Wealth, wealth indices and HIV risk in East Africa.

83 Volume 33, Number 2, June 2007 For nearly two decades, the conviction that poverty fuels the spread of HIV in Sub-Saharan Africa has been ubiquitous among epidemiologists and development workers.1–3 In 2005, however, a team of epidemiologists4 published a comment in The Lancet drawing attention to some surprising findings: Demographic and Health Survey (DHS) data from Kenya and Tanzania appear to demonstrate that HIV prevalence is highest among the wealthiest segments of those populations, and lowest among the poor.5,6 In light of these findings, the authors suggested that wealth, rather than poverty, may be the root cause of behavioral risk for HIV in Sub-Saharan Africa. This interpretation of DHS findings depends on the validity of the measurement of wealth. I argue here that the DHS approach to measuring wealth is inconsistent with the complexities of contemporary African livelihoods. As a result, the conclusion that wealth fuels the spread of HIV in East Africa may be misleading. Neither the Kenyan nor the Tanzanian survey collected direct measurements of individual or household wealth. Rather, both used a recently developed measure called the DHS Wealth Index, which was created by investigators working at ORC Macro, the U.S. firm that collaborates with governments of developing countries to monitor trends in socioeconomic conditions, demographic behavior and health via periodic surveys.7 The purpose of the index is to quantify the economic resources of households without directly asking household members about their incomes and expenditures or the total value of their assets. This is a laudable goal. Even in developed countries, where most households have bank accounts and checkbooks and compute their incomes annually for tax purposes, measures of income and wealth based on self-reported data are notoriously unreliable.8 The DHS Wealth Index circumvents this problem by using a simple inventory of selected assets for each household; principal components analysis is then applied to summarize this inventory in a single dimension. Other investigators, working independently, have developed similar approaches to quantifying variations in household wealth in developing countries.9 Clearly, the index measures something of social significance, as shown by its strong correlation with diverse social and health outcomes. The association with HIV prevalence is but one example. Yet the significance of these DHS findings to an understanding of the socioeconomic forces underlying the HIV epidemics of Sub-Saharan Africa depends on how we interpret the index. If we interpret it as presented—that is, as a measure of wealth—then our discussion may reasonably be limited to how HIV prevalence varies along a unidimensional continuum from extreme poverty to extreme wealth, and how either poverty or wealth, or both, may be implicated in the creation of behavioral risk for HIV. However, when one considers the profound transformations of Sub-Saharan African economies and ways of life that have occurred over the past two centuries, another interpretation of the DHS Wealth Index and its association with HIV prevalence becomes apparent. Historically, wealth in these social systems has taken a limited number of forms, which varied according to the local ecology and culture.10,11 In many places, ownership of cattle was the most important form of wealth. In other areas, the primary form of wealth was the control of human labor through kinship systems. More recently, sustained population growth and increased opportunities for trade led to a shortage of arable land, and thus land itself became an important form of wealth.12 As a result of these and other changes, the people of SubSaharan Africa today base their livelihoods on two separate but interdependent sectors of the economy—traditional forms of subsistence production and the growing cash economy.10,13 Like the former, the latter takes diverse forms, from cash cropping of coffee and other goods for the global market, to wage labor in the mining and tourism industries or on plantations, to employment in government agencies. Some people rely mainly on traditional forms of subsistenceoriented agricultural production, while others rely more on the cash economy. Most people are members of families that have some stake in both sectors, though the balance varies from family to family, from ethnic group to ethnic group and from place to place. With these economic and cultural transformations in mind, the DHS Wealth Index takes on an additional interpretation as a measure not only of wealth, but also of involvement in the modern cash economy as opposed to the traditional sector. Most of the assets that are counted in the index are commodities purchased with cash in modern markets—radios, bicycles, telephones and so forth.7 Traditional forms of wealth, including cattle, land and the control of human labor through kinship systems, are either not included in the index at all (as in the 1998 Kenya DHS) or constitute a small minority of the indicator variables used to form the index (as in the 1995 Egypt DHS). Moreover, when traditional forms of wealth are included, it appears that they actually contribute negatively to the index. This is apparent when one considers the proportion Wealth, Wealth Indices and HIV Risk in East Africa