Association between breastfeeding duration and educational attainment in rural Southwest Uganda: a population-based cohort study

BACKGROUND

Breastfeeding is important for early childhood nutrition and health. The positive effects on educational outcomes may be attributed to socioeconomic factors. Socioeconomic status is not a strong predictor of breastfeeding in sub-Saharan African countries. Yet, few studies have investigated the association between breastfeeding and educational outcomes in these countries.

OBJECTIVE

This study investigated the association between breastfeeding duration and children's educational attainment in rural Southwest Uganda.

METHODS

We analysed longitudinal data on 3018 children who had information on breastfeeding and were followed for at least 5 years, with at least one primary school grade recorded by 2005. Data on breastfeeding duration were collected from mothers. The highest school grade was recorded repeatedly between ages 6 and 12 years. We calculated age-for-grade based on whether a child was on, over, or under the official age for a grade. Generalised estimating equations and binary logistic regression estimated the effect of breastfeeding duration on being 2 years, 3 or more years, or any years over-age for grade in primary school, adjusting for socioeconomic status and maternal-child characteristics.

RESULTS

Most mothers breastfed for more than a year. Just over one-third breastfed for 18-23 months, and 30% breastfed for longer. By age eight, 42% of the children were two years over-age for their grade. Three or more years over-age for grade increased from 19% at age nine to 56% at age 12. Both adjusted and unadjusted estimates were consistent in showing reduced odds for children being 2 years, 3 or more years, or any years over-age for grade among children breastfed for 7-12, 13-17, 18-23, and > 23 months compared to those breastfed for 0-6 months. There was no evidence to support an overall association between breastfeeding duration and being over-age for grade. There was no evidence of association in the sex and age sub-group analyses.

CONCLUSION

Although we found no association between breastfeeding duration and educational attainment, breastfeeding remains important for children's health and nutrition, and mothers should be encouraged and supported to breastfeed for the recommended duration.

Rates of sexual partner acquisition from nationally representative surveys: variation between countries and by age, sex, wealth, partner and HIV status

BACKGROUND

Knowing levels and determinants of partnership acquisition will help inform interventions that try to reduce transmission of sexually transmitted infections (STIs) including HIV.

METHODS

We used population-based, cross-sectional data from 47 Demographic and Health Surveys to calculate rates of partner acquisition among men and women (15-49years), and identified socio-demographic correlates for partner acquisition. Partner acquisition rates were estimated as the total number of acquisitions divided by the person-time in the period covered by the survey. For each survey and by sex, we estimated age-specific partner acquisition rates and used age-adjusted piecewise exponential survival models to explore whether there was any association between wealth, HIV status and partner status with partner acquisition rates.

RESULTS

Across countries, the median partner acquisition rates were 30/100 person-years for men (interquartile range 21-45) and 13/100 person-years for women (interquartile range 6-18). There were substantial variations in partner acquisition rates by age. Associations between wealth and partner acquisition rates varied across countries. People with a cohabiting partner were less likely to acquire a new one, and this effect was stronger for women than men and varied substantially between countries. Women living with HIV had higher partner acquisition rates than HIV-negative women but this association was less apparent for men. At a population level, partner acquisition rates were correlated with HIV incidence.

CONCLUSIONS

Partner acquisition rates are variable and are associated with important correlates of STIs and thus could be used to identify groups at high risk of STIs.

Comparison of survival analysis approaches to modelling age at first sex among youth in Kisesa Tanzania

BACKGROUND

Many studies analyze sexual and reproductive event data using descriptive life tables. Survival analysis has better power to estimate factors associated with age at first sex (AFS), but proportional hazards models may not be right model to use. This study used accelerated failure time (AFT) models, restricted Mean Survival time model (RMST) models, with semi and non-parametric methods to assess age at first sex (AFS), factors associated with AFS, and verify underlying assumptions for each analysis.

METHODS

Self-reported sexual debut data was used from respondents 15-24 years in eight cross-sectional surveys between 1994-2016, and from adolescents' survey in an observational community study (2019-2020) in northwest Tanzania. Median AFS was estimated in each survey using non-parametric and parametric models. Cox regression, AFT parametric models (exponential, gamma, generalized gamma, Gompertz, Weibull, log-normal and log-logistic), and RMST were used to estimate and identify factors associated with AFS. The models were compared using Akaike information criterion (AIC) and Bayesian information criterion (BIC), where lower values represent a better model fit.

RESULTS

The results showed that in every survey, the Cox regression model had higher AIC and BIC compared to the other models. Overall, AFT had the best fit in every survey round. The estimated median AFS using the parametric and non-parametric methods were close. In the adolescent survey, log-logistic AFT showed that females and those attending secondary and higher education level had a longer time to first sex (Time ratio (TR) = 1.03; 95% CI: 1.01-1.06, TR = 1.05; 95% CI: 1.02-1.08, respectively) compared to males and those who reported not being in school. Cell phone ownership (TR = 0.94, 95% CI: 0.91-0.96), alcohol consumption (TR = 0.88; 95% CI: 0.84-0.93), and employed adolescents (TR = 0.95, 95% CI: 0.92-0.98) shortened time to first sex.

CONCLUSION

The AFT model is better than Cox PH model in estimating AFS among the young population.

Effects of exclusive breastfeeding on educational attainment and longitudinal trajectories of grade progression among children in a 13-year follow-up study in Malawi

The benefits of exclusive breastfeeding (EBF) for infant health and survival are well documented. However, its impact on educational outcomes has been contested and poorly researched in Africa. It has been hypothesised that positive associations reported in high-income countries can be attributed to residual confounding by socioeconomic status (SES). Our study investigated whether EBF duration in infancy is associated with educational attainment and age-for-grade attainment trajectories at school-age in rural Malawi. Longitudinal data on 1021 children at the Karonga demographic surveillance site in Malawi were analysed. Breastfeeding data were collected 3 months after birth and again at age one. The school grade of each child was recorded each year from age 6 until age 13. We calculated age-for-grade based on whether a child was at, over, or under the official expected age for a grade. Generalised estimating equations estimated the average effect of breastfeeding on age-for-grade. Latent class growth analysis identified age-for-grade trajectories, and multinomial logistic regression examined their associations with EBF. Maternal-child characteristics, SES, and HIV status were controlled. Overall, 35.9% of the children were exclusively breastfed for 6 months. Over-age for grade steadily increased from 9.6% at age 8 to 41.9% at age 13. There was some evidence that EBF for 6 months was associated with lower odds of being over-age for grade than EBF for less than 3 months (aOR = 0.82, 95%CI = 0.64-1.06). In subgroup analyses, children exclusively breastfed for 6 months in infancy were less likely to be over-age for grades between ages 6-9 (aOR = 0.64, 95%CI = 0.43-0.94). Latent class growth analysis also provided some evidence that EBF reduced the odds of falling behind in the early school grades (aOR = 0.66, 95%CI = 0.41-1.08) but not later. Our study adds to the growing evidence that EBF for 6 months has benefits beyond infant health and survival, supporting the WHO's recommendation on EBF.

Comparison of programmatic data from antenatal clinics with population-based HIV prevalence estimates in the era of universal test and treat in western Kenya

OBJECTIVE

To compare HIV prevalence estimates from routine programme data in antenatal care (ANC) clinics in western Kenya with HIV prevalence estimates in a general population sample in the era of universal test and treat (UTT).

