«Title of Dissertation: DETERMINANTS OF CHILDHOOD MORBIDITY AND THE ROLE OF MALNUTRITION: EVIDENCE FROM INDONESIA Shannon Leigh Wilson, Doctor of ...»
Title of Dissertation: DETERMINANTS OF CHILDHOOD MORBIDITY AND
THE ROLE OF MALNUTRITION:
EVIDENCE FROM INDONESIA
Shannon Leigh Wilson, Doctor of Philosophy, 2009
Dissertation directed by: Professor Maureen Cropper
Department of Economics
Professor Anna Alberini
Department of Agricultural and Resource Economics
Studies that have attempted to examine the impact of early childhood malnutrition on acute illness have failed to adequately establish the causal link from malnutrition to acute illness. The empirical challenge arises because household behavioral decisions that influence investment in a child's nutrition and growth are very likely correlated with other household decisions that affect a child's incidence of illness. These include decisions to invest in hygiene and sanitation or a mother’s knowledge and use of appropriate feeding practices. There may also be unobserved risk factors, such as genetic endowments, which introduce correlation between one of the regressors – nutritional status – and the error term in a disease production equation.
In this dissertation, I test two basic hypotheses: (1) chronic undernutrition in early childhood, as measured by stunting in children under five, increases the probability of contemporaneous acute illness; and (2) there is a significant effect of early childhood malnutrition on the probability of developing acute illness later in childhood. I estimate a model that predicts the incidence of febrile, diarrheal and respiratory disease, diseases which combined account for the greatest total burden of morbidity and mortality in children in developing countries.
I focus my research on contemporaneous and longer-term acute illness outcomes in children under five for three reasons. First, substantial research has shown that children are at greatest risk of malnutrition in the early years of life, particularly before age two (Victora et al. 2008; Ruel et al 2008). In this period, children are no longer exclusively breastfeed and they have high nutritional requirements because they are growing quickly. Second, the burden of infectious disease is disproportionately borne by children under five due to their relatively immature immune systems and their dependence on caregivers to use appropriate feeding and hygiene practices to avoid infection (Martorell 1999; Martorell and Habicht 1986). Third, since most of the literature on the long-term consequences for human capital formation focuses on conditions in early childhood, by placing this research question in the same context, it can be more clearly seen as contributing to the broader literature on human capital formation.
I employ instrumental variables to allow identification of the impact of early childhood malnutrition on acute illness. I use a panel dataset from three waves of the Indonesian Family Life Survey (IFLS) to address the measurement challenges that arise due to the unobservable household factors that influence both the likelihood of early childhood malnutrition and acute illness, and the synergistic nature of malnutrition and infection.
My results show a strong and statistically significant contemporaneous effect of malnutrition on the likelihood of acute illness. I find that children under five who are stunted are 16 percent more likely than children who are not stunted to report symptoms of acute illness. I find that the impact of malnutrition on the likelihood of acute illness remains positive and significant four years into the future. Children who were stunted in 1993 are still 5 percent more likely than non-stunted children to experience acute illness in 1997. While I find this impact of early childhood stunting on future illness outcomes dissipates seven years later, I present suggestive evidence that this may reflect the fact that many of the children in my sample who were stunted in 1993 are in fact no longer stunted by 2000. Overall, these results suggest that efforts at reducing early childhood malnutrition can lead not only to immediate health benefits in terms of lower rates of infectious disease, but also lead to better health outcomes in the future.
Many international organizations and bilateral donors are prioritizing improvements in early childhood nutrition with the goal of improving long-term human capital outcomes (World Bank 2002; USAID 2008). The most important implication of my results is that improvements in early childhood nutrition and reducing the burden of disease are complementary objectives; improved early childhood nutrition will facilitate meeting the Millennium Development Goal of reducing the burden of disease. Further, to the extent improvements in pre-school nutritional status reduce either the incidence of acute illness, the severity of acute illness episodes, or both, such improvements may have indirect benefits. These include reducing school absenteeism which likely will enhance the acquisition of knowledge at school and lead to higher school completion rates
Professor Maureen L. Cropper, Co-chair Professor Anna Alberini, Co-chair Professor Peter Coughlin Professor Vivian Hoffman Professor Kenneth L. Leonard © Copyright by Shannon Leigh Wilson Dedication For my girls, who gave me reason to persevere.
I owe an enormous debt of gratitude to my advisors, Professor Maureen Cropper and Professor Anna Alberini, for their tireless efforts and tremendous patience while I juggled a variety of duties (parenting and full-time work among them) while completing this dissertation.
Professor Ken Leonard and Professor Vivian Hoffman provided great insights, and offered a number of suggestions which enriched the dissertation.
Early in my academic career, Professor Nancy Bockstael took me under her wing and provided amazing guidance. She encouraged me to choose a subject matter about which I am passionate. During an especially challenging time, she offered empathy I never expected to need but appreciated more than she will ever know.
My family (Mom especially!) provided words of encouragement along the way, even as they wondered if it would ever really happen.
