The empirical evidence for the impact of HIV on adult mortality in the developing world: data from serological studies

Factors influencing self-concept among adolescents infected with HIV: a cross-sectional survey in China

OVERVIEW

The mental health problems of adolescents with human immunodeficiency virus (HIV) are important. It is of great significance to explore which factors can affect the self-evaluation and understanding of adolescents with HIV.

OBJECTIVE

We found that adolescents with HIV have a lower level of self-concept than healthy adolescents. This study aimed to determine the factors influencing self-concept among adolescents with HIV in China.

SETTING

A questionnaire was distributed among a total of 290 adolescents in Henan Province, China. One hundred and forty questionnaires were distributed in the case group (adolescents with HIV) and the control group (healthy adolescents) was issued 150 questionnaires.The Piers-Harris Children's Self-concept Scale, the Perceived Stress Scale, the Perceived Social Support Scale and the Simplified Coping Style Questionnaire were adapted for a Chinese population. Differences between the groups were tested for significance using Student's t-test, and analysis of variance was used to test continuous variables. The relationship between environmental personality factors and adolescent self-concept was examined by Pearson correlation analysis. Hierarchical linear regression analysis was used to model the effects of environmental personality factors on self-concept.

RESULTS

The self-concept total score among adolescents with HIV was significantly lower than healthy adolescents (p<0.05). Hierarchical regression analysis indicated that age (β=-0.19, t=-2.16, p=0.03), perceived stress (β=-0.19, t=-2.22, p=0.03), perceived social support (β=0.26, t=3.25, p=0.00), positive coping style (β=0.50, t=5.75, p=0.00) and negative coping style (β=-0.45, t=-5.33, p=0.00) were significantly associated with self-concept total scores.

CONCLUSIONS

The self-concept of adolescents with HIV is related to perceived stress, perceived social support and coping style. These findings underline the significance of self-concept among adolescents infected with HIV.

Impact of Population Recruitment on the HIV Epidemics and the Effectiveness of HIV Prevention Interventions

Mechanistic mathematical models are increasingly used to evaluate the effectiveness of different interventions for HIV prevention and to inform public health decisions. By focusing exclusively on the impact of the interventions, the importance of the demographic processes in these studies is often underestimated. In this paper, we use simple deterministic models to assess the effectiveness of pre-exposure prophylaxis in reducing the HIV transmission and to explore the influence of the recruitment mechanisms on the epidemic and effectiveness projections. We employ three commonly used formulas that correspond to constant, proportional and logistic recruitment and compare the dynamical properties of the resulting models. Our analysis exposes substantial differences in the transient and asymptotic behavior of the models which result in 47 % variation in population size and more than 6 percentage points variation in HIV prevalence over 40 years between models using different recruitment mechanisms. We outline the strong influence of recruitment assumptions on the impact of HIV prevention interventions and conclude that detailed demographic data should be used to inform the integration of recruitment processes in the models before HIV prevention is considered.

Are Clade Specific HIV Vaccines a Necessity? An Analysis Based on Mathematical Models

As HIV-1 envelope immune responses are critical to vaccine related protection, most candidate HIV vaccines entering efficacy trials are based upon a clade specific design. This need for clade specific vaccine prototypes markedly reduces the implementation of potentially effective HIV vaccines. We utilized a mathematical model to determine the effectiveness of immediate roll-out of a non-clade matched vaccine with reduced efficacy compared to constructing clade specific vaccines, which would take considerable time to manufacture and test in safety and efficacy trials. We simulated the HIV epidemic in San Francisco (SF) and South Africa (SA) and projected effectiveness of three vaccination strategies: i) immediate intervention with a 20–40% vaccine efficacy (VE) non-matched vaccine, ii) delayed intervention by developing a 50% VE clade-specific vaccine, and iii) immediate intervention with a non-matched vaccine replaced by a clade-specific vaccine when developed. Immediate vaccination with a non-clade matched vaccine, even with reduced efficacy, would prevent thousands of new infections in SF and millions in SA over 30 years. Vaccination with 50% VE delayed for five years needs six and 12 years in SA to break-even with immediate 20 and 30% VE vaccination, respectively, while not able to surpass the impact of immediate 40% VE vaccination over 30 years. Replacing a 30% VE with a 50% VE vaccine after 5 years reduces the HIV acquisition by 5% compared to delayed vaccination. The immediate use of an HIV vaccine with reduced VE in high risk communities appears desirable over a short time line but higher VE should be the pursued to achieve strong long-term impact. Our analysis illustrates the importance of developing surrogate markers (correlates of protection) to allow bridging types of immunogenicity studies to support more rapid assessment of clade specific vaccines.

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Rapid deployment of non-clade matched HIV vaccines would be an effective public-health strategy in high risk populations.

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Pursuit of further incremental increase in vaccine efficacy is justified and will result in better long term effectiveness.

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Reduced condom use by vaccinated individuals may diminish the advantage of the replacement vaccination strategy.

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Reliable surrogate markers of vaccine efficacy are needed to speed up the development of effective HIV vaccines.

The HIV vaccine field has followed the concept of clade specific (clade matched) vaccines for over 30 years. We investigate the implementation of non-clade matched and clade specific vaccines by simulating the HIV epidemics in San Francisco and South Africa: two regions of the world where the epidemics are well characterized. Our analysis suggests that rapid deployment of a non-clade matched vaccine would be an effective public health strategy. The most effective 10-year vaccination strategy is to employ non-clade matched vaccines in highest risk populations followed by the rapid development of a more effective clade matched prototype.

Modeling age-specific mortality for countries with generalized HIV epidemics

BACKGROUND

In a given population the age pattern of mortality is an important determinant of total number of deaths, age structure, and through effects on age structure, the number of births and thereby growth. Good mortality models exist for most populations except those experiencing generalized HIV epidemics and some developing country populations. The large number of deaths concentrated at very young and adult ages in HIV-affected populations produce a unique 'humped' age pattern of mortality that is not reproduced by any existing mortality models. Both burden of disease reporting and population projection methods require age-specific mortality rates to estimate numbers of deaths and produce plausible age structures. For countries with generalized HIV epidemics these estimates should take into account the future trajectory of HIV prevalence and its effects on age-specific mortality. In this paper we present a parsimonious model of age-specific mortality for countries with generalized HIV/AIDS epidemics.

METHODS AND FINDINGS

The model represents a vector of age-specific mortality rates as the weighted sum of three independent age-varying components. We derive the age-varying components from a Singular Value Decomposition of the matrix of age-specific mortality rate schedules. The weights are modeled as a function of HIV prevalence and one of three possible sets of inputs: life expectancy at birth, a measure of child mortality, or child mortality with a measure of adult mortality. We calibrate the model with 320 five-year life tables for each sex from the World Population Prospects 2010 revision that come from the 40 countries of the world that have and are experiencing a generalized HIV epidemic. Cross validation shows that the model is able to outperform several existing model life table systems.

CONCLUSIONS

We present a flexible, parsimonious model of age-specific mortality for countries with generalized HIV epidemics. Combined with the outputs of existing epidemiological and demographic models, this model makes it possible to project future age-specific mortality profiles and number of deaths for countries with generalized HIV epidemics.

Using HIV-attributable mortality to assess the impact of antiretroviral therapy on adult mortality in rural Tanzania

Background

The Tanzanian national HIV care and treatment programme has provided free antiretroviral therapy (ART) to HIV-positive persons since 2004. ART has been available to participants of the Kisesa open cohort study since 2005, but data to 2007 showed a slow uptake of ART and a modest impact on mortality. Additional data from the 2010 HIV serological survey provide an opportunity to update the estimated impact of ART in this setting.

Methods

The Kisesa Health and Demographic Surveillance Site (HDSS) has collected HIV serological data and demographic data, including verbal autopsy (VA) interviews since 1994. Serological data to the end of 2010 were used to make two estimates of HIV-attributable mortality, the first among HIV positives using the difference in mortality between HIV positives and HIV negatives, and the second in the population using the difference between the observed mortality rate in the whole population and the mortality rate among the HIV negatives. Four time periods (1994–1999, 2000–2004, 2005–2007, and 2008–2010) were used and HIV-attributable mortality estimates were analysed in detail for trends over time. A computer algorithm, InterVA-4, was applied to VA data to estimate the HIV-attributable mortality for the population, and this was compared to the estimates from the serological survey data.

