Philippe Bocquier

Overview of migration, poverty and health dynamics in Nairobi City's slum settlements

The Urbanization, Poverty, and Health Dynamics research program was designed to generate and provide the evidence base that would help governments, development partners, and other stakeholders understand how the urban slum context affects health outcomes in order to stimulate policy and action for uplifting the wellbeing of slum residents. The program was nested into the Nairobi Urban Health and Demographic Surveillance System, a uniquely rich longitudinal research platform, set up in Korogocho and Viwandani slum settlements in Nairobi city, Kenya. Findings provide rich insights on the context in which slum dwellers live and how poverty and migration status interacts with health issues over the life course. Contrary to popular opinions and beliefs that see slums as homogenous residential entities, the findings paint a picture of a highly dynamic and heterogeneous setting. While slum populations are highly mobile, about half of the population comprises relatively well doing long-term dwellers who have lived in slum settlements for over 10 years. The poor health outcomes that slum residents exhibit at all stages of the life course are rooted in three key characteristics of slum settlements: poor environmental conditions and infrastructure; limited access to services due to lack of income to pay for treatment and preventive services; and reliance on poor quality and mostly informal and unregulated health services that are not well suited to meeting the unique realities and health needs of slum dwellers. Consequently, policies and programs aimed at improving the wellbeing of slum dwellers should address comprehensively the underlying structural, economic, behavioral, and service-oriented barriers to good health and productive lives among slum residents.

Is There an Urban Advantage in Child Survival in Sub-Saharan Africa? Evidence From 18 Countries in the 1990s

Evidence of higher child mortality of rural-to-urban migrants compared with urban nonmigrants is growing. However, less attention has been paid to comparing the situation of the same families before and after they migrate with the situation of urban-to-rural migrants. We use DHS data from 18 African countries to compare child mortality rates of six groups based on their mothers’ migration status: rural nonmigrants; urban nonmigrants; rural-to-urban migrants before and after they migrate; and urban-to-rural migrants before and after they migrate. The results show that rural-to-urban migrants had, on average, lower child mortality before they migrated than rural nonmigrants, and that their mortality levels dropped further after they arrived in urban areas. We found no systematic evidence of higher child mortality for rural-to-urban migrants compared with urban nonmigrants. Urban-to-rural migrants had higher mortality in the urban areas, and their move to rural areas appeared advantageous because they experienced lower or similar child mortality after living in rural areas. After we control for known demographic and socioeconomic correlates of under-5 mortality, the urban advantage is greatly reduced and sometimes reversed. The results suggest that it may not be necessarily the place of residence that matters for child survival but, rather, access to services and economic opportunities.

Do migrant children face greater health hazards in slum settlements? Evidence from Nairobi, Kenya

Between 60% and 70% of Nairobi City’s population live in congested informal settlements, commonly referred to as slums, without proper access to sanitation, clean water, health care and other social services. Children in such areas are exposed to disproportionately high health hazards. This paper examines the impact of mother and child migration on the survival of more than 10,000 children in two of Nairobi’s informal settlements—Korogocho and Viwandani—between July 2003 and June 2007, using a two-stage semi-parametric proportional hazards (Cox) model that controls for attrition and various factors that affect child survival. Results show that the slum-born have higher mortality than non-slum-born, an indication that delivery in the slums has long-term health consequences for children. Children born in the slums to women who were pregnant at the time of migration have the highest risk of dying. Given the high degree of circular migration, factors predisposing children born in the slums to recent migrant mothers to higher mortality should be better understood and addressed.

Migration and the epidemiological transition: Insights from the Agincourt sub-district of northeast South Africa

