Emma Slaymaker

Sexual behaviour in context: a global perspective.

Although Claudia Garcia-Moreno and colleagues acknowledge that intimate-partner violence is a global health-care problem they report that educational status does not explain differences in the prevalence of intimate-partner violence between the countries the research team visited. However other studies suggest conflicting results. Thompson and colleagues studied 3568 women aged 18--64 years in the USA and showed that the rates of intimatepartner violence were higher for women with less education. In another study Maziak reported that poor education was one important correlate of physical abuse in 412 Syrian women. The association between female educational status and intimate-partner violence is also documented in a review article by Jewkes. According to this study high educational status of women was associated with low levels of violence in some countries whereas in others the aforementioned relation followed an inverted U-shape pattern with low violence rates at the lowest and highest educational levels. (excerpt)Research aimed at investigating sexual behaviour and assessing interventions to improve sexual health has increased in recent decades. The resulting data, despite regional differences in quantity and quality, provide a historically unique opportunity to describe patterns of sexual behaviour and their implications for attempts to protect sexual health at the beginning of the 21st century. In this paper we present original analyses of sexual behaviour data from 59 countries for which they were available. The data show substantial diversity in sexual behaviour by region and sex. No universal trend towards earlier sexual intercourse has occurred, but the shift towards later marriage in most countries has led to an increase in premarital sex, the prevalence of which is generally higher in developed countries than in developing countries, and is higher in men than in women. Monogamy is the dominant pattern everywhere, but having had two or more sexual partners in the past year is more common in men than in women, and reported rates are higher in industrialised than in non-industrialised countries. Condom use has increased in prevalence almost everywhere, but rates remain low in many developing countries. The huge regional variation indicates mainly social and economic determinants of sexual behaviour, which have implications for intervention. Although individual behaviour change is central to improving sexual health, efforts are also needed to address the broader determinants of sexual behaviour, particularly those that relate to the social context. The evidence from behavioural interventions is that no general approach to sexual-health promotion will work everywhere and no single-component intervention will work anywhere. Comprehensive behavioural interventions are needed that take account of the social context in mounting individual-level programmes, attempt to modify social norms to support uptake and maintenance of behaviour change, and tackle the structural factors that contribute to risky sexual behaviour.

Age at first sex: understanding recent trends in African demographic surveys

Objectives: To describe recent trends in age at first sex in African countries, identifying and making due allowances for a variety of common reporting errors. Methods: Demographic and Health Surveys (DHS) data from six African countries conducting three or more surveys since 1985 were analysed using survival analysis techniques, combining information on virginity status and retrospective reporting of age at first sex. Hazard analysis was used to separate the effects of reporting error and compositional change and to estimate true changes in sexual debut over time. A multistate life table analysis incorporating transition to first marriage allowed cohorts to be classified according to person years spent as virgins, as sexually active unmarried, and married. Results: Intersurvey comparisons generally suggested a slow secular rise in age at first sex. However, tracing birth cohorts between surveys revealed inconsistencies—median ages reported by female members of a birth cohort in their teens were generally higher than those reported when they reached their twenties, even when allowing for residence and education changes—probably a result of young, sexually active women denying they had ever had sex. Male birth cohorts tend to display the opposite kind of bias. Conclusions: Uganda, Kenya, and Ghana have experienced a more pronounced and unambiguous decline in premarital sexual activity than Tanzania, Zambia, and Zimbabwe, with statistically significant increases in age at first sex. In addition, Uganda has maintained a very short interval between onset of sexual activity and marriage for both sexes.

Clients of sex workers in different regions of the world: hard to count

Objectives: To estimate the proportion of the male population that reports having paid for sex in different regions. Methods: Clients of sex workers were identified from representative samples of men asked in face-to-face interviews whether they had had sex in exchange for money or whether they had paid for sex, in the last 12 months. A total of 78 national household surveys and nine city based surveys were selected for inclusion. Where such surveys were not available, results of behavioural surveillance surveys and of research studies were also used. Using national estimates, a median percentage of men who reported paying for sex was calculated for each region. Results: The median percentage of men who exchanged sex for money in the last 12 months in all regions was around 9–10%, with estimates from 13% to 15% in Central African region, 10 to 11% in Eastern and southern Africa, and 5–7% in Asia and Latin America. Estimates for men who paid sex were much lower at around 2–3% with ranges from 7% in the South African region to 1% in Asia and West Africa. Conclusions: Although errors of measurement and critical issues of definitions and interpretation exist, this compilation represents a first attempt to obtain reasonably coherent estimates of the proportion of men who were clients of sex workers at regional level. Large discrepancies between regions were found. Further improvements in national estimates will be critical to monitor coverage of HIV prevention programmes for sex workers and clients, and to improve estimates of national HIV infection prevalence levels in low and concentrated HIV epidemics.

A critique of international indicators of sexual risk behaviour

Objectives: To investigate whether the indicators of sexual risk behaviour, defined by UNAIDS for use among members of general populations, have been found as risk factors, to examine how information on sexual behaviour is collected and summarised in order to calculate the indicators, and to look for possible sources of error in the data and in interpretation of those indicators. Methods: The literature on risk factors for HIV infection was reviewed. Indicators were calculated for countries where data were available for two or more points in time. Results: Indicators of sexual behaviour describe behaviours that are relevant to HIV risk and that are amenable to change. These behaviours do not correspond closely to the individual risk factors for HIV infection that have been identified in observational studies. Conclusions: Although potential errors of both measurement and interpretation exist, most of the indicators currently defined can fulfil their purpose, providing they are used with caution. Many of the indicators should not be interpreted in isolation but need supporting information to make sense of trends or differences between groups. Much of this information is provided by other indicators. The source of the data used to calculate the indicator is potentially important and should always be provided with indicator estimates. Some estimate of the accuracy of the estimate, either by means of confidence intervals or the number of respondents, should be given.

