Ian M. Timæus

The socioeconomic determinants of HIV incidence: evidence from a longitudinal, population-based study in rural South Africa

Background:Knowledge of the effect of socioeconomic status on HIV infection in Africa stems largely from cross-sectional studies. Cross-sectional studies suffer from two important limitations: two-way causality between socioeconomic status and HIV serostatus and simultaneous effects of socioeconomic status on HIV incidence and HIV-positive survival time. Both problems are avoided in longitudinal cohort studies. Methods:We used data from a longitudinal HIV surveillance and a linked demographic surveillance in a poor rural community in KwaZulu-Natal, South Africa, to investigate the effect of three measures of socioeconomic status on HIV incidence: educational attainment, household wealth categories (based on a ranking of households on an assets index scale) and per capita household expenditure. Our sample comprised of 3325 individuals who tested HIV-negative at baseline and either HIV-negative or -positive on a second test (on average 1.3 years later). Results:In multivariable survival analysis, one additional year of education reduced the hazard of acquiring HIV by 7% (P = 0.017) net of sex, age, wealth, household expenditure, rural vs. urban/periurban residence, migration status and partnership status. Holding other factors equal, members of households that fell into the middle 40% of relative wealth had a 72% higher hazard of HIV acquisition than members of the 40% poorest households (P = 0.012). Per capita household expenditure did not significantly affect HIV incidence (P = 0.669). Conclusion:Although poverty reduction is important for obvious reasons, it may not be as effective as anticipated in reducing the spread of HIV in rural South Africa. In contrast, our results suggest that increasing educational attainment in the general population may lower HIV incidence.

Levels and Causes of Adult Mortality in Rural South Africa: The Impact of AIDS

Objective: To quantify the contribution that AIDS makes to adult mortality in rural South Africa. Design: Demographic surveillance of the population in a rural area of northern KwaZulu Natal province. Methods: The population and all adult deaths (n = 1021) in 2000 were enumerated. We conducted verbal autopsy interviews with the caregivers of those who died to identify the causes of adult deaths. A validation study of the verbal autopsy diagnoses was conducted on 109 individuals with hospital notes that could be located. Death rates and other mortality indices are both calculated directly and estimated indirectly by the orphanhood method. Results: Mortality in the study area rose sharply in the late-1990s. By 2000 the probability of dying between ages 15 and 60 was 58% for women and 75% for men. AIDS, with or without tuberculosis, is the leading cause of death in adulthood (48%). Injuries, mostly resulting from road traffic accidents or violence, cause 20% of deaths of men aged 15–44 years. In the age group 60 years or more, non-communicable diseases account for 76 and 71% of deaths of women and men respectively. Conclusions: This population has experienced a sudden and massive rise in adult mortality. This can be accounted for by AIDS deaths. Mortality from non-communicable disease and (among men) injuries is also high. Antenatal HIV seroprevalence continued to rise in rural KwaZulu Natal in the late 1990s, reaching 40% in some clinics in this area. Adult mortality will continue to rise unless effective treatment interventions are introduced.

Improved methods and assumptions for estimation of the HIV/AIDS epidemic and its impact: Recommendations of the UNAIDS Reference Group on estimates, modelling and projections

