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.

Mortality transition in the Ovamboland region of Namibia, 1930-1990

Few long-term statistical series exist that can document the mortality transition in Africa. This paper uses data from the parish registers of the Evangelical Lutheran Church in Namibia to study morality in Ovamboland between 1930 and 1990. The paper identifies significant discontinuities and reversals in the trend in mortality. Much of the mortality transition occurred in a rapid breakthrough concentrated between the early 1950s and early 1960s. Adult mortality fell more than existing model life tables would predict and the pattern of relatively high early-age mortality typical of modern Africa emerged only at this time. While a range of developments in Ovamboland contributed to the overall decline in mortality, the most important factor was the establishment, by the Finnish Mission, of a Western system of health care. In Ovamboland, the drive to 'good health at low cost' was articulated not through political institutions but through the church.

Impact of the HIV epidemic on mortality in sub-Saharan Africa: evidence from national surveys and censuses

OBJECTIVE

To measure recent trends in all-cause child and adult mortality in national populations in sub-Saharan Africa.

DESIGN

Secondary analysis of data collected in national household surveys and censuses.

METHODS

The index of infant and child mortality is the probability of dying before age 5 years (under-five mortality). For adult mortality, it is the probability of dying between ages 15 and 60 years. Mortality trends are assessed in three ways: (i) by comparison of data collected in the 1990s with those from the 1980s; (ii) using the retrospective reports of the survival of women's children and siblings collected by Demographic and Health Survey inquiries; and (iii) by comparing the latter estimates with estimates from data on orphanhood.

RESULTS

Under-five mortality is stagnant or rising in several African countries. In some countries, however, adverse trends developed too early in the 1980s to be attributable to HIV. In most countries, the three approaches to monitoring adult mortality yield consistent results. Adult death rates doubled or tripled between the 1980s and mid-1990s in Uganda, Zambia, and Zimbabwe. Mortality also rose substantially elsewhere in East and Central Africa but not in West Africa. Increases in mortality are concentrated among young adults. In general, men are worst affected, but in Uganda the rise in women's mortality is greater.

CONCLUSIONS

Data can be collected in national household surveys and censuses to monitor the mortality impact of HIV in Africa. Such data have begun to document the differential impact of the epidemic. In those countries with data in which HIV became prevalent by the late 1980s, massive rises in adult mortality occurred by the mid-1990s.

Estimation of adult mortality from paternal orphanhood: a reassessment and a new approach

"This article proposes a new procedure for estimating men's mortality from paternal orphanhood which generally yields more accurate results than the existing approach. A procedure for estimating mortality from maternal orphanhood data based on consistent assumptions is also presented. The theory underlying these methods is outlined.... The article also points out an error made in the tabulation of the weighting factors used until now to estimate mortality from paternal orphanhood. Investigations using simulated data are presented which support the theoretical arguments that suggest that the paternal orphanhood method is more robust than has often been assumed and which confirm that the new approach usually produces more accurate estimates than the weighting factors."

Estimation of mortality from orphanhood in adulthood

This paper extends earlier research into methods for estimating adult mortality from information on the recent incidence of orphanhood. It presents a series of regression coefficients for estimating female and male mortality from synthetic cohort data on the subsequent orphanhood of those who had a living mother or father at exact age 20. Such information can be obtained either where questions about parental survival have been asked in two inquiries or by asking retrospectively about dates of orphanhood in a single survey. Although the method is somewhat sensitive to errors in the reporting of ages and dates, it is a promising source of up-to-date estimates of adult mortality that are free from bias due to the underreporting of the orphanhood of young children ("the adoption effect").

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 country's 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."

Identifying health problems and health research priorities in developing countries

When we were invited to prepare this background paper on the health problems of the developing countries for the Commission on Health Research for Development, our first thought was to compile and organize available data on the causes of morbidity and mortality affecting different age groups in various populations. It soon became clear that this would not be especially useful. There are major gaps in the available data, particularly from the poorer countries and for people above 5 years of age. The data that are available are often of poor or uncertain quality, collected from unrepresentative or undefined subpopulations, and not strictly comparable due to different definitions and data-collection methods. Additionally, in the absence of agreed definitions and analytical frameworks, it is not clear what could or should be done with the data on health problems so amassed. More fundamentally, we have come to doubt whether the current array of epidemiological concepts and tools is sufficient for the task. We therefore decided that, while giving an overview of current knowledge on levels and trends of morbidity and mortality, the emphasis of this paper should be more towards concepts, methods, and data deficiencies. In Section 1, we set out definitions and frameworks for considering health problems and health research; we review recent conceptual models for the analysis of the determinants of child survival; and we outline a framework, focusing on modifiable determinants of health and life-cycle health effects, which is used in subsequent sections. In Section 2, relationships between national and societal level determinants and health are reviewed and then set aside. In Section 3, we review available data on world patterns and trends of morbidity and mortality, highlighting the data deficiencies and lacunae. In Section 4, we follow the life of a woman in a developing country and examine the health problems, and their determinants, which she and her children face. In Section 5, we draw these strands together and, having reviewed current approaches to prioritizing health problems and suggested some ways in which they could be improved, in Section 6 identify several research priorities, emphasizing the need for methodological research. This paper was commissioned in March 1987; prepared in draft and presented to a meeting at Chateau de Bossey, Geneva, Switzerland during 15-17 July; and revised and completed in September 1987. It is in no sense definitive or final.(ABSTRACT TRUNCATED AT 400 WORDS)