METHODS

The study was conducted in the area covered by the Siaya Health Demographic Surveillance System (Siaya HDSS) in western Kenya and used data from ANC clinics and the general population. ANC data (n = 1,724) were collected in 2018 from 13 clinics located within the HDSS. The general population was a random sample of women of reproductive age (15-49) who reside in the Siaya HDSS and participated in an HIV sero-prevalence survey in 2018 (n = 2,019). Total and age-specific HIV prevalence estimates were produced from both datasets and demographic decomposition methods were used to quantify the contribution of the differences in age distributions and age-specific HIV prevalence to the total HIV prevalence estimates.

RESULTS

Total HIV prevalence was 18.0% (95% CI 16.3-19.9%) in the ANC population compared with 18.4% (95% CI 16.8-20.2%) in the general population sample. At most ages, HIV prevalence was higher in the ANC population than in the general population. The age distribution of the ANC population was younger than that of the general population, and because HIV prevalence increases with age, this reduced the total HIV prevalence among ANC attendees relative to prevalence standardised to the general population age distribution.

CONCLUSION

In the era of UTT, total HIV prevalence among ANC attendees and the general population were comparable, but age-specific HIV prevalence was higher in the ANC population in most age groups. The expansion of treatment may have led to changes in both the fertility of women living with HIV and their use of ANC services, and our results lend support to the assertion that the relationship between ANC and general population HIV prevalence estimates are highly dynamic.

No association between fertility desire and HIV infections among men and women: Findings from community-based studies before and after implementation of an early antiretroviral therapy (ART) initiation program in the rural district of North-western Tanzania

Background: Fertility is associated with the desire to have children. The impacts of HIV and antiretroviral therapy (ART) on fertility are well known, but their impacts on the desire for children are less well known in Tanzania. We used data from two studies carried out at different periods of ART coverage in rural Tanzania to explore the relationship between HIV infection and fertility desires in men and women. Methods: We conducted secondary data analysis of the two community-based studies conducted in 2012 and 2017 in the Magu Health and Demographic system site, in Tanzania. Information on fertility desires, HIV status, and social-economic and demographic variables were analyzed. Fertility desire was defined as whether or not the participant wanted to bear a child in the next two years. The main analysis used log-binomial regression to assess the association between fertility desire and HIV infection. Results: In the 2012 study, 43% (95% CI 40.7-45.3) of men and 33.3% (95% CI 31.8 - 35.0) women wanted another child in the next two years. In 2017 the percentage rose to 55.7% (95% CI 53.6 - 57.8) in men and 41.5% (95% CI 39.8 - 43.1) in women. Although fertility desire in men and women were higher in HIV uninfected compared to HIV infected, age-adjusted analysis did not show a statistical significance difference in both studies (2012: PR=1.02, 95%CI 0.835 - 1.174, p<0.915 and 2017: PR = 0.90 95%CI 0.743 - 1.084 p= 0.262). Discussion: One-third of women and forty percent of men desired for fertility in 2012, while forty percent of women and nearly half of men desired for fertility in 2017. The data showed fertility desire, in 2012 and 2017 were not related to HIV infection in both periods of ART coverage.

The association of breastfeeding with cognitive development and educational achievement in sub-Saharan Africa: A systematic review

Background

Systematic reviews and meta-analyses of studies mainly from high-income countries suggest that breastfeeding improves cognitive function and educational achievement. However, these associations may be a manifestation of who breastfeeds in these settings rather than an actual effect of breastfeeding. We investigated the association of breastfeeding with cognitive development and educational achievements in sub-Saharan Africa, where breastfeeding is the norm, and socioeconomic status is not strongly correlated with ever breastfeeding.

Methods

We searched Medline, Embase, PsycINFO, Cochrane Central Register of Controlled Trials (CENTRAL), and Africa-Wide Information in January 2021 for studies that assessed the cognitive and educational benefits of breastfeeding in children and adolescents in sub-Saharan Africa. Two reviewers independently screened, extracted, and critically appraised the included studies.

Results

After reviewing 5552 abstracts and 151 full-text articles, seventeen studies on cognitive development and two on educational achievements met our predefined inclusion criteria. The included studies were from ten sub-Saharan African countries and published between 2013 and 2021, with sample sizes ranging from 54 to 6573. Most of the studies (n = 14) were prospective cohort studies, but only nine collected data on breastfeeding prospectively. The studies differed in analytic approaches and cognitive and educational achievements measurements. Of the 17 studies on cognitive development, only four adjusted sufficiently for key confounders. None of these four studies found an overall association between breastfeeding and cognitive development in children or adolescents in sub-Saharan Africa. The two studies on education measured achievements based on the highest grade of school attained, 12 or more years of education, or grade repetition at age 7-11 years. Both studies adjusted for a range of sociodemographic factors and found no evidence that children exclusively breastfed or breastfed for a longer duration have a better educational outcome than sub-optimally breastfed children.

Conclusions

The current evidence from sub-Saharan Africa is limited but does not corroborate previous findings that breastfeeding is associated with improved cognitive development and educational achievement.

Registration

This study is registered with PROSPERO, CRD42021236009.

Time trends in the prevalence and determinants of age-appropriate breast feeding among children aged 0-23 months in Ghana: a pooled analysis of population-based surveys, 2003-2017

OBJECTIVE

We assessed the sociodemographic and maternal-child characteristics associated with age-appropriate breast feeding among children aged 0-23 months in Ghana.

METHODS

We pooled data on 12 743 children aged 0-23 months from three Demographic and Health Surveys (2003, 2008 and 2014) and three Multiple Indicator Cluster Surveys (2006, 2011 and 2017-2018). The outcome was age-appropriate breast feeding from birth to 23 months, with age-appropriate breast feeding defined as exclusive breast feeding at 0-5 months (ie, at less than 6 months) and breastfeeding alongside appropriate complementary feeding at 6-23 months. Potential determinants were maternal-child sociodemographic, obstetric and healthcare factors. Logistic regression was used to determine the factors associated with age-appropriate breast feeding. We accounted for the complex sampling design of the cross-sectional surveys in the analysis.

RESULTS

Most children aged 0-3 months were exclusively breastfed. Among children aged 4-5 months, the most common feeding pattern was breastfeeding alongside water and/or solid foods. Exclusive breastfeeding prevalence in children less than 6 months peaked in 2008 at 62.8% and declined to 42.9% in 2017. For 6-11 month olds, the percentage experiencing age-appropriate breast feeding has been stable over the last four surveys, ranging from 79.3% in 2008 to 81.1% in 2017. Age-appropriate breast feeding in 12-23 month olds declined from 77.8% in 2003 to 61.2% in 2017. Rural residence, younger age, non-facility births and multiple births were associated with decreased odds of exclusively breast feeding. For 6-11 month olds, age-appropriate breast feeding was less likely if the woman did not receive postnatal care. Younger age, being unmarried, high income, wanting a child later and earlier birth order were associated with decreased odds of age-appropriate breast feeding in 12-23 month olds.

CONCLUSION

Ghanaian children are now less likely to be exclusively breastfed than they were a decade ago. To succeed, breastfeeding promotion programmes should adopt approaches that address the predictors of suboptimal breast feeding at each age, as identified in this study.

