger (0.25–0.37) than those with hepatitis A and B (ranging from 0.04 to 0.29). Overall, these results suggest some degree of clustering of individual infections that might indicate a shared environment of pathogen exposure or susceptibility.

Table 2b shows results from the

Discussion

To our knowledge, this is the first study to examine the relationship between the burden of chronic infections and socioeconomic status in U.S. children. The results show that family income, parental education, and race/ethnicity are significantly associated with the likelihood of infection with several persistent infections in U.S. children aged 6–16, as well as the overall burden of multiple infections. These differences in the burden of infection at early ages might have important

Acknowledgements

Jennifer Dowd acknowledges funding from the Robert Wood Johnson Health and Society Scholars Program, the University of Michigan during the writing of the paper. Anna Zajacova acknowledges funding from the National Institute of Aging and Population Studies Center, University of Michigan. Revision of this paper was also supported by NIH grant R21 NR011181-01.

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