Jesus M Garcia-Calleja

Declines in HIV prevalence can be associated with changing sexual behaviour in Uganda, urban Kenya, Zimbabwe, and urban Haiti

Objective: To determine whether observed changes in HIV prevalence in countries with generalised HIV epidemics are associated with changes in sexual risk behaviour. Methods: A mathematical model was developed to explore the relation between prevalence recorded at antenatal clinics (ANCs) and the pattern of incidence of infection throughout the population. To create a null model a range of assumptions about sexual behaviour, natural history of infection, and sampling biases in ANC populations were explored to determine which factors maximised declines in prevalence in the absence of behaviour change. Modelled prevalence, where possible based on locally collected behavioural data, was compared with the observed prevalence data in urban Haiti, urban Kenya, urban Cote d’Ivoire, Malawi, Zimbabwe, Rwanda, Uganda, and urban Ethiopia. Results: Recent downturns in prevalence observed in urban Kenya, Zimbabwe, and urban Haiti, like Uganda before them, could only be replicated in the model through reductions in risk associated with changes in behaviour. In contrast, prevalence trends in urban Cote d’Ivoire, Malawi, urban Ethiopia, and Rwanda show no signs of changed sexual behaviour. Conclusions: Changes in patterns of HIV prevalence in urban Kenya, Zimbabwe, and urban Haiti are quite recent and caution is required because of doubts over the accuracy and representativeness of these estimates. Nonetheless, the observed changes are consistent with behaviour change and not the natural course of the HIV epidemic.

National population based HIV prevalence surveys in sub‐Saharan Africa: results and implications for HIV and AIDS estimates

Background: Sentinel surveillance among pregnant women attending antenatal clinics (ANCs) has been the main source of information on HIV trends in sub-Saharan Africa. These data have also been used to generate national HIV and AIDS estimates. New technologies and resources have allowed many countries to conduct national population based surveys that include HIV prevalence measurement, as an additional source of information on the AIDS epidemic. Methods: The authors reviewed the reports of 20 national population based surveys from 19 countries carried out in sub-Saharan Africa since 2001. They examined the sampling methodology, HIV testing and response rates, and female:male and urban:rural prevalence ratios. They also constructed adjusted prevalence scenarios assuming different relative risks for survey non-responders. Results: The national population based surveys vary considerably in quality, as reflected in the household response rate (ranging from 75.4% to 99.7%), women’s testing rate (ranging from 68.2% to 97.3%), and men’s testing rate (ranging from 62.2% to 95.4%), while for some surveys detailed response information is lacking. While 95% confidence intervals around the female:male and urban:rural prevalence ratios in individual countries are large, the median female:male ratio of the combined set of surveys results is 1.5 and the median urban:rural ratio 1.7. A scenario assuming that non-responders have twice the HIV prevalence of those who fully participated in the survey suggests that individual non-response could result in an adjusted HIV prevalence 1.03 to 1.34 times higher than the observed prevalence. Conclusions: Population based surveys can provide useful information on HIV prevalence levels and distribution. This information is being used to improve national HIV and AIDS estimates. Further refinements in data collection, analysis, and reporting, combined with high participation rates, can further improve HIV and AIDS estimates at national and regional level.

Lives saved by Global Fund-supported HIV/AIDS, tuberculosis and malaria programs: estimation approach and results between 2003 and end-2007

BackgroundSince 2003, the Global Fund has supported the scale-up of HIV/AIDS, tuberculosis and malaria control in low- and middle-income countries. This paper presents and discusses a methodology for estimating the lives saved through selected service deliveries reported to the Global Fund.MethodsGlobal Fund-supported programs reported, by end-2007, 1.4 million HIV-infected persons on antiretroviral treatment (ARV), 3.3 million new smear-positive tuberculosis cases detected in DOTS (directly observed TB treatment, short course) programs, and 46 million insecticide-treated mosquito nets (ITNs) delivered. We estimated the corresponding lives saved using adaptations of existing epidemiological estimation models.ResultsBy end-2007, an estimated 681,000 lives (95% uncertainty range 619,000-774,000) were saved and 1,097,000 (993,000-1,249,000) life-years gained by ARV. DOTS treatment would have saved 1.63 million lives (1.09 - 2.17 million) when compared against no treatment, or 408,000 lives (265,000-551,000) when compared against non-DOTS treatment. ITN distributions in countries with stable endemic falciparum malaria were estimated to have achieved protection from malaria for 26 million of child-years at risk cumulatively, resulting in 130,000 (27,000-232,000) under-5 deaths prevented.ConclusionsThese results illustrate the scale of mortality effects that supported programs may have achieved in recent years, despite margins of uncertainty and covering only selected intervention components. Evidence-based evaluation of disease impact of the programs supported by the Global Fund with international and in-country partners must be strengthened using population-level data on intervention coverage and demographic outcomes, information on quality of services, and trends in disease burdens recorded in national health information systems.