The prevalence and incidence of HIV in the ART era (2006-2016) in North West Tanzania

Background

Sub-Saharan countries bears a disproportionate percentage of HIV infections and HIV related deaths despite the efforts to strengthen HIV prevention and treatments services, including ART. It is important to demonstrate how these services have contributed to reducing the epidemic using available population data.

Methods

We estimated the prevalence and incidence rates from a cohort running over 23 years in Magu District, Mwanza Region-North West Tanzania. Adults 15 years and over who were residents of the Kisesa observational HIV cohort study between 2006 and 2016 were eligible for inclusion. Survival analysis was used to calculate person-time at risk, incidence rates and 95% confidence intervals (CI). Cox regression models were used for the risk factor analyses disaggregated by sex and age group.

Results

The HIV prevalence in the sero-surveys decreased from 7.2% in 2006/07 to 6.6% in 2016, with a notable decrease of over 50% for both men and women aged 15-24 years. The incidence rate for HIV was estimated to be 5.5 (95% CI 4.6 - 6.6) per 1000 person-years in women compared to 4.6 (95% CI 3.5 – 5.8) in men, with a decrease over time. Despite the availability of ART services, the uptake is still small.

Conclusions

New infections are still occurring, with high HIV incidence in individuals aged below 45 years. With new guidelines and the 95-95-95 UNAIDS target, prevalence and incidence must be adequately assessed. In addition, there is a need for additional efforts to assess the impact of HIV/AIDS prevention programmes and intervention services, especially in these areas where resources are limited.

HIV acquisition in pregnancy: implications for mother-to-child transmission at the population level in sub-Saharan Africa

Introduction

A recent sero‐discordant couple study showed an elevated risk of HIV‐acquisition during the pregnancy/postpartum period per‐condomless‐coital‐act. This, along with previous studies, has led to concern over possible increased risk of mother‐to‐child (vertical) transmission, due to the initial high viral load in the first months after seroconversion, in a time when the woman and health services may be unaware of her status. This study looks at whether behavioural differences during the pregnant/postpartum period could reduce the impact of elevated risk of HIV acquisition per‐condomless‐coital‐act at the population level.

Methods

We used data from 60 demographic and health surveys from 32 sub‐Saharan African countries. Using the HIV status of couples, we estimated differences in serodiscordancy between HIV‐negative women who were pregnant/postpartum compared to those who were not pregnant/postpartum. We compare the risk of sexual activity over the pregnant/postpartum period to those not pregnant/postpartum. Using these risks of serodiscordancy and sexual activity along with estimates of increased HIV risk in the pregnancy/postpartum period per‐condomless‐coital‐act, we estimated a population‐level risk of HIV acquisition and acute infection, during pregnancy/postpartum compared to those not pregnant/postpartum.

Results

Sexual activity during pregnancy/postpartum varies considerably. In general, sexual activity is high in the first trimester of pregnancy, then declines to levels lower than among women not pregnant/postpartum, and is at its lowest in the first months postpartum. Adjusted for age and survey, pooled results show HIV‐negative pregnant women are less likely to have an HIV‐positive partner compared to those not pregnant/postpartum (risk ratio (RR) = 0.78, 95% CI = 0.68–0.89) and comparing the postpartum period (RR = 0.85, 95% CI = 0.73–0.99). Estimated population‐level risk for HIV acquisition and acute infection in pregnancy/postpartum was lower than would be inferred directly from per‐condomless‐coital‐act estimates in most countries, over the time of most risk of mother‐to‐child transmission, though there was variation by country and month of pregnancy/postpartum.

Conclusions

Estimates of population‐level HIV acquisition risk in sub‐Saharan Africa should not be taken directly from per‐condomless‐coital‐act studies to estimate vertical transmission. Changes in sexual behaviour and differences in HIV‐serodiscordancy during pregnancy/postpartum reduce the impact of increased risk of HIV acquisition per‐condomless‐coital‐act, this will vary by region.

Age patterns of HIV incidence in eastern and southern Africa: a modelling analysis of observational population-based cohort studies

BACKGROUND

As the HIV epidemic in sub-Saharan Africa matures, evidence about the age distribution of new HIV infections and how this distribution has changed over the epidemic is needed to guide HIV prevention. We aimed to assess trends in age-specific HIV incidence in six population-based cohort studies in eastern and southern Africa, reporting changes in mean age at infection, age distribution of new infections, and birth cohort cumulative incidence.

METHODS

We used a Bayesian model to reconstruct age-specific HIV incidence from repeated observations of individuals' HIV serostatus and survival collected among population HIV cohorts in rural Malawi, South Africa, Tanzania, Uganda, and Zimbabwe, in a collaborative analysis of the ALPHA network. We modelled HIV incidence rates by age, time, and sex using smoothing splines functions. We estimated incidence trends separately by sex and study. We used estimated incidence and prevalence results for 2000-17, standardised to study population distribution, to estimate mean age at infection and proportion of new infections by age. We also estimated cumulative incidence (lifetime risk of infection) by birth cohort.

FINDINGS

Age-specific incidence declined at all ages, although the timing and pattern of decline varied by study. The mean age at infection was higher in men (cohort mean 27·8-34·6 years) than in women (24·8-29·6 years). Between 2000 and 2017, the mean age at infection per cohort increased slightly: 0·5 to 2·8 years among men and -0·2 to 2·5 years among women. Across studies, between 38% and 63% (cohort medians) of the infections in women were among those aged 15-24 years and between 30% and 63% of infections in men were in those aged 20-29 years. Lifetime risk of HIV declined for successive birth cohorts.

INTERPRETATION

HIV incidence declined in all age groups and shifted slightly to older ages. Disproportionate new HIV infections occur among women aged 15-24 years and men aged 20-29 years, supporting focused prevention in these groups. However, 40-60% of infections were outside these ages, emphasising the importance of providing appropriate HIV prevention to adults of all ages.

FUNDING

Bill & Melinda Gates Foundation.

Strengthening measurement and performance of HIV prevention programmes

Indicators for the measurement of programmes for the primary prevention of HIV are less aligned than indicators for HIV treatment, which results in a high burden of data collection, often without a clear vision for its use. As new evidence becomes available, the opportunity arises to critically evaluate the way countries and global bodies monitor HIV prevention programmes by incorporating emerging data on the strength of the evidence linking various factors with HIV acquisition, and by working to streamline indicators across stakeholders to reduce burdens on health-care systems. Programmes are also using new approaches, such as targeting specific sexual networks that might require non-traditional approaches to measurement. Technological advances can support these new directions and provide opportunities to use real-time analytics and new data sources to more effectively understand and adapt HIV prevention programmes to reflect population movement, risks, and an evolving epidemic.

Trends in sexual activity and demand for and use of modern contraceptive methods in 74 countries: a retrospective analysis of nationally representative surveys

BACKGROUND

A quarter of a century ago, two global events-the International Conference on Population and Development in Cairo, and the Fourth World Conference on Women in Beijing-placed gender equality and reproductive health and rights at the centre of the development agenda. Progress towards these goals has been slower than hoped. We used survey data and national-level indicators of social determinants from 74 countries to examine change in satisfaction of contraceptive need from a contextual perspective.