Mortality trends in the era of antiretroviral therapy: evidence from the Network for Analysing Longitudinal Population based HIV/AIDS data on Africa (ALPHA)

Background:The rollout of antiretroviral therapy (ART) is one of the largest public health interventions in Eastern and Southern Africa of recent years. Its impact is well described in clinical cohort studies, but population-based evidence is rare. Methods:We use data from seven demographic surveillance sites that also conduct community-based HIV testing and collect information on the uptake of HIV services. We present crude death rates of adults (aged 15–64) for the period 2000–2011 by sex, HIV status, and treatment status. Parametric survival models are used to estimate age-adjusted trends in the mortality rates of people living with HIV (PLHIV) before and after the introduction of ART. Results:The pooled ALPHA Network dataset contains 2.4 million person-years of follow-up time, and 39114 deaths (6893 to PLHIV). The mortality rates of PLHIV have been relatively static before the availability of ART. Mortality declined rapidly thereafter, with typical declines between 10 and 20% per annum. Compared with the pre-ART era, the total decline in mortality rates of PLHIV exceeds 58% in all study sites with available data, and amounts to 84% for women in Masaka (Uganda). Mortality declines have been larger for women than for men; a result that is statistically significant in five sites. Apart from the early phase of treatment scale up, when the mortality of PLHIV on ART was often very high, mortality declines have been observed in PLHIV both on and off ART. Conclusion:The expansion of treatment has had a large and pervasive effect on adult mortality. Mortality declines have been more pronounced for women, a factor that is often attributed to womens greater engagement with HIV services. Improvements in the timing of ART initiation have contributed to mortality reductions in PLHIV on ART, but also among those who have not (yet) started treatment because they are increasingly selected for early stage disease.

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.

Updates to the Spectrum model to estimate key HIV indicators for adults and children

Background:The Spectrum program is used to estimate key HIV indicators for national programmes. The purpose of the study is to describe the key updates made to Spectrum in the last 2 years to produce the version used in the 2013 global estimates of HIV/AIDS. Methods:The United Nations Programme on HIV/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 data from surveys, census and special studies are used to estimate key parameter values for countries and regions. Results:Country-specific life tables prepared by the United National Population Division (UNPD) have been incorporated into Spectrums demographic projections replacing the model life tables used previously. This update includes revised estimates of non-AIDS life expectancy. Incidence among all adults 15–49 years generated from curve fitting to surveillance and survey data is now split by age using incidence rate ratios derived from Analysing Longitudinal Population-based HIV/AIDS data on Africa Network data for generalized epidemics. Methods for estimating the number of AIDS orphans have been updated to include the changing effects of PMTCT and antiretroviral therapy programmes. Procedures for estimating the number of adults eligible for treatment have been updated to reflect the 2013 WHO guidelines. Program data on AIDS mortality has been used to estimate prevalence trends in Argentina, Brazil and Mexico for the 2013 estimates. Conclusion:Spectrum was updated for the 2013 round of HIV estimates in order to support national programmes with improved methods and data to estimating national indicators.

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.

The role of behavioral data in HIV surveillance.

This paper reviews the ways in which data on sexual behavior can contribute to the understanding of HIV prevalence trends based on sentinel surveillance, building on work presented at a meeting on new strategies for HIV/AIDS surveillance in resource-constrained countries, held in Addis Ababa in January 2004.A key component of second-generation surveillance is the collection of data on the behaviors and background characteristics that may influence the course of the HIV epidemic in a population. However, the most appropriate methods for the collection and analysis of these data for various types of epidemic have yet to be established.A conceptual framework is presented outlining the relationships between background characteristics, behaviors and HIV infection. The different methods used to collect data on HIV infection, risk behaviors and background characteristics in generalized and concentrated epidemics are reviewed, including population-based surveys, and surveillance in high- and low-risk groups. The various biases inherent in different approaches are discussed. The implications of linking data at the individual and community levels are explored and recommendations made concerning appropriate analytical approaches, drawing on an example of a pilot study that linked biological and behavioral surveillance in Tanzanian antenatal clinics.The paper concludes with recommendations for the methods and frequency with which to collect the data required for second-generation HIV surveillance.

Trends in age at first sex in Uganda: evidence from Demographic and Health Survey data and longitudinal cohorts in Masaka and Rakai

Objectives: To derive the best possible estimates of trends in age at first sex (AFS) among successive cohorts of Ugandan men and women based on all the data available from the Demographic and Health Surveys (DHS) and cohort studies in Masaka and Rakai districts. Methods: The datasets from the DHS, Masaka cohort and Rakai cohort were analysed separately. Survival analysis methods were used to estimate median AFS for men and women born in the 1950s–1980s and to compute hazard ratios for first sex, comparing later cohorts with earlier cohorts. Results: The DHS and Masaka data showed an increase in AFS in women in the more recent birth cohorts compared with those born before 1970, but this was less apparent in the Rakai data. Successive male cohorts in Masaka appeared first to have an increased AFS which subsequently decreased, a trend that was also apparent (but not significant) in the DHS data. Younger men in Rakai had an earlier AFS than those born before 1980. Conclusions: Women in Uganda who were born after 1970 have, on average, had sex at a later age than those born earlier. For men, AFS has not changed consistently over the period in question. Differences between Masaka and Rakai may reflect socioeconomic differences. Most of the change in AFS occurred too late to have contributed to the initial decline in the incidence of HIV.