Results

Among HIV-positive adults aged 45–59 years, high mortality rates were observed across all time periods in both males and females. In HIV-positive men, the HIV-attributable mortality was 91.6% (95% confidence interval (CI): 84.6%–95.3%) in 2000–2004 and 86.3% (95% CI: 71.1%–93.3%) in 2008–2010, while among women, the HIV-attributable mortality was 87.8% (95% CI: 71.1%–94.3%) in 2000–2004 and 85.8% (95% CI: 59.6%–94.4%) in 2008–2010. In the whole population, using the serological data, the HIV-attributable mortality among men aged 30–44 years decreased from 57.2% (95% CI: 46.9%–65.3%) in 2000–2004 to 36.5% (95% CI: 18.8%–50.1%) in 2008–2010, while among women the corresponding decrease was from 57.3% (95% CI: 49.7%–63.6%) to 38.7% (95% CI: 27.4%–48.2%). The HIV-attributable mortality in the population using estimates from the InterVA model was lower than that from HIV sero-status data in the period prior to ART, but slightly higher once ART became available.

Discussion

In the Kisesa HDSS, ART availability corresponds with a decline in adult overall mortality, although not as large as expected. Using InterVA to estimate HIV-attributable mortality showed smaller changes in HIV-related mortality following ART availability than the serological results.

The Age Pattern of Increases in Mortality Affected by HIV: Bayesian Fit of the Heligman-Pollard Model to Data from the Agincourt HDSS Field Site in Rural Northeast South Africa

BACKGROUND

We investigate the sex-age-specific changes in the mortality of a prospectively monitored rural population in South Africa. We quantify changes in the age pattern of mortality in a parsimonious way by estimating the eight parameters of the Heligman-Pollard (HP) model of age-specific mortality. In its traditional form this model is difficult to fit and does not account for uncertainty.

OBJECTIVE

1. To quantify changes in the sex-age pattern of mortality experienced by a population with endemic HIV. 2. To develop and demonstrate a robust Bayesian estimation method for the HP model that accounts for uncertainty.

METHODS

Bayesian estimation methods are adapted to work with the HP model. Temporal changes in parameter values are related to changes in HIV prevalence.

RESULTS

Over the period when the HIV epidemic in South Africa was growing, mortality in the population described by our data increased profoundly with losses of life expectancy of ~15 years for both males and females. The temporal changes in the HP parameters reflect in a parsimonious way the changes in the age pattern of mortality. We develop a robust Bayesian method to estimate the eight parameters of the HP model and thoroughly demonstrate it.

CONCLUSIONS

Changes in mortality in South Africa over the past fifteen years have been profound. The HP model can be fit well using Bayesian methods, and the results can be useful in developing a parsimonious description of changes in the age pattern of mortality.

COMMENTS

The motivating aim of this work is to develop new methods that can be useful in applying the HP eight-parameter model of age-specific mortality. We have done this and chosen an interesting application to demonstrate the new methods.

Analytic review of modeling studies of ARV Based PrEP interventions reveals strong influence of drug-resistance assumptions on the population-level effectiveness

Background

Four clinical trials have shown that oral and topical pre-exposure prophylaxis (PrEP) based on tenofovir may be effective in preventing HIV transmission. The expected reduction in HIV transmission and the projected prevalence of drug resistance due to PrEP use vary significantly across modeling studies as a result of the broad spectrum of assumptions employed. Our goal is to quantify the influence of drug resistance assumptions on the predicted population-level impact of PrEP.

Methods

All modeling studies which evaluate the impact of oral or topical PrEP are reviewed and key assumptions regarding mechanisms of generation and spread of drug-resistant HIV are identified. A dynamic model of the HIV epidemic is developed to assess and compare the impact of oral PrEP using resistance assumptions extracted from published studies. The benefits and risks associated with ten years of PrEP use are evaluated under identical epidemic, behavioral and intervention conditions in terms of cumulative fractions of new HIV infections prevented, resistance prevalence among those infected with HIV, and fractions of infections in which resistance is transmitted.

Results

Published models demonstrate enormous variability in resistance-generating assumptions and uncertainty in parameter values. Depending on which resistance parameterization is used, a resistance prevalence between 2% and 44% may be expected if 50% efficacious oral PrEP is used consistently by 50% of the population over ten years. We estimated that resistance may be responsible for up to a 10% reduction or up to a 30% contribution to the fraction of prevented infections predicted in different studies.

Conclusions

Resistance assumptions used in published studies have a strong influence on the projected impact of PrEP. Modelers and virologists should collaborate toward clarifying the set of resistance assumptions biologically relevant to the PrEP products which are already in use or soon to be added to the arsenal against HIV.

Population-level benefits from providing effective HIV prevention means to pregnant women in high prevalence settings

BACKGROUND

HIV prevalence among pregnant women in Southern Africa is extremely high. Epidemiological studies suggest that pregnancy increases the risk of HIV sexual acquisition and that HIV infections acquired during pregnancy carry higher risk of mother-to-child transmission (MTCT). We analyze the potential benefits from extending the availability of effective microbicide to pregnant women (in addition to non-pregnant women) in a wide-scale intervention.

METHODS AND FINDINGS

A transmission dynamic model was designed to assess the impact of microbicide use in high HIV prevalence settings and to estimate proportions of new HIV infections, infections acquired during pregnancy, and MTCT prevented over 10 years. Our analysis suggests that consistent use of microbicide with 70% efficacy by 60% of non-pregnant women may prevent approximately 40% and 15% of new infections in women and men respectively over 10 years, assuming no additional increase in HIV risk to either partner during pregnancy (RR(HIV/preg) = 1). It may also prevent 8-15% MTCT depending on the increase in MTCT risk when HIV is acquired during pregnancy compared to before pregnancy (RRMTCT/preg). Extending the microbicides use during pregnancy may improve the effectiveness of the intervention by 10% (RR(HIV/preg) = 1) to 25% (RR(HIV/preg) = 2) and reduce the number of HIV infections acquired during pregnancy by 40% to 70% in different scenarios. It may add between 6% (RR(HIV/preg) = 1, RR(MTCT/preg) = 1) and 25% (RR(HIV/preg) = 2, RR(MTCT/preg) = 4) to the reduction in the residual MTCT.

CONCLUSION

Providing safe and effective microbicide to pregnant women in the context of wide-scale interventions would be desirable as it would increase the effectiveness of the intervention and significantly reduce the number of HIV infections acquired during pregnancy. The projected benefits from covering pregnant women by the HIV prevention programs is more substantial in communities in which the sexual risk during pregnancy is elevated.

Effect of HIV infection on pregnancy-related mortality in sub-Saharan Africa: secondary analyses of pooled community-based data from the network for Analysing Longitudinal Population-based HIV/AIDS data on Africa (ALPHA)

BACKGROUND

Model-based estimates of the global proportions of maternal deaths that are in HIV-infected women range from 7% to 21%, and the effects of HIV on the risk of maternal death is highly uncertain. We used longitudinal data from the Analysing Longitudinal Population-based HIV/AIDS data on Africa (ALPHA) network to estimate the excess mortality associated with HIV during pregnancy and the post-partum period in sub-Saharan Africa.

METHODS

The ALPHA network pooled data gathered between June, 1989 and April, 2012 in six community-based studies in eastern and southern Africa with HIV serological surveillance and verbal-autopsy reporting. Deaths occurring during pregnancy and up to 42 days post partum were defined as pregnancy related. Pregnant or post-partum person-years were calculated for HIV-infected and HIV-uninfected women, and HIV-infected to HIV-uninfected mortality rate ratios and HIV-attributable rates were compared between pregnant or post-partum women and women who were not pregnant or post partum.