The 2005 Workbook: an improved tool for estimating HIV prevalence in countries with low level and concentrated epidemics

Objective: This paper describes improvements and updates to an established approach to making epidemiological estimates of HIV prevalence in countries with low level and concentrated epidemics. Methods: The structure of the software used to make estimates is briefly described, with particular attention to changes and improvements. Discussion: The approach focuses on identifying populations which, through their behaviour, are at high risk of infection with HIV or who are exposed through the risk behaviour of their sexual partners. Estimates of size and HIV prevalence of these populations allow the total number of HIV infected people in a country or region to be estimated. Major changes in the software focus on the move away from short term projections and towards developing an epidemiological curve that more accurately represents the change in prevalence of HIV over time. The software continues to provide an output file for use in the Spectrum software so as to estimate the demographic impact of HIV infection at country level.

Behavioural data as an adjunct to HIV surveillance data.

Background: Second generation surveillance for HIV aims to improve the validity and utility of routine serial HIV prevalence data. It includes the collection of data on sexual behaviour and sexually transmitted disease prevalence. Methods: This paper reviews the function of sexual behaviour data in HIV surveillance and the methods used to determine which behaviours are monitored and how changes in behaviour can be assessed. Results: Sexual behaviour data provide a poor predictor of the future spread of HIV, but these data can provide corroboration of changes in HIV incidence and assist in attributing changes to particular aspects of risk. Significance tests should be used to assess changes in behaviour, but this requires transparent reporting of methods and sample sizes. Conclusions: Collection of behavioural data will provide important retrospective information about the HIV epidemic progress and should not be neglected because of the focus on improving HIV sero-surveillance.

The workbook approach to making estimates and projecting future scenarios of HIV/AIDS in countries with low level and concentrated epidemics

This paper describes an approach to making estimates and short term projections of future scenarios of HIV/AIDS in countries with low level and concentrated epidemics. This approach focuses on identifying populations which through their behaviour are at higher risk of infection with HIV or who are exposed through the risk behaviour of their sexual partners. Estimates of the size and HIV prevalence of these populations allow the total number of HIV infected people in a country or region to be estimated. Subsequently, assumptions about the possible level and timing of saturation of HIV prevalence among each population can be used to explore future scenarios of HIV prevalence. The basic structure of the software used to make estimates and projections is described. This software includes a set of consistency and audit checks to help exclude unrealistic projections. The paper also discusses the strengths and weakness to this approach to making estimates and projections of HIV/AIDS in countries with low level and concentrated epidemics.

A global analysis of trends in the quality of HIV sero-surveillance.

Objective: To examine the quality of HIV sero-surveillance systems in countries by 2002, as well as trends between 1995 and 2002. Methods: The quality of countries’ surveillance systems was scored for five years: 1995, 1997, 1999, 2001, and 2002. Sero-surveillance data were compiled from the US Census Bureau’s HIV/AIDS Surveillance Database, the EuroHIV database, and from countries’ national HIV surveillance reports that were available to WHO/UNAIDS. The quality of systems was scored according to the level of the countries’ epidemic. Results: There has been a large variation in the quality of HIV surveillance systems across the 132 countries by type of the epidemic and over time from 1995 to 2002. Over the 1995–2002 period the number of countries with a fully implemented system decreased from 57 (43%) in 1995 to 48 (36%) in 2002. The proportion of countries with a fully implemented system was 58%, 34%, and 10% in countries with a generalised, concentrated, and low level epidemic, respectively. In the 53 countries with generalised epidemics the number of countries with a fully implemented system increased from 24 (45%) in 2001 to 31 (58%) in 2002. Conclusion: Many countries still have poor functioning HIV surveillance systems and require urgent strengthening. Countries should monitor and evaluate their own HIV surveillance systems and examine whether the systems are appropriate and adequate.