My sweetheart, Bilal, endured countless hours of discussions, debates and diatribes (mostly mine). He stayed up into the wee hours on more occasions than I can count and helped me push through the last mile. I look forward to life post-dissertation…
Table of Contents
Chapter 1 Introduction and Statement of the Problem
Chapter 2 Malnutrition and Illness: Physiological Foundations and Literature Review
2.1 The Definition of Malnutrition and Common Indicators
2.2 Physiological Process of Growth and the Impact of Acute Illness on Nutritional Status
2.3 Review of the Medical Literature on Malnutrition, Morbidity and Mortality 19
2.5 Review of the Literature on Socio-Economic Determinants of Morbidity and Mortality
2.6 Contribution to the Literature
Chapter 3 Empirical Model
3.1 The Empirical Challenge
3.1 Analytical Framework
3.2 Estimation Strategy
Chapter 4 The Setting
4.1 Indonesia: Overview
4.2 Burden of Malnutrition in Indonesia
4.3 Burden of Infectious Disease in Indonesia
Chapter 5 The Indonesian Family Life Survey
5.1 Indonesian Family Life Survey
5.2 Sampling Frame
5.3 Tracking of Panel Respondents and Response Rates
5.6 Potential Selectivity Biases
6.1 Summary of Data Requirements
6.2 Description of the Sample
6.4 Description of Main Covariates
Chapter 7 Results
7.1 Summary Statistics
7.2 Does Early Childhood Stunting Explain Likelihood of Acute Illness?...... 100
7.3 Does Early Childhood Stunting Influence Future Illness Outcomes?...... 106
7.4 Robustness Checks
Tables and Figures
Chapter 8: Conclusion and Policy Implications
The goal of this dissertation is to test two hypotheses: chronic malnutrition in early childhood, as measured by stunting in children 0-5 years old, increases the probability of contemporaneous acute illness; and (2) early childhood malnutrition increases the probability of developing acute illness later in childhood. The hypotheses are tested using data from the 1993, 1997 and 2000 waves of the Indonesia Family Life Survey. Specifically, I examine the impact of malnutrition, measured by low height-for-age (stunting) on the probability that a child experiences febrile, diarrheal or respiratory disease. The remainder of this chapter motivates the importance of the topic and discusses the failure of the literature to adequately address it. This is followed by a description of my research strategy and a preview of key results.
Motivation and Limitations of the Existing Literature Infectious diseases kill between 14 and 17 million people each year and debilitate another 50 million. They cause 63 percent of all childhood deaths and 48 percent of premature deaths1 worldwide (WHO 2008a). Children under five years of age are particularly vulnerable to infectious diseases. More than 70 percent of all deaths from infectious disease occur in children under five, most due to largely preventable diarrheal, respiratory and febrile illnesses (WHO 2008;
Layne 2004). The overwhelming majority of new cases of infectious disease Defined as death before attaining average life expectancy, which varies by country, year and gender.
occur in developing countries where poor infrastructure, poor education, poor hygiene practices, crowding in urban areas and lack of universal access to high quality healthcare combine to create a disease-rich environment.
The global burden of malnutrition follows a similar socio-economic, demographic and geographic distribution. One in six people worldwide are malnourished, most in developing countries (Spielman and Pandya-Lorch 2009). Childhood undernutrition, in particular, is highly prevalent in developing countries. One-third of children under five years old in developing countries are stunted in growth (de Onis et al.2000), meaning that their height-for-age is significantly lower than would be expected in a well-nourished population.
Studies in the medical and the epidemiological literature have established a correlation between infectious disease and secondary malnutrition (malnutrition arising as a result of infection) (Scrimshaw, Taylor and Gordon 1968; Mosley and Chen 1984; Duggan et al.1986.). The same literature suggests that malnutrition may negatively impact the immune system and make one more susceptible to infection and/or more severe disease once infected (Scrimshaw, Taylor and Gordon 1968; Moore et al. 1997; Moore et al. 1999). Experts recently estimated that more than one-third of child deaths and 11 percent of the total disease burden worldwide are attributable to early childhood malnutrition (Bhutta et al.
2008). However, these estimates are based on an observed correlation between malnutrition and morbidity and mortality, not an established causation.
This literature suffers from econometric limitations because it fails to adequately account for the potential endogeneity of the health outcomes (Behrman 1996;
Glewwe and King 2001; Alderman, Hoddinott and Kinsey 2006). Studies that have attempted to examine the impact of early childhood malnutrition on acute illness have failed to adequately establish the causal link from malnutrition to acute illness. This is primarily because the household behavioral decisions that influence investment in a child's nutrition and growth are very likely correlated with other household decisions that would affect a child's probability of illness, such as decisions to invest in hygiene and sanitation or a mother’s knowledge and use of appropriate feeding practices. There may also be hidden risk factors, such as genetic endowment, which introduce correlation between one of the regressors – nutritional status – and the error term in a disease production equation. The complex synergism between malnutrition and infectious disease also creates a measurement challenge which makes it difficult to determine whether the relationship between malnutrition and infectious disease is causal and, if so, the direction of causality as well as the magnitude of the effect. The direction of causality is an empirical question which rests on the nature of the illness and whether malnutrition is measured by a short-term indicator such as wasting or a longer-term indicator such as stunting (Scrimshaw, Taylor and Gordon 1968).
Within the economics and medical literature, the effects of malnutrition have been shown to cause improvements in cognitive outcomes (Maluccio et al. 2006;
Case and Paxson 2008; Glewwe and King 2001), educational attainment (Behrman 1996; Brown and Pollitt 1996), chronic morbidity (Barker 1997; Barker 2002; Lucas 2006; Fisher et al. 2006) and premature adult mortality (Fisher et al.
2006; Choi et al. 2000). However, little is known about the impact of malnutrition on the incidence and severity of acute illness. Recent medical literature cites the lack of rigor applied to studies of the relationship between nutritional status and infectious disease and calls for the urgent need to incorporate techniques used in other disciplines to improve our understanding of the relationship between nutrition and immune function (Prentice et al. 2008; Victora et al. 2008; Black et al. 2008).