FINDINGS

138,074 women aged 15-49 years contributed 636,213 person-years of observation. 49,568 women had 86,963 pregnancies. 6760 of these women died, 235 of them during pregnancy or the post-partum period. Mean prevalence of HIV infection across all person-years in the pooled data was 17.2% (95% CI 17.0-17.3), but 60 of 118 (50.8%) of the women of known HIV status who died during pregnancy or post partum were HIV infected. The mortality rate ratio of HIV-infected to HIV-uninfected women was 20.5 (18.9-22.4) in women who were not pregnant or post partum and 8.2 (5.7-11.8) in pregnant or post-partum women. Excess mortality attributable to HIV was 51.8 (47.8-53.8) per 1000 person-years in women who were not pregnant or post partum and 11.8 (8.4-15.3) per 1000 person-years in pregnant or post-partum women.

INTERPRETATION

HIV-infected pregnant or post-partum women had around eight times higher mortality than did their HIV-uninfected counterparts. On the basis of this estimate, we predict that roughly 24% of deaths in pregnant or post-partum women are attributable to HIV in sub-Saharan Africa, suggesting that safe motherhood programmes should pay special attention to the needs of HIV-infected pregnant or post-partum women.

FUNDING

Wellcome Trust, Health Metrics Network (WHO).

Mathematical insights in evaluating state dependent effectiveness of HIV prevention interventions

Mathematical models have been used to simulate HIV transmission and to study the use of preexposure prophylaxis (PrEP) for HIV prevention. Often a single intervention outcome over 10 years has been used to evaluate the effectiveness of PrEP interventions. However, different metrics express a wide variation over time and often disagree in their forecast on the success of the intervention. We develop a deterministic mathematical model of HIV transmission and use it to evaluate the public-health impact of oral PrEP interventions. We study PrEP effectiveness with respect to different evaluation methods and analyze its dynamics over time. We compare four traditional indicators, based on cumulative number or fractions of infections prevented, on reduction in HIV prevalence or incidence and propose two additional methods, which estimate the burden of the epidemic to the public-health system. We investigate the short and long term behavior of these indicators and the effects of key parameters on the expected benefits from PrEP use. Our findings suggest that public-health officials considering adopting PrEP in HIV prevention programs can make better informed decisions by employing a set of complementing quantitative metrics.

Impact of Pill Sharing on Drug Resistance Due to a Wide-Scale Oral Prep Intervention in Generalized Epidemics

BACKGROUND

The first antiretroviral drug (Truvada) to be used as a pre-exposure prophylaxis (PrEP) in preventing HIV transmission is about to be approved. Behavioral studies suggest that a portion of users may share anti-retroviral drugs with sex partners, family, or friends. Pill sharing will decrease PrEP efficacy and adherence level, and potentially create an environment favorable for the development of drug resistance. We aim to evaluate the potential impact of pill sharing on the PrEP effectiveness and on the rates of drug-resistance development in heterosexual populations.

METHODS

A transmission dynamic model was used to assess the population-level impact of oral PrEP. The fractions of new HIV infections prevented (CPF), drug resistance prevalence and the proportion of new infections in which drug-resistant HIV is transmitted (TDR) are evaluated over fixed time periods. The influence of different factors on CPF and TDR is studied through simulations, using epidemic parameters representative of the countries in Sub-Saharan Africa.

RESULTS

Without pill sharing, a 70% efficacious PrEP used consistently by 60% of uninfected individuals prevents 52.8% (95% CI 49.4%-56.4%) of all new HIV infections over ten years with drug-resistant HIV transmitted in 2.2% of the new infections. Absolute CPF may vary by 9% if up to 20% of the users share PrEP while the level of TDR and total resistance prevalence may increase by up to 6-fold due to pill sharing in some intervention scenarios.

CONCLUSION

Pill sharing may increase the PrEP coverage level achieved in the population but it also affects the PrEP efficacy for the users who do not follow the prescribed schedule. More importantly, it creates a pool of untracked users who remain unreached by the effort to avoid sub-optimal PrEP usage by infected people. This increases substantially the potential risk of drug resistance in the population.

Age-specific and sex-specific mortality in 187 countries, 1970-2010: a systematic analysis for the Global Burden of Disease Study 2010

BACKGROUND

Estimation of the number and rate of deaths by age and sex is a key first stage for calculation of the burden of disease in order to constrain estimates of cause-specific mortality and to measure premature mortality in populations. We aimed to estimate life tables and annual numbers of deaths for 187 countries from 1970 to 2010.

METHODS

We estimated trends in under-5 mortality rate (children aged 0-4 years) and probability of adult death (15-59 years) for each country with all available data. Death registration data were available for more than 100 countries and we corrected for undercount with improved death distribution methods. We applied refined methods to survey data on sibling survival that correct for survivor, zero-sibling, and recall bias. We separately estimated mortality from natural disasters and wars. We generated final estimates of under-5 mortality and adult mortality from the data with Gaussian process regression. We used these results as input parameters in a relational model life table system. We developed a model to extrapolate mortality to 110 years of age. All death rates and numbers have been estimated with 95% uncertainty intervals (95% UIs).

FINDINGS

From 1970 to 2010, global male life expectancy at birth increased from 56·4 years (95% UI 55·5-57·2) to 67·5 years (66·9-68·1) and global female life expectancy at birth increased from 61·2 years (60·2-62·0) to 73·3 years (72·8-73·8). Life expectancy at birth rose by 3-4 years every decade from 1970, apart from during the 1990s (increase in male life expectancy of 1·4 years and in female life expectancy of 1·6 years). Substantial reductions in mortality occurred in eastern and southern sub-Saharan Africa since 2004, coinciding with increased coverage of antiretroviral therapy and preventive measures against malaria. Sex-specific changes in life expectancy from 1970 to 2010 ranged from gains of 23-29 years in the Maldives and Bhutan to declines of 1-7 years in Belarus, Lesotho, Ukraine, and Zimbabwe. Globally, 52·8 million (95% UI 51·6-54·1 million) deaths occurred in 2010, which is about 13·5% more than occurred in 1990 (46·5 million [45·7-47·4 million]), and 21·9% more than occurred in 1970 (43·3 million [42·2-44·6 million]). Proportionally more deaths in 2010 occurred at age 70 years and older (42·8% in 2010 vs 33·1% in 1990), and 22·9% occurred at 80 years or older. Deaths in children younger than 5 years declined by almost 60% since 1970 (16·4 million [16·1-16·7 million] in 1970 vs 6·8 million [6·6-7·1 million] in 2010), especially at ages 1-59 months (10·8 million [10·4-11·1 million] in 1970 vs 4·0 million [3·8-4·2 million] in 2010). In all regions, including those most affected by HIV/AIDS, we noted increases in mean ages at death.

INTERPRETATION

Despite global and regional health crises, global life expectancy has increased continuously and substantially in the past 40 years. Yet substantial heterogeneity exists across age groups, among countries, and over different decades. 179 of 187 countries have had increases in life expectancy after the slowdown in progress in the 1990s. Efforts should be directed to reduce mortality in low-income and middle-income countries. Potential underestimation of achievement of the Millennium Development Goal 4 might result from limitations of demographic data on child mortality for the most recent time period. Improvement of civil registration system worldwide is crucial for better tracking of global mortality.

FUNDING

Bill & Melinda Gates Foundation.

Intergenerational transfers in the era of HIV/AIDS: Evidence from rural Malawi

BACKGROUND

Intergenerational transfer patterns in sub-Saharan Africa are poorly understood, despite the alleged importance of support networks to ameliorate the complex implications of the HIV/AIDS epidemic for families.

OBJECTIVE

There is a considerable need for research on intergenerational support networks and transfers to better understand the mechanisms through which extended families cope with the HIV/AIDS epidemic and potentially alleviate some of its consequences in sub-Saharan Africa, and to comprehend how transfers respond-or not-to perceptions about own and other family members' health.

METHODS

Using the 2008 round of the Malawi Longitudinal Study of Families and Health (MLSFH), we estimate the age patterns and the multiple directions of financial and non-financial transfer flows in rural Malawi-from prime-aged respondents to their elderly parents and adult children age 15 and up. We also estimate the social, demographic and economic correlates of financial and non-financial transfers of financial intergenerational transfers in this context.