METHODS

We searched for individual-level data from repeated nationally representative surveys that included information on sexual and reproductive health, and created a single dataset by harmonising data from each survey to a standard data specification. We described the relative timings of sexual initiation, first union (cohabitation or marriage), and first birth and used logistic regression to show the change in prevalence of sexual activity, demand for contraception, and modern contraceptive use. We used linear regression to examine country-level associations between the gender development index and the expected length of time in education for women and the three outcomes: sexual activity, demand for contraception, and modern contraceptive use. We used principal component analysis to describe countries using a combination of social-structural and behavioural indicators and assessed how well the components explained country-level variation in the proportion of women using contraception with fractional logistic regression.

FINDINGS

In 34 of the 74 countries examined, proportions of all women who were sexually active, not wanting to conceive, and not using a modern contraceptive method decreased over time. Proportions of women who had been sexually active in the past year changed over time in 43 countries, with increases in 30 countries; demand for contraception increased in 42 countries, and use of a modern method of contraception increased in 37 countries. Increases over time in met need for contraception were correlated with increases in gender equality and with women's time in education. Regression analysis on the principal components showed that country-level variation in met contraceptive need was largely explained by a single component that combined behavioural and social-contextual variables.

INTERPRETATION

Progress towards satisfying demand for contraception should take account of the changing context in which it is practised. To remove the remaining barriers, policy responses-and therefore research priorities-could require a stronger focus on social-structural determinants and broader aspects of sexual health.

FUNDING

UNDP/UNFPA/UNICEF/WHO/World Bank Special Programme of Research, Development and Research Training in Human Reproduction.

Population-level adult mortality following the expansion of antiretroviral therapy in Rakai, Uganda

There are limited data on the impact of antiretroviral therapy (ART) on population-level adult mortality in sub-Saharan Africa. We analysed data for 2000-14 from the Rakai Community Cohort Study (RCCS) in Uganda, where free ART was scaled up after 2004. Using non-parametric and parametric (Weibull) survival analysis, we estimated trends in average person-years lived between exact ages 15 and 50, per capita life-years lost to HIV, and the mortality hazards of people living with HIV (PLHIV). Between 2000 and 2014, average adult life-years lived before age 50 increased significantly, from 26.4 to 33.5 years for all women and from 28.6 to 33.8 years for all men. As of 2014, life-years lost to HIV had declined significantly, to 1.3 years among women and 0.4 years among men. Following the roll-out of ART, mortality reductions among PLHIV were initially larger in women than men, but this is no longer the case.

Relative patterns of sexual activity and fertility among HIV positive and negative women-Evidence from 46 DHS

Objectives

Projections of fertility of HIV positive women as ART scales up are needed to plan prevention of mother-to-child transmission (PMTCT) services. We describe differences in exposure to pregnancy between HIV positive and HIV negative women by age, region and national ART coverage to evaluate the extent to which behavioural differences explain lower fertility among HIV positive women and assess whether exposure to pregnancy has changed with antiretroviral treatment (ART) scale-up.

Methods

We analysed 46 nationally representative household surveys in sub-Saharan Africa conducted between 2003 and 2015 to estimate risk of exposure to recent sex and pregnancy of HIV positive and HIV negative women by age using a log binomial model. We tested for regional and urban/rural differences and associations with national ART coverage. We estimated an adjusted fertility rate ratio of HIV positive to HIV negative women adjusting for differences in exposure to pregnancy.

Results

Exposure to pregnancy differs significantly between HIV positive and negative women by age, modified by region. Younger HIV positive women have a higher exposure to pregnancy than HIV negative women and the opposite is true at older ages. The switch occurs at 25–29 for rural women and 30–34 for urban women. There was no evidence that exposure to pregnancy of HIV positive women have changed as national ART coverage increased. The inferred rate of fecundity of HIV positive women when adjusted for differences in exposure to pregnancy were lower than unadjusted fertility rate ratios in women aged 20–29 and 20–24 in urban and rural areas respectively varying between 0.6 and 0.9 over regions.

Discussion

The direct effects of HIV on fertility are broadly similar across ages, while the dramatic age gradient that has frequently been observed is largely attributable to variation in relative sexual exposure by age.

The Network for Analysing Longitudinal Population-based HIV/AIDS data on Africa (ALPHA): Data on mortality, by HIV status and stage on the HIV care continuum, among the general population in seven longitudinal studies between 1989 and 2014

Timely progression of people living with HIV (PLHIV) from the point of infection through the pathway from diagnosis to treatment is important in ensuring effective care and treatment of HIV and preventing HIV-related deaths and onwards transmission of infection.  Reliable, population-based estimates of new infections are difficult to obtain for the generalised epidemics in sub-Saharan Africa.  Mortality data indicate disease burden and, if disaggregated along the continuum from diagnosis to treatment, can also reflect the coverage and quality of different HIV services.  Neither routine statistics nor observational clinical studies can estimate mortality prior to linkage to care nor following disengagement from care.  For this, population-based data are required. The Network for Analysing Longitudinal Population-based HIV/AIDS data on Africa brings together studies in Kenya, Malawi, South Africa, Tanzania, Uganda, and Zimbabwe.  Eight studies have the necessary data to estimate mortality by HIV status, and seven can estimate mortality at different stages of the HIV care continuum.  This data note describes a harmonised dataset containing anonymised individual-level information on survival by HIV status for adults aged 15 and above. Among PLHIV, the dataset provides information on survival during different periods: prior to diagnosis of infection; following diagnosis but before linkage to care; in pre-antiretroviral treatment (ART) care; in the first six months after ART initiation; among people continuously on ART for 6+ months; and among people who have ever interrupted ART.

The relationship between HIV and fertility in the era of antiretroviral therapy in sub-Saharan Africa: evidence from 49 Demographic and Health Surveys

Objectives

To describe regional differences in the relative fertility of HIV‐positive vs. HIV‐negative women and changes as antiretroviral treatment (ART) is scaled up, to improve estimates of predicted need for and coverage of prevention of mother‐to‐child transmission services at national and subnational levels.

Methods

We analysed 49 nationally representative household surveys in sub‐Saharan Africa between 2003 and 2016 to estimate fertility rate ratios of HIV‐positive and HIV‐negative women by age using exponential regression and test for regional and urban/rural differences. We estimated the association between national ART coverage and the relationship between HIV and fertility.

Results

Significant regional differences exist in HIV and fertility relationships, with less HIV‐associated subfertility in Southern Africa. Age patterns of relative fertility are similar. HIV impact on fertility is weaker in urban than rural areas. For women below age 30, regional and urban/rural differences are largely explained by differences in age at sexual debut. Higher levels of national ART coverage were associated with slight attenuation of the relationship between HIV and fertility.

Conclusions

Regional differences in HIV‐associated subfertility and urban–rural differences in age patterns of relative fertility should be accounted for when predicting need for and coverage of PMTCT services at national and subnational level. Although HIV impacts on fertility are somewhat reduced at higher levels of national ART coverage, differences in fertility between HIV positive and negative remain, and fertility of women on ART should not be assumed to be the same as HIV‐negative women. There were few data in recent years, when ART has reached high levels, and this relationship should continue to be assessed as further evidence becomes available.

Measuring the Impact of Antiretroviral Therapy Roll-Out on Population Level Fertility in Three African Countries

Background

UNAIDS official estimates of national HIV prevalence are based on trends observed in antenatal clinic surveillance, after adjustment for the reduced fertility of HIV positive women. Uptake of ART may impact on the fertility of HIV positive women, implying a need to re-estimate the adjustment factors used in these calculations. We analyse the effect of antiretroviral therapy (ART) provision on population-level fertility in Southern and East Africa, comparing trends in HIV infected women against the secular trends observed in uninfected women.