UNAIDS and WHO produce biannual country-specific estimates of HIV/AIDS and its impact. These estimates are based on methods and assumptions that reflect the best understanding of HIV epidemiology and demography at the time. Where significant advances are made in epidemiological and demographic research, the methods and assumptions must evolve to match these advances. UNAIDS established an Epidemiology Reference Group in 1999 to advise them and other organisations on HIV epidemiology and methods for making estimates and projections of HIV/AIDS. During the meeting of the reference group in 2001, four priority areas were identified where methods and assumptions should be reviewed and perhaps modified: a) models of the HIV epidemic, b) survival of adults with HIV-1 in low and middle income countries, c) survival of children with HIV-1 in low and middle income countries, and d) methods to estimate numbers of AIDS orphans. Research and literature reviews were carried out by Reference Group members and invited specialists, prior to meetings held during 2001-2. Recommendations reflecting the consensus of the meeting participants on the four priority areas were determined at each meeting. These recommendations were followed in UNAIDS and WHO development of country-specific estimates of HIV/AIDS and its impact for end of 2001.UNAIDS and WHO produce biannual country-specific estimates of HIV/AIDS and its impact. These estimates are based on methods and assumptions that reflect the best understanding of HIV epidemiology and demography at the time. Where significant advances are made in epidemiological and demographic research, the methods and assumptions must evolve to match these advances. UNAIDS established an Epidemiology Reference Group in 1999 to advise them and other organisations on HIV epidemiology and methods for making estimates and projections of HIV/AIDS. During the meeting of the reference group in 2001, four priority areas were identified where methods and assumptions should be reviewed and perhaps modified: a) models of the HIV epidemic, b) survival of adults with HIV-1 in low and middle income countries, c) survival of children with HIV-1 in low and middle income countries, and d) methods to estimate numbers of AIDS orphans. Research and literature reviews were carried out by Reference Group members and invited specialists, prior to meetings held during 2001-2. Recommendations reflecting the consensus of the meeting participants on the four priority areas were determined at each meeting. These recommendations were followed in UNAIDS and WHO development of country-specific estimates of HIV/AIDS and its impact for end of 2001.

Adult Mortality in Sub-Saharan Africa: Evidence From Demographic and Health Surveys

This article reports levels, trends, and age patterns of adult mortality in 23 sub-Saharan Africa countries, based on the sibling histories and orphanhood data collected by the countries’ Demographic and Health Surveys. Adult mortality has risen sharply since HIV became prevalent, but the size and speed of the mortality increase varies greatly among countries. Excess mortality is concentrated among women aged 25–39 and among men aged 30–44. These data suggest that the increase in the number of men who die each year has exceeded somewhat the increase for women. It is time for a systematic attempt to reconcile the demographic and epidemiological evidence concerning AIDS in Africa.

The South African fertility decline: Evidence from two censuses and a Demographic and Health Survey

Inadequate data and apartheid policies have meant that, until recently, most demographers have not had the opportunity to investigate the level of, and trend in, the fertility of South African women. The 1996 South Africa Census and the 1998 Demographic and Health Survey provide the first widely available and nationally representative demographic data on South Africa since 1970. Using these data, this paper describes the South African fertility decline from 1955 to 1996. Having identified and adjusted for several errors in the 1996 Census data, the paper argues that total fertility at that time was 3.2 children per woman nationally, and 3.5 children per woman for African South Africans. These levels are lower than in any other sub‐Saharan African country. We show also that fertility in South Africa has been falling since the 1960s. Thus, fertility transition predates the establishment of a family planning programme in the country in 1974.

The Spectrum projection package: improvements in estimating incidence by age and sex, mother-to-child transmission, HIV progression in children and double orphans.

Background The Spectrum program is used to estimate key HIV indicators from the trends in incidence and prevalence estimated by the Estimation and Projection Package or the Workbook. These indicators include the number of people living with HIV, new infections, AIDS deaths, AIDS orphans, the number of adults and children needing treatment, the need for prevention of mother-to-child transmission and the impact of antiretroviral treatment on survival. The UNAIDS Reference Group on Estimates, Models and Projections regularly reviews new data and information needs, and recommends updates to the methodology and assumptions used in Spectrum. Methods The latest update to Spectrum was used in the 2009 round of global estimates. This update contains new procedures for estimating: the age and sex distribution of adult incidence, new child infections occurring around delivery or through breastfeeding, the survival of children by timing of infection and the number of double orphans.

The impact of HIV-1 infection on mortality in children under 5 years of age in Sub-Saharan Africa: a demographic and epidemiologic analysis.