RESULTS AND CONCLUSIONS

Our findings are that: (1) intergenerational financial and non-financial transfers are widespread and a key characteristic of family relationships in rural Malawi; (2) downward and upward transfers are importantly constrained and determined by the availability of transfer partners (parents or adult children); (3) financial net transfers are strongly age-patterned and the middle generations are net-providers of transfers; (4) non-financial transfers are based on mutual assistance rather than reallocation of resources; and (5) intergenerational transfers are generally not related to health status, including HIV positive status.

The effect of antiretroviral therapy provision on all-cause, AIDS and non-AIDS mortality at the population level--a comparative analysis of data from four settings in Southern and East Africa

OBJECTIVE

To provide a broad and up-to-date picture of the effect of antiretroviral therapy (ART) provision on population-level mortality in Southern and East Africa.

METHODS

Data on all-cause, AIDS and non-AIDS mortality among 15-59 year olds were analysed from demographic surveillance sites (DSS) in Karonga (Malawi), Kisesa (Tanzania), Masaka (Uganda) and the Africa Centre (South Africa), using Poisson regression. Trends over time from up to 5 years prior to ART roll-out, to 4-6 years afterwards, are presented, overall and by age and sex. For Masaka and Kisesa, trends are analysed separately for HIV-negative and HIV-positive individuals. For Karonga and the Africa Centre, trends in AIDS and non-AIDS mortality are analysed using verbal autopsy data.

RESULTS

For all-cause mortality, overall rate ratios (RRs) comparing the period 2-6 years following ART roll-out with the pre-ART period were 0.58 (5.9 vs. 10.2 deaths per 1000 person-years) in Karonga, 0.79 (7.2 vs. 9.1 deaths per 1000 person-years) in Kisesa, 0.61 (6.7 compared with 11.0 deaths per 1000 person-years) in Masaka and 0.79 (14.8 compared with 18.6 deaths per 1000 person-years) in the Africa Centre DSS. The mortality decline was seen only in HIV-positive individuals/AIDS mortality, with no decline in HIV-negative individuals/non-AIDS mortality. Less difference was seen in Kisesa where ART uptake was lower.

CONCLUSIONS

Falls in all-cause mortality are consistent with ART uptake. The largest falls occurred where ART provision has been decentralised or available locally, suggesting that this is important.

HIV and malaria interactions: where do we stand?

Reversing the spread of HIV infection and the incidence of malaria constitute two of the Millenium Development Goals. However, despite recent achievements, both diseases still entail global heath problems. Furthermore, their overlapping geographical distribution raises concerns and challenges for potential immunological, clinical and therapeutic interactions. It has been reported that HIV infection increases malaria susceptibility and reduces the efficacy of antimalarial drugs. On the other hand, the effect of malaria on HIV-infected individuals has also been explored, with the parasitic infection increasing the risk of HIV disease progression and mother-to-child transmission of HIV. The spread of malaria and parasite resistance to antimalarials could also be accelerated by HIV-associated immunosuppresion. Current knowledge of the epidemiological, clinical, immunological and therapeutic interactions of the two diseases is reviewed in this article. We focus on the latest available data, pointing out key future research areas and challenges of the field.

Burial surveillance detected significant reduction in HIV--related deaths in Addis Ababa, Ethiopia

OBJECTIVE

To determine the level of HIV-related mortality reduction after the introduction of large-scale antiretroviral therapy (ART) using a burial surveillance system coupled with verbal autopsy (VA) in Addis Ababa, Ethiopia.

METHODS

Prospective burial surveillance was established in 2001 at cemeteries in Addis Ababa. VA interviews were periodically conducted on a random sample of adult burials registered between 2001 and 2009. Independent physicians reviewed the completed VA questionnaires and assigned underlying causes of death. The period before 2005 was defined as pre-ART and that since 2005 as the ART era. HIV-specific mortality fractions were calculated by age, sex and year of burial to examine the mortality trends before and during the ART era.

RESULTS

Of the 4239 VA physician diagnoses, 1087 (25.6%) were ascribed to HIV-related deaths. HIV-related deaths in 2009 were 33% fewer than in 2001. The proportion of HIV-related deaths was reduced from 44.0% in the pre-ART period to 20.0% in the ART era. Mortality in women (36.7%) declined more than in men (30%). A marked reduction in HIV-specific mortality was observed in the age group 30-39 years (from 69.1% pre-ART to 46.8% during ART era) compared to 20-29 (from 60.5% pre-ART to 41.0% during ART) and 40-49 year olds (49.7%) pre-ART to 34.4% during ART provision).

CONCLUSION

Burial surveillance combined with VA demonstrated a significant reduction in HIV-related deaths during the provision of free ART. Replication of burial surveillance is recommended in similar settings, where a vital registration system is non-existent, to track large-scale population-level interventions.

Modeling the gender-specific impact of vaginal microbicides on HIV transmission

Vaginal microbicides (VMB) are currently among the few women-initiated biomedical interventions for preventing heterosexual transmission of HIV. In this paper we use a deterministic model of HIV transmission to assess the public-health benefits of a VMB intervention and evaluate its gender-specific impact over short (initial) and extended periods of time. We define two distinct quantitative benefit ratios (QBRs) based on infections prevented in men and women to create and study regions of male advantage in different parameter spaces. Our analysis exposes complicated temporal correlations between the QBRs and series of pre-intervention (e.g., HIV acquisition risks per act) and intervention parameters (e.g., VMB efficacy mechanisms, rates of resistance development and reversion) and indicates that different QBRs may often disagree on the gender distribution of the benefits from a VMB intervention. We also outline the strong influence of some modeling assumptions on the reported results and conclude that the assessment of VMB and other biomedical interventions must be based on more comprehensive analyses than calculations of infections prevented over a fixed period of time.

More on the cohort-component model of population projection in the context of HIV/AIDS: A Leslie matrix representation and new estimates

This article presents an extension of the cohort-component model of population projection (CCMPP) first formulated by Heuveline (2003) that is capable of modeling a population affected by HIV. Heuveline proposes a maximum likelihood approach to estimate the age profile of HIV incidence that produced the HIV epidemics in East Africa during the 1990s. We extend this work by developing the Leslie matrix representation of the CCMPP, which greatly facilitates the implementation of the model for parameter estimation and projection. The Leslie matrix also contains information about the stable tendencies of the corresponding population, such as the stable age distribution and time to stability. Another contribution of this work is that we update the sources of data used to estimate the parameters, and use these data to estimate a modified version of the CCMPP that includes (estimated) parameters governing the survival experience of the infected population. A further application of the model to a small population with high HIV prevalence in rural South Africa is presented as an additional demonstration. This work lays the foundation for development of more robust and flexible Bayesian estimation methods that will greatly enhance the utility of this and similar models.

HIV-infected former plasma donors in rural Central China: from infection to survival outcomes, 1985-2008

Background

The HIV epidemic among former plasma donors (FPDs) in rural Central China in the early-mid 1990s is likely the largest known HIV-infected cohort in the world related to commercial plasma donation but has never been fully described. The objectives of this study are to estimate the timing and geographic spread of HIV infection in this cohort and to demonstrate the impact of antiretroviral therapy on survival outcomes.

Methodology/Principal Findings

HIV-infected FPDs were identified using the national HIV epidemiology and treatment databases. Locations of subjects were mapped. Dates of infection and survival were estimated using the midpoint date between initial-final plasma donation dates from 1985–2008 among those with plasma donation windows ≤2 years. Among 37084 FPDs in the two databases, 36110 were included. 95% were located in focal areas of Henan Province and adjacent areas of surrounding provinces. Midpoint year between initial-final plasma donation dates was 1994 among FPDs with known donation dates. Median survival from infection to AIDS was 11.8 years and, among those not treated, 1.6 years from AIDS to death. Among those on treatment, 71% were still alive after five years. Using Cox proportional hazard modeling, untreated AIDS patients were 4.9 times (95% confidence interval 4.6–5.2) more likely to die than those on treatment.