Methods

We used fertility data from four community-based demographic and HIV surveillance sites: Kisesa (Tanzania), Masaka and Rakai (Uganda) and uMkhanyakude (South Africa). All births to women aged 15–44 years old were included in the analysis, classified by mother’s age and HIV status at time of birth, and ART availability in the community. Calendar time period of data availability relative to ART Introduction varied across the sites, from 5 years prior to ART roll-out, to 9 years after. Calendar time was classified according to ART availability, grouped into pre ART, ART introduction (available in at least one health facility serving study site) and ART available (available in all designated health facilities serving study site). We used Poisson regression to calculate age adjusted fertility rate ratios over time by HIV status, and investigated the interaction between ART period and HIV status to ascertain whether trends over time were different for HIV positive and negative women.

Results

Age-adjusted fertility rates declined significantly over time for HIV negative women in all four studies. However HIV positives either had no change in fertility (Masaka, Rakai) or experienced a significant increase over the same period (Kisesa, uMkhanyakude). HIV positive fertility was significantly lower than negative in both the pre ART period (age adjusted fertility rate ratio (FRR) range 0.51 95%CI 0.42–0.61 to 0.73 95%CI 0.64–0.83) and when ART was widely available (FRR range 0.57 95%CI 0.52–0.62 to 0.83 95%CI 0.78–0.87), but the difference has narrowed. The interaction terms describing the difference in trends between HIV positives and negatives are generally significant.

Conclusions

Differences in fertility between HIV positive and HIV negative women are narrowing over time as ART becomes more widely available in these communities. Routine adjustment of ANC data for estimating national HIV prevalence will need to allow for the impact of treatment.

Uptake of services for prevention of mother-to-child transmission of HIV in a community cohort in rural Tanzania from 2005 to 2012

Background

Estimates of population-level coverage with prevention of mother-to-child transmission (PMTCT) services are vital for monitoring programmes but are rarely undertaken. This study describes uptake of PMTCT services among HIV-positive pregnant women in a community cohort in rural Tanzania.

Methods

Kisesa cohort incorporates demographic and HIV sero-surveillance rounds since 1994. Cohort data were linked retrospectively to records from four Kisesa clinics with PMTCT services from 2009 (HIV care and treatment clinic (CTC) available in one facility from 2008; referrals to city hospitals for PMTCT and antiretroviral treatment (ART) from 2005). The proportion of HIV-positive pregnant women residing in Kisesa in 2005–2012 who accessed PMTCT service components (based on linkage to facility records) was calculated per HIV-positive pregnancy and by year, with adjustments made to account for the sensitivity of the linkage algorithm.

Results

Out of 1497 HIV-positive pregnancies overall (to 849 women), 26 % (n = 387/1497) were not linked to any facility records, 35 % (n = 519/1497) registered for ANC but not HIV services (29 % (n = 434/1497) were not tested at ANC or diagnosed previously), 8 % (n = 119/1497) enrolled in PMTCT but not CTC services (6 % (n = 95/1497) received antiretroviral prophylaxis), and 32 % (n = 472/1497) registered for CTC (14 % (n = 204/1497) received ART or prophylaxis) (raw estimates). Adjusted estimates for coverage with ANC were 92 %, 57 % with HIV care, and 29 % with antiretroviral drugs in 2005–2012, trending upwards over time.

Conclusions

Population-level coverage with PMTCT services was low overall, with weaknesses throughout the service continuum, but increased over time. Option B+ should improve coverage with antiretrovirals for PMTCT through simplified decisions for initiating ART, but will rely on strengthening access to CTC services.

Electronic supplementary material

The online version of this article (doi:10.1186/s12913-015-1249-6) contains supplementary material, which is available to authorized users.

How have ART treatment programmes changed the patterns of excess mortality in people living with HIV? Estimates from four countries in East and Southern Africa

Background

Substantial falls in the mortality of people living with HIV (PLWH) have been observed since the introduction of antiretroviral therapy (ART) in sub-Saharan Africa. However, access and uptake of ART have been variable in many countries. We report the excess deaths observed in PLWH before and after the introduction of ART. We use data from five longitudinal studies in Malawi, South Africa, Tanzania, and Uganda, members of the network for Analysing Longitudinal Population-based HIV/AIDS data on Africa (ALPHA).

Methods

Individual data from five demographic surveillance sites that conduct HIV testing were used to estimate mortality attributable to HIV, calculated as the difference between the mortality rates in PLWH and HIV-negative people. Excess deaths in PLWH were standardized for age and sex differences and summarized over periods before and after ART became generally available. An exponential regression model was used to explore differences in the impact of ART over the different sites.

Results

127,585 adults across the five sites contributed a total of 487,242 person years. Before the introduction of ART, HIV-attributable mortality ranged from 45 to 88 deaths per 1,000 person years. Following ART availability, this reduced to 14–46 deaths per 1,000 person years. Exponential regression modeling showed a reduction of more than 50% (HR =0.43, 95% CI: 0.32–0.58), compared to the period before ART was available, in mortality at ages 15–54 across all five sites.

Discussion

Excess mortality in adults living with HIV has reduced by over 50% in five communities in sub-Saharan Africa since the advent of ART. However, mortality rates in adults living with HIV are still 10 times higher than in HIV-negative people, indicating that substantial improvements can be made to reduce mortality further. This analysis shows differences in the impact across the sites, and contrasts with developed countries where mortality among PLWH on ART can be similar to that of the general population. Further research is urgently needed to establish why the different impacts on mortality were observed and how the care and treatment programmes in these countries can be more effective in reducing mortality further.

Predictors of sexual debut among young adolescents in Nairobi's informal settlements

CONTEXT

There is a need to better understand the various social, psychosocial and behavioral factors associated with sexual activity among young adolescents in various settings in Sub-Saharan Africa.

METHODS

Data were drawn from Wave 1 (2007-2008) and Wave 2 (2009) of the Transition to Adulthood study, which collected information about key markers of the transition to adulthood and social, demographic and psychosocial characteristics of male and female youth living in two informal settlements in Nairobi, Kenya. Logistic regression analyses were used to examine variables associated with experience of sexual debut by Wave 2 among youth who were aged 12-16 and sexually inexperienced at Wave 1.

RESULTS

Of the 1,754 youth in the sample, 92 experienced sexual debut between survey waves. For both males and females, sexual debut was positively associated with having permanently dropped out of school (odds ratios, 6.9 and 21.8, respectively), having never attended school (8.6 and 39.4) and having experienced severe family dysfunction (2.8 and 5.7). Lack of parental supervision was a predictor of sexual debut among males only (10.1), whereas low aspiration was a predictor among females only (10.4). Surprisingly, young women, as well as men, who did not have high self-esteem were less likely than those who did to initiate first sex between waves (0.4 and 0.3).

CONCLUSIONS

Study findings underscore the importance of school attendance, family dysfunction, parental supervision and self-esteem in driving sexual behavior in this age-group. Further studies are warranted to elucidate how these factors can be addressed in prevention programs for young adolescents.

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).