Background Migration and urbanization are central to sustainable development and health, but data on temporal trends in defined populations are scarce. Healthy men and women migrate because opportunities for employment and betterment are not equally distributed geographically. The disruption can result in unhealthy exposures and environments and income returns for the origin household. Objectives The objectives of the paper are to describe the patterns, levels, and trends of temporary migration in rural northeast South Africa; the mortality trends by cause category over the period 2000-2011; and the associations between temporary migration and mortality by broad cause of death categories. Method Longitudinal, Agincourt Health and Demographic Surveillance System data are used in a continuous, survival time, competing-risk model. Findings In rural, northeast South Africa, temporary migration, which involves migrants relocating mainly for work purposes and remaining linked to the rural household, is more important than age and sex in explaining variations in mortality, whatever the cause. In this setting, the changing relationship between temporary migration and communicable disease mortality is primarily affected by reduced exposure of the migrant to unhealthy conditions. The study suggests that the changing relationship between temporary migration and non-communicable disease mortality is mainly affected by increased livelihood benefits of longer duration migration. Conclusion Since temporary migration is not associated with communicable diseases only, public health policies should account for population mobility whatever the targeted health risk. There is a need to strengthen the rural health care system, because migrants tend to return to the rural households when they need health care.Background Migration and urbanization are central to sustainable development and health, but data on temporal trends in defined populations are scarce. Healthy men and women migrate because opportunities for employment and betterment are not equally distributed geographically. The disruption can result in unhealthy exposures and environments and income returns for the origin household. Objectives The objectives of the paper are to describe the patterns, levels, and trends of temporary migration in rural northeast South Africa; the mortality trends by cause category over the period 2000–2011; and the associations between temporary migration and mortality by broad cause of death categories. Method Longitudinal, Agincourt Health and Demographic Surveillance System data are used in a continuous, survival time, competing-risk model. Findings In rural, northeast South Africa, temporary migration, which involves migrants relocating mainly for work purposes and remaining linked to the rural household, is more important than age and sex in explaining variations in mortality, whatever the cause. In this setting, the changing relationship between temporary migration and communicable disease mortality is primarily affected by reduced exposure of the migrant to unhealthy conditions. The study suggests that the changing relationship between temporary migration and non-communicable disease mortality is mainly affected by increased livelihood benefits of longer duration migration. Conclusion Since temporary migration is not associated with communicable diseases only, public health policies should account for population mobility whatever the targeted health risk. There is a need to strengthen the rural health care system, because migrants tend to return to the rural households when they need health care.

Health and demographic surveillance systems: contributing to an understanding of the dynamics in migration and health

Background Migration is difficult to measure because it is highly repeatable. Health and Demographic Surveillance Systems (HDSSs) provide a unique opportunity to study migration as multiple episodes of migration are captured over time. A conceptual framework is needed to show the public health implications of migration. Objective/design Research conducted in seven HDSS centres [International Network for the Demographic Evaluation of Populations and Their Health (INDEPTH) Network], published in a peer-reviewed volume in 2009, is summarised focussing on the age-sex profile of migrants, the relation between migration and livelihoods, and the impact of migration on health. This illustrates the conceptual structure of the implications of migration. The next phase is described, the Multi-centre Analysis of the Dynamics In Migration And Health (MADIMAH) project, consisting of workshops focussed on preparing data and conducting the analyses for comparative studies amongst HDSS centres in Africa and Asia. The focus here is on the (standardisation of) determinants of migration and the impact of migration on adult mortality. Results The findings in the volume showed a relatively regular age structure for migration among all HDSS centres. Furthermore, migration generally contributes to improved living conditions at the place of origin. However, there are potential negative consequences of migration on health. It was concluded that there is a need to compare results from multiple centres using uniform covariate definitions as well as longitudinal analysis techniques. This was the starting point for the on-going MADIMAH initiative, which has increased capacity at the participating HDSS centres to produce the required datasets and conduct the analyses. Conclusions HDSS centres brought together within INDEPTH Network have already provided strong evidence of the potential negative consequences of migration on health, which contrast with the beneficial impacts of migration on livelihoods. Future comparative evidence using standardised tools will help design policies for mitigating the negative effects, and enhancing the positive effects, of migration on health.Background Migration is difficult to measure because it is highly repeatable. Health and Demographic Surveillance Systems (HDSSs) provide a unique opportunity to study migration as multiple episodes of migration are captured over time. A conceptual framework is needed to show the public health implications of migration. Objective/design Research conducted in seven HDSS centres [International Network for the Demographic Evaluation of Populations and Their Health (INDEPTH) Network], published in a peer-reviewed volume in 2009, is summarised focussing on the age–sex profile of migrants, the relation between migration and livelihoods, and the impact of migration on health. This illustrates the conceptual structure of the implications of migration. The next phase is described, the Multi-centre Analysis of the Dynamics In Migration And Health (MADIMAH) project, consisting of workshops focussed on preparing data and conducting the analyses for comparative studies amongst HDSS centres in Africa and Asia. The focus here is on the (standardisation of) determinants of migration and the impact of migration on adult mortality. Results The findings in the volume showed a relatively regular age structure for migration among all HDSS centres. Furthermore, migration generally contributes to improved living conditions at the place of origin. However, there are potential negative consequences of migration on health. It was concluded that there is a need to compare results from multiple centres using uniform covariate definitions as well as longitudinal analysis techniques. This was the starting point for the on-going MADIMAH initiative, which has increased capacity at the participating HDSS centres to produce the required datasets and conduct the analyses. Conclusions HDSS centres brought together within INDEPTH Network have already provided strong evidence of the potential negative consequences of migration on health, which contrast with the beneficial impacts of migration on livelihoods. Future comparative evidence using standardised tools will help design policies for mitigating the negative effects, and enhancing the positive effects, of migration on health.