Conclusions/Significance

The epidemic of HIV-infected FPD in China was not widespread throughout China but rather was centered in Henan Province and the adjacent areas of surrounding provinces. Even in these areas, infections were concentrated in focal locations. Overall, HIV infections in this cohort peaked in 1994, with median survival of 13.4 years from infection to death among those not treated. Among AIDS patients on treatment, 71% were still alive after five years.

Verbal autopsy can consistently measure AIDS mortality: a validation study in Tanzania and Zimbabwe

BACKGROUND

Verbal autopsy is currently the only option for obtaining cause of death information in most populations with a widespread HIV/AIDS epidemic.

METHODS

With the use of a data-driven algorithm, a set of criteria for classifying AIDS mortality was trained. Data from two longitudinal community studies in Tanzania and Zimbabwe were used, both of which have collected information on the HIV status of the population over a prolonged period and maintained a demographic surveillance system that collects information on cause of death through verbal autopsy. The algorithm was then tested in different times (two phases of the Zimbabwe study) and different places (Tanzania and Zimbabwe).

RESULTS

The trained algorithm, including nine signs and symptoms, performed consistently based on sensitivity and specificity on verbal autopsy data for deaths in 15-44-year-olds from Zimbabwe phase I (sensitivity 79%; specificity 79%), phase II (sensitivity 83%; specificity 75%) and Tanzania (sensitivity 75%; specificity 74%) studies. The sensitivity dropped markedly for classifying deaths in 45-59-year-olds.

CONCLUSIONS

Verbal autopsy can consistently measure AIDS mortality with a set of nine criteria. Surveillance should focus on deaths that occur in the 15-44-year age group for which the method performs reliably. Addition of a handful of questions related to opportunistic infections would enable other widely used verbal autopsy tools to apply this validated method in areas for which HIV testing and hospital records are unavailable or incomplete.

Who will Benefit from a Wide-Scale Introduction of Vaginal Microbicides in Developing Countries?

Vaginal microbicides (VMB) are currently among the few biomedical interventions designed to help women reduce their risk of acquiring HIV infection. However, the microbicide containing antiretroviral (ARV-VMB) may lead to the development of antiretroviral resistance and could paradoxically become more beneficial to men at the population level. We developed a mathematical model to study the impact of a wide-scale population usage of VMB in a heterosexual population. Gender ratios of prevented infections and prevalence reduction are evaluated in 63 different intervention schedules including continuous and interrupted ARV-VMB use by HIV-positive women. The influence of different factors on population-level benefits is also studied through Monte Carlo simulations using parameters sampled from primary ranges representative of developing countries. Our analysis indicates that women are more likely than men to benefit from ARV-VMB use since 78-80% of the total 63,000 simulations investigated (under different parameter sets) showed a female advantage whether benefit is measured as cumulative number of infections prevented, the percentage of cumulative infections prevented, or the expected reduction in prevalence. Stratified analysis by scenarios indicates that the likelihood of a male advantage with respect to the fractions of prevented infections varies from 6% to 49% among the scenarios. It is substantial only if the risk of systemic absorption and development of resistance to ARV-VMB is high and the HIV-positive women use VMB indefinitely without interruption. Therefore, the use of ARV-VMB, with successful control measures restricting usage by HIV-positive women, is still very much a female prevention tool.

Marital strategies for regulating exposure to HIV

In a setting where the transmission of HIV occurs primarily through heterosexual contact and where no cure or vaccine is available, behavioral change is imperative for containing the epidemic. Abstinence, faithfulness, and condom use most often receive attention in this regard. In contrast, this article treats marriage as a resource for HIV risk management via mechanisms of positive selection (partner choice) and negative selection (divorce of an adulterous spouse). Retrospective marriage histories and panel data provide the evidence for this study and results indicate that men and women in Malawi increasingly turned to union-based risk-avoidance strategies during the period that the threat of HIV/AIDS materialized. Although both sexes strategize in a similar fashion, men are better equipped than women to deploy these strategies to their advantage. The article concludes with reflections on the long-term and population-level implications of these coping mechanisms.

Population-level effect of HIV on adult mortality and early evidence of reversal after introduction of antiretroviral therapy in Malawi

BACKGROUND

Malawi, which has about 80,000 deaths from AIDS every year, made free antiretroviral therapy available to more than 80 000 patients between 2004 and 2006. We aimed to investigate mortality in a population before and after the introduction of free antiretroviral therapy, and therefore to assess the effects of such programmes on survival at the population level.

METHODS

We used a demographic surveillance system to measure mortality in a population of 32,000 in northern Malawi, from August, 2002, when free antiretroviral therapy was not available in the study district, until February, 2006, 8 months after a clinic opened. Causes of death were established through verbal autopsies (retrospective interviews). Patients who registered for antiretroviral therapy at the clinic were identified and linked to the population under surveillance. Trends in mortality were analysed by age, sex, cause of death, and zone of residence.

FINDINGS

Before antiretroviral therapy became available in June, 2005, mortality in adults (aged 15-59 years) was 9.8 deaths for 1000 person-years of observation (95% CI 8.9-10.9). The probability of dying between the ages of 15 and 60 years was 43% (39-49) for men and 43% (38-47) for women; 229 of 352 deaths (65.1%) were attributed to AIDS. 8 months after the clinic that provided antiretroviral therapy opened, 107 adults from the study population had accessed treatment, out of an estimated 334 in need of treatment. Overall mortality in adults had decreased by 10% from 10.2 to 8.7 deaths for 1000 person-years of observation (adjusted rate ratio 0.90, 95% CI 0.70-1.14). Mortality was reduced by 35% (adjusted rate ratio 0.65, 0.46-0.92) in adults near the main road, where mortality before antiretroviral therapy was highest (from 13.2 to 8.5 deaths per 1000 person-years of observation before and after antiretroviral therapy). Mortality in adults aged 60 years or older did not change.

INTERPRETATION

Our findings of a reduction in mortality in adults aged between 15 and 59 years, with no change in those older than 60 years, suggests that deaths from AIDS were averted by the rapid scale-up of free antiretroviral therapy in rural Malawi, which led to a decline in adult mortality that was detectable at the population level.

Estimating incidence from prevalence in generalised HIV epidemics: methods and validation

BACKGROUND

HIV surveillance of generalised epidemics in Africa primarily relies on prevalence at antenatal clinics, but estimates of incidence in the general population would be more useful. Repeated cross-sectional measures of HIV prevalence are now becoming available for general populations in many countries, and we aim to develop and validate methods that use these data to estimate HIV incidence.

METHODS AND FINDINGS

Two methods were developed that decompose observed changes in prevalence between two serosurveys into the contributions of new infections and mortality. Method 1 uses cohort mortality rates, and method 2 uses information on survival after infection. The performance of these two methods was assessed using simulated data from a mathematical model and actual data from three community-based cohort studies in Africa. Comparison with simulated data indicated that these methods can accurately estimates incidence rates and changes in incidence in a variety of epidemic conditions. Method 1 is simple to implement but relies on locally appropriate mortality data, whilst method 2 can make use of the same survival distribution in a wide range of scenarios. The estimates from both methods are within the 95% confidence intervals of almost all actual measurements of HIV incidence in adults and young people, and the patterns of incidence over age are correctly captured.

CONCLUSIONS

It is possible to estimate incidence from cross-sectional prevalence data with sufficient accuracy to monitor the HIV epidemic. Although these methods will theoretically work in any context, we have able to test them only in southern and eastern Africa, where HIV epidemics are mature and generalised. The choice of method will depend on the local availability of HIV mortality data.

Nutritional status, psychological well-being and the quality of life of AIDS orphans in rural Henan Province, China

OBJECTIVE

To assess the influence of orphanhood due to AIDS on children's nutritional status, psychological well-being and life quality, and to explore appropriate intervention strategies in China.

METHODS

In 2005, 186 children aged 8-15 years (93 AIDS orphans and 93 non-orphans) from a rural area of Henan Province were surveyed in a cross-sectional and matched pairs study on nutritional status, psychological health and life quality.