Low rates of repeat HIV testing despite increased availability of antiretroviral therapy in rural Tanzania: findings from 2003-2010

Background

HIV counselling and testing (HCT) services can play an important role in HIV prevention by encouraging safe sexual behaviours and linking HIV-infected clients to antiretroviral therapy (ART). However, regular repeat testing by high-risk HIV-negative individuals is important for timely initiation of ART as part of the ‘treatment as prevention’ approach.

Aim

To investigate HCT use during a round of HIV serological surveillance in northwest Tanzania in 2010, and to explore rates of repeat testing between 2003 and 2010.

Methods

HCT services were provided during the fourth, fifth and sixth rounds of serological surveillance in 2003–2004 (Sero-4), 2006–2007 (Sero-5) and 2010 (Sero-6). HCT services have also been available at a government-run health centre and at other clinics in the study area since 2005. Questionnaires administered during sero-surveys collected information on socio-demographic characteristics, sexual behaviour and reported previous use of HCT services.

Results

The proportion of participants using HCT increased from 9.4% at Sero-4 to 16.6% at Sero-5 and 25.5% at Sero-6. Among participants attending all three sero-survey rounds (n = 2,010), the proportions using HCT twice or more were low, with 11.1% using the HCT service offered at sero-surveys twice or more, and 25.3% having tested twice or more if reported use of HCT outside of sero-surveys was taken into account. In multivariable analyses, individuals testing HIV-positive were less likely to repeat test than individuals testing HIV-negative (aOR 0.17, 95% CI 0.006–0.52).

Discussion/Conclusions

Although HCT service use increased over time, it was disappointing that the proportions ever testing and ever repeat-testing were not even larger, considering the increasing availability of HCT and ART in the study area. There was some evidence that HIV-negative people with higher risk sexual behaviours were most likely to repeat test, which was encouraging in terms of the potential to pick-up those at greatest risk of HIV-infection.

Updates to the Spectrum/Estimation and Projection Package (EPP) model to estimate HIV trends for adults and children

BACKGROUND

The Spectrum and Estimation and Projection Package (EPP) programs are used to estimate key HIV indicators based on HIV surveillance and surveys, programme statistics and epidemic patterns. 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 preventing mother to child transmission (PMTCT) and the impact of antiretroviral treatment on survival.

METHODS

The Joint United Nations Programme on HIV and AIDS (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. The latest updates described here were used in the 2011 round of global estimates.

RESULTS

Spectrum and EPP have now been combined into one software package to enhance ease of use and ensure consistent data and assumptions for the curve fitting and indicator estimations. Major enhancements to the methods include a new adult model that tracks the HIV+ population by CD4 count; new patterns describing child survival by time of infection (perinatally, <6 months, 7-12 months and 12+ months after birth); a more detailed estimate of mother-to-child transmission that includes differential transmission rates by CD4 count of the mother, the effects of incident infections and new prophylaxis options; and new procedures to estimate uncertainty ranges around regional estimates.

CONCLUSIONS

The revised model and software facilitate the preparation of new HIV estimates and use new data to address emerging needs for better information on need for treatment among adults and children.

Using age-specific mortality of HIV infected persons to predict anti-retroviral treatment need: a comparative analysis of data from five African population-based cohort studies

OBJECTIVES

To present a simple method for estimating population-level anti-retroviral therapy (ART) need that does not rely on knowledge of past HIV incidence.

METHODS

A new approach to estimating ART need is developed based on calculating age-specific proportions of HIV-infected adults expected to die within a fixed number of years in the absence of treatment. Mortality data for HIV-infected adults in the pre-treatment era from five African HIV cohort studies were combined to construct a life table, starting at age 15, smoothed with a Weibull model. Assuming that ART should be made available to anyone expected to die within 3 years, conditional 3-year survival probabilities were computed to represent proportions needing ART. The build-up of ART need in a successful programme continuously recruiting infected adults into treatment as they age to within 3 years of expected death was represented by annually extending the conditional survival range.

RESULTS

The Weibull model: survival probability in the infected state from age 15 = exp(-0.0073 × (age - 15)(1.69)) fitted the pooled age-specific mortality data very closely. Initial treatment need for infected persons increased rapidly with age, from 15% at age 20-24 to 32% at age 40-44 and 42% at age 60-64. Overall need in the treatment of naïve population was 24%, doubling within 5 years in a programme continually recruiting patients entering the high-risk period for dying.

CONCLUSION

A reasonable projection of treatment need in an ART naive population can be made based on the age and gender profile of HIV-infected people.

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.

The impact of antiretroviral therapy on adult mortality in rural Tanzania

OBJECTIVE

To describe the impact of antiretroviral therapy (ART) on mortality rates among adults participating in an HIV community cohort study in north-west Tanzania.

METHODS

Serological and demographic surveillance rounds have been undertaken in a population of approximately 30,000 people since 1994. Free HIV care including ART has been available since 2005. Event history analysis was used to compare mortality rates among HIV-negative and HIV-positive adults in the 5-year period before and after the introduction of ART. Crude and adjusted hazard ratios were calculated using exponential regression models. Interaction between time period and HIV status was assessed to investigate whether there was a non-linear relationship between these two variables.

RESULTS

Male and female mortality patterns varied over the pre- and post-ART period. In women, the crude death rate fell for both HIV negatives and HIV positives hazard rate ratio (HRR = 0.71; 95%CI 0.51-0.99 and HRR = 0.68; 95%CI: 0.46-0.99, respectively). For men, the mortality among the HIV negatives increased (HRR = 1.47; 95%CI: 1.06-2.03) while the decline in mortality among the HIV positives (HRR = 0.77; 95%CI 0.52-1.13) was not statistically significant. The largest decrease in HIV-positive mortality over the two periods was among the 30- to 44-year-old age group for women and among the 45- to 59-year-old age group for men.

CONCLUSION

There has been a modest effect on mortality in the study population following the introduction of free ART 5 years ago. Improving access to treatment and placing greater focus on retaining individuals on treatment are essential if the full potential of treatment for reducing HIV-related mortality is to be realised.

Children who acquire HIV infection perinatally are at higher risk of early death than those acquiring infection through breastmilk: a meta-analysis

BACKGROUND

Assumptions about survival of HIV-infected children in Africa without antiretroviral therapy need to be updated to inform ongoing UNAIDS modelling of paediatric HIV epidemics among children. Improved estimates of infant survival by timing of HIV-infection (perinatally or postnatally) are thus needed.

METHODOLOGY/PRINCIPAL FINDINGS

A pooled analysis was conducted of individual data of all available intervention cohorts and randomized trials on prevention of HIV mother-to-child transmission in Africa. Studies were right-censored at the time of infant antiretroviral initiation. Overall mortality rate per 1000 child-years of follow-up was calculated by selected maternal and infant characteristics. The Kaplan-Meier method was used to estimate survival curves by child's HIV infection status and timing of HIV infection. Individual data from 12 studies were pooled, with 12,112 children of HIV-infected women. Mortality rates per 1,000 child-years follow-up were 39.3 and 381.6 for HIV-uninfected and infected children respectively. One year after acquisition of HIV infection, an estimated 26% postnatally and 52% perinatally infected children would have died; and 4% uninfected children by age 1 year. Mortality was independently associated with maternal death (adjusted hazard ratio 2.2, 95%CI 1.6-3.0), maternal CD4<350 cells/ml (1.4, 1.1-1.7), postnatal (3.1, 2.1-4.1) or peri-partum HIV-infection (12.4, 10.1-15.3).