Objective:To estimate the effects of the HIV-1 epidemic on mortality in children under 5 years of age in urban and rural populations in eastern and central, and southern Africa.Method:A lifetable method that allows for the effects of competing causes (i.e., mortality due to HIV and other causes) was used to estimate mortality. Our calculations used published and unpublished data on HIV-1 infection in African adults and children (incidence and prevalence, vertical transmissions, transmission by blood transfusion and natural history), and typical baseline fertility and child mortality data. The results were applied to model rural and urban populations to explore the effects of parameters such as mortality in HIV-1-infected children, fertility in infected mothers and overall population growth.Results:We estimate that child mortality will rise substantially because of the prevalence of HIV-1 in urban areas. There will be little difference in the absolute levels of increase in mortality between areas in eastern and central, and southern Africa with similar levels of HIV infection; however, in relative terms the effect will be more noticeable in southern Africa because of the lower baseline mortality. Towns with severe epidemics (30% adult seroprevalence) might experience a rise in child mortality of one-third in eastern and central Africa and three-quarters in southern Africa. This will cancel or reverse existing advantages in urban over rural levels of child mortality and this effect will be more pronounced in southern Africa. The exact impact of HIV-1 will vary according to mortality among HIV-1-infected children and to fertility among infected women. However, changes in age structure and population growth have relatively little impact on mortality.Conclusions:There are likely to be substantial increases in child mortality in sub-Saharan Africa as a result of HIV-1 infection. The main determinant of childhood infection is the scale of the epidemic among adults. Increases in mortality will depend on local adult seroprevalence but are hard to predict precisely because of possible variation in death rates among HIV-1-infected children. In rural areas with low seroprevalence other diseases will remain the main cause of mortality. However, in urban areas families and health services will have to face considerably increased demands from ill and dying children.

Father figures : the progress at school of orphans in South Africa

Objective:To examine the progress in their schooling of maternal and paternal orphans in a province of South Africa with high AIDS mortality and contrast it with that of both children who lived in different households from their parents and children who resided with their parents. Methods:The KwaZulu-Natal Income Dynamics Study is a panel of households first interviewed in 1993. The 1998 and 2004 waves of fieldwork collected 5477 reports on children aged 8–20 years. We studied the determinants of the proportion of these children who had completed 2+ grades fewer than expected for their year of birth using both household fixed-effects models and difference-in-difference models fitted to children reported on twice. Results:Co-residence with a well-educated mother benefited childrens schooling, but the fixed-effects models provide no evidence that maternal orphanhood or living apart from their mother adversely affected childrens schooling. In contrast, both paternal orphanhood and belonging to a different household from ones father resulted in slower progress at school. Although absence of the father was associated with household poverty, this was not why it was associated with falling behind at school. Discussion:Both the substantial benefits of living with their fathers for childrens schooling and the limited importance of maternal orphanhood conflict with the results of most studies in this issue, including those of other research in the same part of South Africa. These findings caution against drawing general conclusions about the impact of the AIDS epidemic from a few studies of geographically localized populations.

Measurement of adult mortality in less developed countries: a comparative review.

This paper compares the direct and indirect methods used to measure adult mortality in the developing world. No other approach can substitute fully for accurate and complete vital registration but in many countries it is unrealistic to expect the registration system to cover the majority of the population in the foreseeable future....The difficulties involved in measuring adult mortality using surveys and other ad hoc inquiries are discussed....While the choice of methods must depend on each countrys situation direct questions require very large samples and are unreliable in single-round inquiries. On the other hand although indirect methods provide less detailed and up-to-date information than is ideal they are adequate for many practical purposes. In particular the experience of the 1980s suggests that questions about orphanhood perform better than earlier assessments indicated and recent methodological developments have circumvented some of the limitations of the indirect approach. (EXCERPT)

Birth intervals, postponement, and fertility decline in Africa: A new type of transition?

We investigated birth-interval dynamics in 24 African countries using data from 76 Demographic and Health Surveys conducted since 1986. Controlling for selection bias in the birth-history data using the Brass–Juárez method and regression models produced almost identical results. Birth intervals have lengthened in every country examined. This analysis uncovered a distinctive and previously undocumented pattern of childbearing that is prevalent across sub-Saharan Africa. After allowing for time trends in birth-interval length, the lengthening of birth intervals in almost every country varies little by womens age or parity. Moreover, in several countries, birth intervals are now too long to be explicable by birth spacing contingent on the age of womens youngest child. Rather, women are postponing births for other reasons. These findings offer empirical support for the idea that the fertility transition in sub-Saharan Africa is following a different pattern from that observed elsewhere.