Advances and future directions in HIV surveillance in low- and middle-income countries.

Purpose of reviewTo present recent advances in HIV/AIDS surveillance methods in low- and middle-income countries. Recent findingsFrom 2001 to 2008, 30 low- and middle-income countries implemented national population-based surveys with HIV testing. Antenatal clinic HIV sentinel surveillance sites in sub-Saharan Africa increased from just over 1000 in 2003–2004 to almost 2500 in 2005–2006, becoming more representative of rural areas. Between 2003 and 2007, at least 122 behavioral surveys in low- and middle-income countries used respondent-driven sampling for surveillance among high-risk populations, although many countries with concentrated epidemics continue to have major sentinel surveillance gaps. Improvements have been made in modeling estimates of number of persons HIV infected, and systems are now in place to measure HIV drug resistance. However, the reliable monitoring of trends and the measuring of HIV incidence, morbidity, and mortality is still a challenge. SummaryIn the past 5 years, there have been substantial improvements in the quantity and quality of HIV surveillance studies, especially in the countries with high prevalence. Further efforts should be made in countries that lack fully implemented surveillance systems to improve HIV incidence, morbidity, and mortality surveillance and to use data more effectively.

The quality of sero-surveillance in low- and middle-income countries: status and trends through 2007

Objective: To examine the quality of HIV sero-surveillance systems in 127 low-income and middle-income countries by 2007, as well as gaps in data needed for reliable estimates of HIV prevalence and size of populations at risk for infection. Methods: The quality of countries’ surveillance systems was scored using information from 2001 through 2007. Sero-surveillance data were compiled from the US Census Bureau’s HIV/AIDS Surveillance Database, from countries’ national HIV surveillance reports available to UNAIDS, from demographic and health survey (DHS) data, from the scientific literature and from countries’ Estimation and Projection Programme (EPP) data files. The quality of systems was scored according to the classification of the epidemic in each country (generalised, concentrated or low-level). Result: The number of countries categorised as fully functioning in 2007 was 40. 43 countries were identified as partially functioning while 44 were categorised as poorly functioning. Low scores were most often attributed to a lack of recent data or data from appropriate risk groups. Conclusion: Many countries still have poorly functioning surveillance systems. The inclusion of HIV testing in national population-based surveys in recent years has resulted in some countries with generalised epidemics receiving higher coverage scores, but many countries with concentrated or low-level epidemics continue to lack data on high-risk populations.

Trends in HIV prevalence among young people in generalised epidemics: implications for monitoring the HIV epidemic

Background Countries measure trends in HIV incidence to assess the impact of HIV prevention and treatment programmes. Most countries have approximated trends in HIV incidence through modelled estimates or through trends in HIV prevalence among young people (aged 15–24 years) assuming they have recently become sexually active and have thus only been recently exposed to HIV. Methods Trends in HIV incidence are described and results are compared using three proxy measures of incidence: HIV prevalence among young women attending antenatal clinics (ANCs) in 22 countries; HIV prevalence among young male and female nationally representative household survey respondents in 14 countries; and modelled estimates of adult (ages 15–49 years) HIV incidence in 26 countries. The significance of changes in prevalence among ANC attendees and young survey respondents is tested. Results Among 26 countries, 25 had evidence of some decline in HIV incidence and 15 showed statistically significant declines in either ANC data or survey data. Only in Mozambique did the direction of the trend in young ANC attendees differ from modelled adult incidence, and in Mali and Zambia trends among young men differed from trends in adult incidence. The magnitude of change differed by method. Conclusions Trends in HIV prevalence among young people show encouraging declines. Changes in fertility patterns, HIV-infected children surviving to adulthood, and participation bias could affect future proxy measures of incidence trends.