RESULTS

We found no compelling evidence for poorer nutritional status in orphans. The nutritional status of both orphans and non-orphans was extremely poor according to the prevalence of stunting, underweight, wasting and anaemia. Depression, low self-esteem and lower quality of life were more frequent in orphans. These differences mainly existed in boys' groups. No significant differences were found between paternal, maternal and double orphans, or orphans in orphanages or extended families. Regression analysis revealed that orphanhood leads to low self-esteem and more depression which contributes to lower quality of life and mediates the association between orphanhood and quality of life.

CONCLUSION

The high prevalence of poor nutritional status indicates that basic material needs of children, including AIDS orphans, are not met in rural China. Psychological problems were prominent among orphans and had become the most important contributor of lower life quality. Boys were at least as vulnerable as girls. The living conditions of all children in rural China must be improved; school-based care and support are crucial and would be a cost-effective way to improve the overall life quality of AIDS orphans.

Survival after HIV infection in the pre-antiretroviral therapy era in a rural Tanzanian cohort

BACKGROUND

Survival patterns after HIV infection in African populations in the era before antiretroviral therapy (ART) form an important baseline for measuring future successes of treatment programmes. Few studies have followed seroconverters for 10 or more years to describe such patterns.

METHODS

The Kisesa open cohort study conducted four rounds of village-based HIV testing and 20 rounds of household-based demographic surveillance between 1994 and 2006. Approximate infection dates were established for individual seroconverters by allocating a date between the last negative and first positive test. Person-years lived post-infection were computed, allowing for left truncation and right censoring, and Kaplan-Meier survival functions were constructed, truncating the analysis at the start of 2005 when ART first became available in the community. Weibull models were fitted to estimate median survival time, and parametric regression methods were used to investigate the influence of sex and age at infection.

RESULTS

A total of 369 seroconverters were identified, providing 890 person-years of follow-up during which 44 deaths were observed. The Kaplan-Meier function showed 67% surviving 9 years post-infection, and the overall predicted median survival was 11.5 years. Survival was strongly related to age at infection (hazard ratio 1.06 for each additional year of age, and weakly to sex. A strong effect of age was evident even after allowing for mortality from non-HIV-related causes using cause deletion methods to estimate net mortality.

CONCLUSION

The survival of HIV-infected individuals was comparable to that reported in developed country studies before the introduction of HAART. Survival patterns in Kisesa are marginally more favourable than those reported in cohort studies in Uganda.

Cause of death and presence of respiratory disease at autopsy in an HIV-1 seroconversion cohort of southern African gold miners

OBJECTIVES

To describe causes of death and respiratory infections in HIV-infected miners in the pre-antiretroviral era, by duration of HIV infection.

DESIGN

A retrospective cohort of 1950 gold miners with known dates of HIV seroconversion and 6164 HIV-negative miners was followed from the early 1990s to 2002.

METHODS

Causes of death were available from multiple sources: personnel records, clinical records, death certificates and autopsies of cardiorespiratory organs performed for compensation purposes.

RESULTS

Causes of death were known for 279 of 308 HIV-positive (91%) and 234 of 254 HIV-negative (92%) men who died while employed or within 6 months of leaving employment. The mortality rate from unnatural causes was similar in HIV-positive and HIV-negative miners and by duration of HIV infection. Among deaths from natural causes, 87% in HIV-positive and 41% in HIV-negative individuals were caused by infection (P < 0.001); 47% of HIV-positive and 26% of HIV-negative individuals had tuberculosis. The proportion of deaths from natural causes with any infection, or with specific infections (tuberculosis, cryptococcus, pneumocystis), did not vary with the duration of HIV infection. Autopsies were performed on 29% of men who died from natural causes: 83% of HIV-positive and 37% of HIV-negative men had respiratory infections (P < 0.001), half of which were clinically undiagnosed.

CONCLUSION

Tuberculosis was the leading cause of death in HIV-positive and negative men who died from natural causes. Although the mortality rate from natural causes increased greatly with the duration of HIV infection, the pattern of disease hardly changed, suggesting that slow and fast progressors succumb to the same range of diseases.

Age-specific mortality patterns in HIV-infected individuals: a comparative analysis of African community study data

OBJECTIVES

Describe age-specific mortality patterns of HIV-infected adults in African communities before introduction of HAART.

METHODS

Mortality data (deaths and person-years observed) for HIV-positive subjects aged 15-65 from six African community studies in five different countries were pooled, combining information from 1793 seroconverters and 8534 HIV positive when first tested. Age-specific mortality hazards were modelled using parametric regression based on the Weibull distribution, to investigate effects of sex, and site-specific measures of mean age at incidence, crude mortality rate of uninfected, and measures of epidemic maturity.

RESULTS

The combined studies yielded a total of 31 777 person-years of observation for HIV-positive subjects, during which time 2602 deaths were recorded. Mortality rates rose almost linearly with age, from below 50/1000 at ages < 20 years, up to 150/1000 at 50 years +. There was no significant difference between men and women in level or age pattern of mortality. Weibull regression analysis suggested that intersite variation could be explained by HIV prevalence trend, and by the ratio of HIV proportional mortality to current HIV prevalence. A model representation was constructed with a common age pattern of mortality, but allowing the level to be adjusted by specifying HIV prevalence indicators.

CONCLUSION

The linear age trend of mortality in HIV-infected populations was satisfactorily represented by a Weibull function providing a parametric model adaptable for representing different levels of HIV-related mortality. This model might be simpler to use in demographic projections of HIV-affected populations than models based on survival post-infection.

Time from HIV seroconversion to death: a collaborative analysis of eight studies in six low and middle-income countries before highly active antiretroviral therapy

OBJECTIVES

To estimate survival patterns after HIV infection in adults in low and middle-income countries.

DESIGN

An analysis of pooled data from eight different studies in six countries.

METHODS

HIV seroconverters were included from eight studies (three population-based, two occupational, and three clinic cohorts) if they were at least 15 years of age, and had no more than 4 years between the last HIV-negative and subsequent HIV-positive test. Four strata were defined: East African cohorts; South African miners cohort; Thai cohorts; Haitian clinic cohort. Kaplan-Meier functions were used to estimate survival patterns, and Weibull distributions were used to model and extend survival estimates. Analyses examined the effect of site, age, and sex on survival.

RESULTS

From 3823 eligible seroconverters, 1079 deaths were observed in 19 671 person-years of follow-up. Survival times varied by age and by study site. Adjusting to age 25-29 years at seroconversion, the median survival was longer in South African miners: 11.6 years [95% confidence interval (CI) 9.8-13.7] and East African cohorts: 11.1 years (95% CI 8.7-14.2) than in Haiti: 8.3 years (95% CI 3.2-21.4) and Thailand: 7.5 years (95% CI 5.4-10.4). Survival was similar for men and women, after adjustment for age at seroconversion and site.

CONCLUSION

Without antiretroviral therapy, overall survival after HIV infection in African cohorts was similar to survival in high-income countries, with a similar pattern of faster progression at older ages at seroconversion. Survival appears to be significantly worse in Thailand where other, unmeasured factors may affect progression.

The impact of AIDS on government service delivery: the case of the Zambia Wildlife Authority

BACKGROUND

The loss of working-aged adults to HIV/AIDS has been shown to increase the costs of labor to the private sector in Africa. There is little corresponding evidence for the public sector. This study evaluated the impact of AIDS on the costs and service delivery capacity of a government agency, the Zambia Wildlife Authority (ZAWA).

METHODS

Data were collected on workforce characteristics, mortality, costs, and number of days spent on patrol between 2003 and 2005 by 76 current patrol officers (reference subjects) and 11 patrol officers who died of AIDS or suspected AIDS (index subjects). The impact of AIDS on service delivery capacity and labor costs and the net benefits of providing treatment were estimated.

RESULTS

Reference subjects averaged 197.4 patrol days per year. After adjustment index subjects patrolled 68% less in their last year of service (P < 0.0001), 51% less in their second to last year (P < 0.0001), and 37% less in their third to last year (P < 0.0001). For each employee who died, ZAWA lost an additional 111 person-days for management, funeral attendance, vacancy and staff replacement. Each death also cost ZAWA the equivalent of 3.3 years' annual compensation for care, benefits, recruitment, and training. In 2005, AIDS reduced service delivery capacity by 6.0% and increased labor costs by 9.3%.