CONCLUSIONS/RESULTS

These results update previous work and inform future UNAIDS modelling by providing survival estimates for HIV-infected untreated African children by timing of infection. We highlight the urgent need for the prevention of peri-partum and postnatal transmission and timely assessment of HIV infection in infants to initiate antiretroviral care and support for HIV-infected children.

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.

Net survival of perinatally and postnatally HIV-infected children: a pooled analysis of individual data from sub-Saharan Africa

BACKGROUND

Previously, HIV epidemic models have used a double Weibull curve to represent high initial and late mortality of HIV-infected children, without distinguishing timing of infection (peri- or post-natally). With more data on timing of infection, which may be associated with disease progression, a separate representation of children infected early and late was proposed.

METHODS

Paediatric survival post-HIV infection without anti-retroviral treatment was calculated using pooled data from 12 studies with known timing of HIV infection. Children were grouped into perinatally or post-natally infected. Net mortality was calculated using cause-deleted life tables to give survival as if HIV was the only competing cause of death. To extend the curve beyond the available data, children surviving beyond 2.5 years post infection were assumed to have the same survival as young adults. Double Weibull curves were fitted to both extended survival curves to represent survival of children infected perinatally or through breastfeeding.

RESULTS

Those children infected perinatally had a much higher risk of dying than those infected through breastfeeding, even allowing for background mortality. The final-fitted double Weibull curves gave 75% survival at 5 months after infection for perinatally infected, and 1.1 years for post-natally infected children. An estimated 25% of the early infected children would still be alive at 10.6 years compared with 16.9 years for those infected through breastfeeding.

CONCLUSIONS

The increase in available data has enabled separation of child mortality patterns by timing of infection allowing improvement and more flexibility in modelling of paediatric HIV infection and survival.

Reported number of sexual partners: comparison of data from four African longitudinal studies

OBJECTIVE

To compare reported numbers of sexual partners in Eastern and Southern Africa.

METHODS

Sexual partnership data from four longitudinal population-based surveys (1998-2007) in Zimbabwe, Uganda and South Africa were aggregated and overall proportions reporting more than one lifetime sexual partner calculated. A lexis-style table was used to illustrate the average lifetime sexual partners by site, sex, age group and birth cohort. The male-to-female ratio of mean number of partnerships in the last 12 months was calculated by site and survey. For each single year of age, the proportion sexually active in the past year, the mean number of partners in the past year and the proportion with more than one partner in the past year were calculated.

RESULTS

Over 90% of men and women between 25 and 45 years of age reported being sexually active during the past 12 months, with most reporting at least one sexual partner. Overall, men reported higher numbers of lifetime sexual partners and partners in the last year than women. The male-to-female ratio of mean partnerships in the last year ranged from 1.41 to 1.86. In southern African cohorts, individuals in later birth cohorts reported fewer sexual partners and a lower proportion reported multiple partnerships compared with earlier birth cohorts, whereas these behavioural changes were not observed in the Ugandan cohorts. Across the four sites, reports of sexual partnerships followed a similar pattern for each sex.

CONCLUSIONS

The longitudinal results show that reductions in the number of partnerships were more evident in southern Africa than in Uganda.

Influence of timing of sexual debut and first marriage on sexual behaviour in later life: findings from four survey rounds in the Kisesa cohort in northern Tanzania

OBJECTIVES

To evaluate quality of sexual debut and first marriage data, measure trends and study the association of risky sexual behaviour in youth with adult risk behaviour.

METHODS

Reports on age at first sex (AFS) and age at first marriage (AFM) from the Kisesa cohort study, 1994-2004, were evaluated for consistency and used to describe trends in median age-at-event and time spent single but sexually active in different birth cohorts. The association of these variables with marital stability and numbers of partners at later ages was explored using statistical regression techniques.

RESULTS

AFS and AFM were inconsistently reported by 32% and 33% of respondents, respectively, but there was no general tendency to report lower or higher ages at a later report date. In 10-year birth cohorts born between 1950-9 and 1980-9, male median AFS declined from 18.1 to 17.0 years and female median AFM rose from 16.2 to 16.6 years. Young people of both sexes currently spend longer sexually active but unmarried than previously. Early marriage is statistically associated with remarriage and polygamy; longer time between sexual debut and marriage is associated with higher numbers of partners at later stages of life.

CONCLUSION

Inconsistent reporting of age-at-event introduces noise but does not bias estimates of population level indicators. Lengthening time spent single and sexually active suggests that men and women entering first marriage will have been exposed to increased numbers of non-marital partners. Successful youth interventions may also influence adult behaviour.

Trends in marriage and time spent single in sub-Saharan Africa: a comparative analysis of six population-based cohort studies and nine Demographic and Health Surveys

OBJECTIVES

To describe trends in age at first sex (AFS), age at first marriage (AFM) and time spent single between events and to compare age-specific trends in marital status in six cohort studies.

METHODS

Cohort data from Uganda, Tanzania, South Africa, Zimbabwe and Malawi and Demographic and Health Survey (DHS) data from Uganda, Tanzania and Zimbabwe were analysed. Life table methods were used to calculate median AFS, AFM and time spent single. In each study, two surveys were chosen to compare marital status by age and identify changes over time.

RESULTS

Median AFM was much higher in South Africa than in the other sites. Between the other populations there were considerable differences in median AFS and AFM (AFS 17-19 years for men and 16-19 years for women, AFM 21-24 years and 18-19 years, respectively, for the 1970-9 birth cohort). In all surveys, men reported a longer time spent single than women (median 4-7 years for men and 0-2 years for women). Median years spent single for women has increased, apart from in Manicaland. For men in Rakai it has decreased slightly over time but increased in Kisesa and Masaka. The DHS data showed similar trends to those in the cohort data. The age-specific proportion of married individuals has changed little over time.

CONCLUSIONS

Median AFS, AFM and time spent single vary considerably among these populations. These three measures are underlying determinants of sexual risk and HIV infection, and they may partially explain the variation in HIV prevalence levels between these populations.

Non-response bias in estimates of HIV prevalence due to the mobility of absentees in national population-based surveys: a study of nine national surveys

Objectives:

To measure the bias in national estimates of HIV prevalence in population-based surveys caused by mobility and refusal to test.

Methods:

Data from nine demographic and health surveys and AIDS indicator surveys were used. Non-responders were divided into three groups: (i) “refusals” who were interviewed but not tested; (ii) “refusals” who were present in the household but not interviewed or tested; and (iii) “absentees” who were absent from the household. Correction for HIV status was made for the non-responders using multiple imputation methods with logistic regression models based on a common set of household-level and individual-level sociodemographic and behavioural factors for those tested and stratified by mobility status.

Results:

The non-response groups were corrected to have higher risks of HIV than those who participated in the HIV tests, although these were only detected to be statistically significant in some of the countries. In Lesotho, the corrected prevalence for the absent household members was significantly higher than for those who were present in the household. However, the adjusted prevalences differed by less than a percentage point from the prevalences observed among those who were tested, so the overall effects of non-response on national estimates of HIV prevalence are minimal.