Healthy or unhealthy migrants? : Identifying internal migration effects on mortality in Africa using health and demographic surveillance systems of the INDEPTH network

Migration has been hypothesised to be selective on health but this healthy migrant hypothesis has generally been tested at destinations, and for only one type of flow, from deprived to better-off areas. The circulatory nature of migration is rarely accounted for. This study examines the relationship between different types of internal migration and adult mortality in Health and Demographic Surveillance System (HDSS) populations in West, East, and Southern Africa, and asks how the processes of selection, adaptation and propagation explain the migration-mortality relationship experienced in these contexts. The paper uses longitudinal data representing approximately 900 000 adults living in nine sub-Saharan African HDSS sites of the INDEPTH Network. Event History Analysis techniques are employed to examine the relationship between all-cause mortality and migration status, over periods ranging from 3 to 14 years for a total of nearly 4.5 million person-years. The study confirms the importance of migration in explaining variation in mortality, and the diversity of the migration-mortality relationship over a range of rural and urban local areas in the three African regions. The results confirm that the pattern of migration-mortality relationship is not exclusively explained by selection but also by propagation and adaptation. Consequences for public health policy are drawn.

Are health and demographic surveillance system estimates sufficiently generalisable

ABSTRACT Sampling rules do not apply in a Health and Demographic Surveillance System (HDSS) that covers exhaustively a district-level population and is not meant to be representative of a national population. We highlight the advantages of HDSS data for causal analysis and identify in the literature the principles of conditional generalisation that best apply to HDSS. A probabilistic view on HDSS data is still justified by the need to model complex causal inference. Accounting for contextual knowledge, reducing omitted-variable bias, detailing order of events, and high statistical power brings credence to HDSS data. Generalisation of causal mechanisms identified in HDSS data is consolidated through systematic comparison and triangulation with national or international data.

African urbanization trends and prospects

The paper aims at analysing and projecting urbanization trends using United Nations, World Urbanization Prospects data, 2007 Revision. A third order polynomial is used to model urban-rural growth difference from 1950 to 2005 country by country. The results of the model are compared to UN projection on urban growth for the period 2010-2050. Using the new model, the African urban population is projected to stagnate around its current level below 40%, with little variations by regions up to 2050, while the UN predicts 62%. The findings suggest that UN projections are excessively high and do not match the level of economic and social development in Africa.

Migration Analysis Using Demographic Surveys and Surveillance Systems

Although migration analysis is not a core objective of Demographic and Health Surveys (DHS) and Health and Demographic Surveillance Systems (HDSS), these demographic sources can be quite helpful for the study of migration, either as the event of interest or as a determinant. This chapter presents useful criteria on the basis of sampling and data collections procedures to evaluate such data sources as regard to migration analysis. This chapter justifies a number of advices illustrated with examples from DHS and HDSS data: Limiting the analysis to three years before the survey and to large geographical areas is important to analyze migration matrices without biases; Analyses of interactions between migration and another event should check for the order of these events; Migration as a determinant should be a time-varying covariate that includes information on origin and destination and reasons for migration; Migration is a major source of bias through informative censoring for the analysis of other events of interest; Information prior to migration and follow-up after migration are important improvements that should be encouraged in existing data collection programs.

A training manual for event history data management using Health and Demographic Surveillance System data

ObjectiveThe objective of this research note is to introduce a training manual for event history data management. The manual provides a first comprehensive guide to longitudinal Health and Demographic Surveillance System (HDSS) data management that allows for a step-by-step description of the process of structuring and preparing a dataset for the calculation of demographic rates and event history analysis. The research note provides some background information on the INDEPTH Network, and the iShare data repository and describes the need for a manual to guide users as to how to correctly handle HDSS datasets.ResultsThe approach outlined in the manual is flexible and can be applied to other longitudinal data sources. It facilitates the development of standardised longitudinal data management and harmonization of datasets to produce a comparative set of results.