CONCLUSION

Impacts on this government agency are substantially larger than observed in the private sector. AIDS is constraining ZAWA's ability to protect Zambia's parks. At a cost of US $500/patient/year, antiretroviral therapy (ART) would result in service improvements and net budgetary savings to ZAWA.

Gender differences in survival in an HIV/AIDS cohort from São Paulo, Brazil

Highly active antiretroviral therapy accounted for significant improvement in AIDS prognosis. However, in areas where access to antiretrovirals is universal, the impact of treatment might have been less remarkable among women. To compare survival between men and women living with HIV, we studied a retrospective cohort of 1072 patients who attended a Brazilian reference center. Time to AIDS-related death was the dependent variable. Medical charts were reviewed to obtain sociodemographic data, clinical, and laboratory outcomes. Cumulative survival probability was estimated by the Kaplan-Meier method and hazard ratios by Cox proportional hazards model. At admission, 55% of men and 38% of women had AIDS. Ninety-one AIDS-related deaths occurred in 6004 person-years of follow-up (PYFU). After adjustment for antiretroviral therapy, predictors of death included: female gender (p = 0.02), age at HIV diagnosis (p = 0.005), lowest CD4 count less than 200 cells/mm(3) (p < 0.001) and highest viral load greater than 100,000 copies per milliliter during follow-up (p = 0.007), having an AIDS-defining illness before admission or during follow-up (p < 0.001). We provide evidence that women have benefited less from care, though admitted to the clinic at earlier stages of HIV disease and offered standardised therapeutic interventions. However, the reasons for such gender differences in survival still remain unclear. Further studies are thus warranted to help recognize factors associated to a higher vulnerability in care among women, what may help establish strategies to enhance care for all people living with HIV and for women, in particular.

Survival from HIV-1 seroconversion in Southern Africa: a retrospective cohort study in nearly 2000 gold-miners over 10 years of follow-up

OBJECTIVE

To obtain robust estimates of survival with HIV in individuals with known dates of seroconversion in Africa in the pre-antiretroviral era.

DESIGN AND METHODS

Mortality rates were estimated in men from four South African gold mines in a retrospective cohort study with 10-year follow-up. HIV testing was carried out with counselling and consent, in random surveys in the early 1990s and in clinics. A total of 1950 HIV-positive men with seroconversion intervals < 3 years were compared with 6164 HIV-negative men with no subsequent evidence of HIV. Unique industry numbers were used to link medical records to demographic and occupational information. Follow-up after leaving the mine was conducted through employment offices across southern Africa, and using South African death registration data.

RESULTS

Follow-up was complete for 85% of those who seroconverted. Median survival was 10.5 years overall: 11.5 years for those aged 15-24 at seroconversion, 10.5 years for those aged 25-34, 9.5 years for those aged 35-44, and 6.3 years for those aged 45+ years. The relative mortality rate in comparison with HIV-uninfected miners increased quickly, reaching 13 for those HIV-infected for at least 9 years, and did not vary by age group. Excess mortality increased with age and duration of infection to > 10% per year. Adjusted to age 25-29 years at seroconversion, 5-year survival was 89% and 10-year 62%.

DISCUSSION

This study reports by far the largest cohort of individuals with known dates of seroconversion available in Africa. After adjusting for age, the survival pattern was similar to that seen in the West before antiretroviral therapy was available.

The emergence of HIV transmitted resistance in Botswana: "when will the WHO detection threshold be exceeded?"

Background

The Botswana antiretroviral program began in 2002 and currently treats 42,000 patients, with a goal of treating 85,000 by 2009. The World Health Organization (WHO) has begun to implement a surveillance system for detecting transmitted resistance that exceeds a threshold of 5%. However, the WHO has not determined when this threshold will be reached. Here we model the Botswana government's treatment plan and predict, to 2009, the likely stochastic evolution of transmitted resistance.

Methods

We developed a model of the stochastic evolution of drug-resistant strains and formulated a birth-death Master equation. We analyzed this equation to obtain an analytical solution of the probabilistic evolutionary trajectory for transmitted resistance, and used treatment and demographic data from Botswana. We determined the temporal dynamics of transmitted resistance as a function of: (i) the transmissibility (i.e., fitness) of the drug-resistant strains that may evolve and (ii) the rate of acquired resistance.

Results

Transmitted resistance in Botswana will be unlikely to exceed the WHO's threshold by 2009 even if the rate of acquired resistance is high and the strains that evolve are half as fit as the wild-type strains. However, we also found that transmission of drug-resistant strains in Botswana could increase to ∼15% by 2009 if the drug-resistant strains that evolve are as fit as the wild-type strains.

Conclusions

Transmitted resistance will only be detected by the WHO (by 2009) if the strains that evolve are extremely fit and acquired resistance is high. Initially after a treatment program is begun a threshold lower than 5% should be used; and we advise that predictions should be made before setting a threshold. Our results indicate that it may be several years before the WHO's surveillance system is likely to detect transmitted resistance in other resource-poor countries that have significantly less ambitious treatment programs than Botswana.

Prevalence of Parental Death Among Young People in South Africa and Risk for HIV Infection

OBJECTIVES

This study estimated the prevalence and sociodemographic characteristics of young people in South Africa who have experienced parental death and examined associations between parental death and young people's HIV status and sexual behaviors.

DESIGN AND METHODS

Data were from a cross-sectional nationally representative household survey of 11,904 15- to 24-year-old South Africans. Surveys included items on sexual behavior and family composition, and oral fluid samples were collected to test for HIV status.

RESULTS

The prevalence of parental death was 27.3% overall: 22.4% reported a father deceased, 7.9% reported a mother deceased, and 3.0% reported both parents deceased. Parental death was disproportionately associated with black ethnicity, impoverished household living conditions, lack of an adult guardian in the home, and not completing compulsory education levels. Controlling for sociodemographic factors, parental death among female participants was significantly associated with HIV-positive status (odds ratio [OR] = 1.25, 95% confidence interval [CI]: 1.08 to 1.44), ever having had oral sex (OR = 1.23, 95% CI: 1.02 to 1.49), ever having had vaginal sex (OR = 1.38, 95% CI: 1.19 to 1.60), and having more than 1 sex partner during the past year (OR = 1.33, 95% CI: 1.07 to 1.64). Among male participants, parental death was significantly associated with ever having had vaginal sex (OR = 1.19, 95% CI: 1.04 to 1.36) and having unprotected sex at the last sexual episode (OR = 1.23, 95% CI: 1.07 to 1.42).

CONCLUSIONS

More than one quarter of young South Africans have experienced parental death. Death of a parent is associated with young female South Africans' HIV status and sexual behaviors among young female and male South Africans. HIV prevention interventions are necessary to address the specific needs of young South Africans who have experienced parental death.

Mortality and morbidity among postpartum HIV-positive and HIV-negative women in Zimbabwe: risk factors, causes, and impact of single-dose postpartum vitamin A supplementation

BACKGROUND

Vitamin A deficiency is common among women in resource-poor countries and is associated with greater mortality during HIV.

METHODS

Fourteen thousand one hundred ten mothers were tested for HIV and randomly administered 400,000 IU vitamin A or placebo at less than 96 hours postpartum. The effects of vitamin A and HIV status on mortality, health care utilization, and serum retinol were evaluated.

RESULTS

Four thousand four hundred ninety-five (31.9%) mothers tested HIV positive. Mortality at 24 months was 2.3 per 1000 person-years and 38.3 per 1000 person-years in HIV-negative and HIV-positive women, respectively. Vitamin A had no effect on mortality. Tuberculosis was the most common cause of death, and nearly all tuberculosis-associated deaths were among HIV-positive women. Among HIV-positive women, vitamin A had no effect on rates of hospitalization or overall sick clinic visits, but did reduce clinic visits for malaria, cracked and bleeding nipples, pelvic inflammatory disease, and vaginal infection. Among HIV-negative women, serum retinol was responsive to vitamin A, but low serum retinol was rare. Among HIV-positive women, serum retinol was largely unresponsive to vitamin A, and regardless of treatment group, the entire serum retinol distribution was shifted 25% less than that of HIV-negative women 6 weeks after dosing.