Conclusions:

The results indicate that the mobility of absentees does not substantially bias estimates of HIV prevalence from population-based surveys. None the less, if levels of non-response are high or if non-responders differ greatly from those who participate in HIV testing with respect to HIV status, non-response could still bias national estimates of HIV prevalence.

The effects of high HIV prevalence on orphanhood and living arrangements of children in Malawi, Tanzania, and South Africa

Using longitudinal data from three demographic surveillance systems (DSS) and a retrospective cohort study, we estimate levels and trends in the prevalence and incidence of orphanhood in South Africa, Tanzania, and Malawi in the period 1988-2004. The prevalence of maternal, paternal, and double orphans rose in all three populations. In South Africa - where the HIV epidemic started later, has been very severe, and has not yet stabilized - the incidence of orphanhood among children is double that of the other populations. The living arrangements of children vary considerably between the populations, particularly in relation to fathers. Patterns of marriage, migration, and adult mortality influence the living and care arrangements of orphans and non-orphans. DSS data provide new insights into the impact of adult mortality on children, challenging several widely held assumptions. For example, we find no evidence that the prevalence of child-headed households is significant or has increased in the three study areas.

Projecting the demographic impact of AIDS and the number of people in need of treatment: updates to the Spectrum projection package

BACKGROUND

In the Joint United Nations Programme on HIV/AIDS (UNAIDS) approach to HIV and AIDS estimates, estimates of adult prevalence produced by the Estimation and Projection Package (EPP) or the Workbook are transferred to Spectrum to estimate the consequences of the HIV/AIDS epidemic, including the number of people living with HIV by age and sex, new infections, AIDS deaths, AIDS orphans, treatment needs, and the impact of treatment on survival.

METHODS

The UNAIDS Reference Group on Estimates, Models and Projections recommends updates to the methodology and assumptions based on the latest research findings and international policy and programme guidelines. The latest update to Spectrum has been used in the 2005 round of global estimates.

RESULTS

Several new features have been added to Spectrum in the past two years. New patterns of the age distribution of prevalence over time are based on the latest survey data. A more detailed treatment of mother to child transmission of HIV is now based on information about current breastfeeding practices, treatment options offered to prevent mother to child transmission (PMTCT), infant feeding options, and the percentage or number of pregnant women accessing PMTCT services. A new section on child survival includes the effects of cotrimoxazole and ART on child survival. Projections can now be calibrated with national survey data. A new set of outputs is provided for all adults over the age of 15 in addition to the traditional 15-49 age group. New outputs are now available to show plausibility bounds and regional estimates for key indicators.

CONCLUSIONS

The latest update to the Spectrum program is intended to incorporate the latest research findings and provide new outputs needed by national and international planners.

HIV and mortality of mothers and children: evidence from cohort studies in Uganda, Tanzania, and Malawi

BACKGROUND

The steady decline in child mortality observed in most African countries through the 1960s, 1970s, and 1980s has stalled in many countries in the 1990s because of the AIDS epidemic. However, the census and household survey data that generally are used to produce estimates of child mortality do not permit precise measures of the adverse effect of HIV on child mortality.

METHODS

To calculate excess risks of child mortality as the result of maternal HIV status, we used pooled data from 3 longitudinal community-based studies that classified births by the mother's HIV status. We also estimated excess risks of child death caused by increased mortality among mothers. The joint effects of maternal HIV status and maternal survival were quantified using multivariate techniques in a survival analysis.

RESULTS

Our analysis shows that the excess risk of death associated with having an HIV-positive mother is 2.9 (95% confidence interval = 2.3-3.6), and this effect lasts throughout childhood. The excess risk associated with a maternal death is 3.9 (2.8-5.5) in the 2-year period centered on the mother's death, with children of both infected and uninfected mothers experiencing higher mortality risks at this time.

CONCLUSION

HIV impacts on child mortality directly through transmission of the virus to newborns by infected mothers and indirectly through higher child mortality rates associated with a maternal death.

Estimating the net effect of HIV on child mortality in African populations affected by generalized HIV epidemics

For a given prevalence, HIV has a relatively higher impact on child mortality when mortality from other causes is low. To project the effect of the epidemic on child mortality, it is necessary to estimate a realistic schedule of "net" age-specific mortality rates that would operate if HIV were the only cause of child death observable. We assume that this net pattern would be independent of mortality from other causes. We used African studies that measured the survival of HIV-infected children (direct data) or survival of children of HIV-infected mothers (indirect data). We developed a mathematic procedure to estimate the mortality of infected children from indirect data sources and obtained net HIV mortality patterns for each study population. The net age-specific HIV mortality pattern for infected children can be described by a double Weibull curve fitted to empiric data; this gives a functional representation of age-specific mortality rates that decline after infancy and rise in the preteens. The fitted curve that we would expect if HIV were the only effective cause of death shows 67% net survival at 1 year and 39% at 5 years. The curve also predicts 13% net survival at 10 years using constraints based on survival of infected adults.

HIV impact on mother and child mortality in rural Tanzania

Child mortality in Tanzania rose from 137 per 1000 in 1992-1996 to 147 per 1000 in 1995-1999. Impact of HIV on child mortality is analyzed in a longitudinal community-based study in Kisesa ward, Mwanza region. HIV data on 4273 mothers from 3 rounds of serologic testing are linked to survival information for 6049 children born between 1994 and 2001, contributing 10,002 person-years of observation and 584 child deaths. Impacts of maternal survival and HIV status on child mortality are assessed using hazard analysis. Infant mortality for children of HIV-positive mothers was 158 per 1000 live births compared with 79 per 1000 for children of uninfected mothers; by age 5, child mortality risks were 270 per 1000 live births and 135 per 1000, respectively. Fifty-one deaths were observed among child-bearing women, 14 to HIV-positive mothers. Infant mortality among children whose mothers died was 489 per 1000 live births compared with 84 per 1000 for children of surviving mothers. Maternal death effects were statistically independent of HIV status. Allowing for age, sex, twinning, birth interval, maternal education, and residence, the child death hazard ratio for maternal HIV infection was 2.3 (1.7-3.3); hazard ratio associated with maternal death was 4.8 (2.7-8.4). The HIV-attributable fraction of infant mortality is 8.3% in a population in which prevalence among women giving birth is around 6.2%.

The in vitro resistance of canine staphylococci to trimethoprim and sulphamethoxazole alone and in combination

The in vitro resistance of 40 strains of Staphylococcus aureus isolated from dogs to trimethoprim, sulphamethoxazole and co-trimoxazole (SXT) was assessed using the disc diffusion technique on Diagnostic Sensitivity Test Agar (DSTA), DSTA with 5% lysed horse blood (DSTA + B), IsoSensitest Agar (ISTA) and Wellcotest Sensitivity Test Agar (WSTA). When sensitivity was based on a zone width of greater than or equal to 4 mm all 40 strains were sensitive to SXT on DSTA + B and ISTA, 39 were sensitive on WSTA while only 31 (77.5%) were sensitive on DSTA. A comparison of the results obtained for each strain for trimethoprim and sulphamethoxazole with those obtained with the Oxford strain of S. aureus and using a scheme for interpretation recommended by Garrod & O'Grady (1971) indicated that the proportion of strains classed as sensitive for therapeutic purposes was 5%, 55%, 47.5% and 15% respectively on DSTA, DSTA + B, ISTA and WSTA.