CONCLUSIONS

Single-dose postpartum vitamin A supplementation had no effect on maternal mortality, perhaps because vitamin A status was adequate in HIV-negative women and apparently unresponsive to supplementation in HIV-positive women.

Creating and validating an algorithm to measure AIDS mortality in the adult population using verbal autopsy

BACKGROUND

Vital registration and cause of death reporting is incomplete in the countries in which the HIV epidemic is most severe. A reliable tool that is independent of HIV status is needed for measuring the frequency of AIDS deaths and ultimately the impact of antiretroviral therapy on mortality.

METHODS AND FINDINGS

A verbal autopsy questionnaire was administered to caregivers of 381 adults of known HIV status who died between 1998 and 2003 in Manicaland, eastern Zimbabwe. Individuals who were HIV positive and did not die in an accident or during childbirth (74%; n = 282) were considered to have died of AIDS in the gold standard. Verbal autopsies were randomly allocated to a training dataset (n = 279) to generate classification criteria or a test dataset (n = 102) to verify criteria. A rule-based algorithm created to minimise false positives had a specificity of 66% and a sensitivity of 76%. Eight predictors (weight loss, wasting, jaundice, herpes zoster, presence of abscesses or sores, oral candidiasis, acute respiratory tract infections, and vaginal tumours) were included in the algorithm. In the test dataset of verbal autopsies, 69% of deaths were correctly classified as AIDS/non-AIDS, and it was not necessary to invoke a differential diagnosis of tuberculosis. Presence of any one of these criteria gave a post-test probability of AIDS death of 0.84.

CONCLUSIONS

Analysis of verbal autopsy data in this rural Zimbabwean population revealed a distinct pattern of signs and symptoms associated with AIDS mortality. Using these signs and symptoms, demographic surveillance data on AIDS deaths may allow for the estimation of AIDS mortality and even HIV prevalence.

Measuring trends in prevalence and incidence of HIV infection in countries with generalised epidemics

OBJECTIVE

Review of recent data and practice to derive guidance on questions relating to the measurement and analysis of trends in HIV prevalence and incidence.

RESULTS

HIV prevalence among pregnant women attending antenatal clinics (ANCs) remains the principal data source to inform trends in the epidemic. Other data sources are: less available, representative of a small section of the population (sex workers, occupational groups), subject to additional bias (for example, voluntary counselling and testing service statistics), or are not yet available for multiple years (national surveys). Validity of HIV prevalence results may change over time due to improvements in HIV tests per se and implementation of laboratory quality assurance systems. The newer laboratory tests for recent infections require further validation and development of methodology to derive estimates of HIV incidence.

CONCLUSIONS

Issues to consider during statistical analyses of trends among ANC attendees are: inclusion of consistent sites only, use of confidence intervals, stratification by site when performing a statistical test for trend, the need for at least three observations in a surveillance system with data collection every one to two years, and sound judgement. Trends in HIV prevalence among pregnant 15-24 year olds attending ANCs can be used to approximate trends in incidence. Indepth small area research studies are useful to inform the interpretation of surveillance data and provide directly measured trends in prevalence and incidence. Modelling can assess changes over time in prevalence, incidence, and mortality at the same time. Modelling tools need to be further developed to allow incorporation of estimates of HIV incidence and mortality, as these data are likely to become available in the future. To increase their explanatory power, models should also be extended to incorporate programmatic inputs.

Estimates of eligibility for antiretroviral treatment (ART) and projected ART impact on AIDS mortality among South African educators

The study assessed the proportion of HIV-infected educators that need antiretroviral treatment (ART) according to current criteria, and estimated the impact of ART on AIDS mortality by modelling scenarios with and without access to ART. Specimens for HIV testing were obtained from 17 088 educators and a sub-sample of 444 venous blood specimens from HIV-positive educators was selected for a CD4 cell count analysis. The Spectrum model package was used for estimating AIDS-associated mortality and projecting the impact of ART scenarios. The results of the CD4 cell count analysis in the HIV-positive educator study population showed that 8% had fewer than 100, 22% fewer than 200, 52% fewer than 350, and 72% fewer than 500 CD4 cells/mm3. Based on the proportion of HIV-positive educators with a CD4 cell count < 200 cells/mm3 we estimated that in 2005 approximately 10 700 educators would need ART according to current SA government guidelines. For the baseline scenario without ART the number of AIDS deaths among HIV-infected educators was projected to increase from 1 992 deaths in 2000 to 5 260 in 2010. The number of projected AIDS deaths in the educator study population was estimated to be 4 414 in 2005, with almost 50% of the AIDS deaths occurring in the 35 - 44 age group. The estimates suggest that in 2005 9.1% of the HIV-infected educators, or 1.2% of the total educator population, will be dying of AIDS. By 2010, a reduction of almost 50% in AIDS deaths was estimated for the treatment scenario with 90% ART coverage, compared with the baseline scenario without treatment. The ART impact scenarios illustrate that a relatively high ART coverage would be needed to ensure a substantial impact of ART on HIV/AIDS-associated mortality.

Impact of AIDS on adult mortality: a morgue-based study in Pointe-Noire, Republic of Congo

OBJECTIVE

To measure the impact of AIDS on adult mortality by systematically investigating all deaths during 3 months, in the city of Pointe-Noire where the HIV epidemic emerged 20 years ago and levelled-off around 5% among adults.

DESIGN

: Exhaustive morgue-based study, in a city where by law all bodies should be registered at the morgue before they can be legally buried.

METHODS

From 30 June to 19 October 2001, a clinical examination of all bodies registered at the morgue was performed by a physician, and blood samples were systematically drawn for HIV testing. Relatives were interviewed on circumstances of death. Additional information was gathered from hospital files for cases previously hospitalized. Age- and sex-specific mortality rates were calculated using the population at risk derived from the 2001 census.

RESULTS

Overall, 1309 adult deaths were investigated and 96.5% of the bodies registered at the morgue were tested for HIV. Forty-five percent of the deaths (570) were due to AIDS. The HIV prevalence was higher in female than in male deaths (57.1 versus 44.8%; P < 0.001). The AIDS-mortality rate among adults was 6.3 per thousand for women and 4.9 per thousand for men. Among 1000 young adults aged 15 years, 442 girls and 482 boys will not reach age 60 years (45q15). Without AIDS these would have been 216 and 307, respectively.

CONCLUSIONS

Our study provides a direct measure of the impact of AIDS on mortality relative to other causes. In the most productive age group, 25-44 years, mortality is tripled by AIDS.

Impact of the HIV epidemic on population and household structure: the dynamics and evidence to date

BACKGROUND

HIV is contracted most frequently at birth and during early adulthood. The epidemic may thus impact the demographic structure and the household structure of affected populations.

METHODS

This paper reviews earlier evidence of such an impact, uses demographic theory to anticipate its changes over time, and reviews the most recent evidence for indications of these changes.

RESULTS

Modest increases in the male : female ratio are beginning to show within certain age groups only (approximately 15% among 25-34 year olds). Similarly sized increases in the proportion of 15-29 year olds relative to 30-54 year olds are observed in some age pyramids. These 'youth bulges' are expected to fade out, whereas an aging effect phases in with the fertility impact of the epidemic. In the longer run, the size of all age groups will be reduced, but relatively less so for middle-aged adults. Proportions of orphans and widows have increased in the most affected countries. Fewer remarriage probabilities for widows were observed. Resulting increases in the proportion of female-headed households should only be temporary, as female mortality is catching up with male mortality. The number of double orphans is beginning to increase, but overall, orphans continue to live predominantly with a family member, most often the grandparents if not with the surviving parent.

CONCLUSION

To date, the epidemic's impact on the population and household structure has been limited by demographic (aging) and social (adaptive movements of kin across households) processes that contribute to diffuse the epidemic throughout the entire population and all households.