Data Resource Profile: Network for Analysing Longitudinal Population-based HIV/AIDS data on Africa (ALPHA Network)

The Network for Analysing Longitudinal Population-based HIV/AIDS data on Africa (ALPHA Network) was established in 2005 and aims to: (i) broaden the evidence base on HIV epidemiology for informing policy; (ii) strengthen analytical capacity for HIV research; and (iii) foster collaboration between study sites. 1 All of the study sites participating in the ALPHA Network are independently managed and have their own scientific agendas and tailored research methodologies, but share a common interest in HIV epidemiology and its interactions with the socio-demographic characteristics of the populations they cover. The ALPHA Network study sites and their institutional affiliations are described in Table 1 , and their geographical distribution is shown in Figure 1 . Several of the ALPHA Network study sites have published site-specific profiles that contain more detail. 2–10 Most of the ALPHA Network study sites are also members of the INDEPTH Network of demographic surveillance sites [ http://www.indepth-network.org/ ]. Location of the ALPHA member study sites. Description of the ALPHA Network study sites MRC/UVRI Research Unit on AIDS http://www.mrcuganda.org/research/research-site/kyamulibwa-field-station 1989: Annual 1989: Annual. Every 2 years from 2012 Medical Research Council HIV care and treatment clinic: 1990 Rakai Health Sciences Program, Uganda Virus Research Institute / Makerere University http://www.rhsp.org 1995: Every 12-16 months 1995: Every 12-16 months HIV care and treatment clinic: from 2004 to 2013 Magu Household Demographic Surveillance System Tazama Project, Tanzania National Institute for Medical Research http://www.tazamaproject.org/ 1994: 1-2 times per year 1994: Approx. every 3 years ANC, VCT and HIV treatment clinic at the Kisesa Health Centre: 2015 Malawi Epidemiology and Intervention Research Unit (MEIRU), London School of Hygiene and Tropical Medicine http://www.lshtm.ac.uk/eph/ide/research/kps/list 2002: Continuous HIV treatment facilities throughout the district: 2005 c Biomedical Research and Training Institute (Harare), and Imperial College (London) http://www.manicalandhivproject.org/ 1998: Every 2-3 years 2002: Every 2-3 years Africa Centre for Population Health www.africacentre.ac.za/ 2000: bi-annual 2003-2004: Annual Agincourt Health and Demographic Surveillance Site University of the Witwatersrand http://www.agincourt.co.za/ 1992: Annual 2010: One survey to date Chronic care patients at eight health facilities: 2013 African Population and Health Research Center http://aphrc.org/ 2002: Every 4 months 2007: One survey to date Ifakara Health and Demographic Suveillance System a Ifakara Health Institute http://www.ihi.or.tz/ 2007: Tri-annual up to 2012; bi-annual thereafter KEMRI/CDC Health and Demographic Surveillance System Kenya Medical Research Institute and the Centers for Disease Control http://www.kemri.org/ Siaya county in former Nyanza Province, Kenya 2001: Tri-annual 2007: Approx. every 3 years HIV treatment facility: from 2003 to 2008 MRC/UVRI Research Unit on AIDS http://www.mrcuganda.org/research/research-site/kyamulibwa-field-station 1989: Annual 1989: Annual. Every 2 years from 2012 Medical Research Council HIV care and treatment clinic: 1990 Rakai Health Sciences Program, Uganda Virus Research Institute / Makerere University http://www.rhsp.org 1995: Every 12-16 months 1995: Every 12-16 months HIV care and treatment clinic: from 2004 to 2013 Magu Household Demographic Surveillance System Tazama Project, Tanzania National Institute for Medical Research http://www.tazamaproject.org/ 1994: 1-2 times per year 1994: Approx. every 3 years ANC, VCT and HIV treatment clinic at the Kisesa Health Centre: 2015 Malawi Epidemiology and Intervention Research Unit (MEIRU), London School of Hygiene and Tropical Medicine http://www.lshtm.ac.uk/eph/ide/research/kps/list 2002: Continuous HIV treatment facilities throughout the district: 2005 c Biomedical Research and Training Institute (Harare), and Imperial College (London) http://www.manicalandhivproject.org/ 1998: Every 2-3 years 2002: Every 2-3 years Africa Centre for Population Health www.africacentre.ac.za/ 2000: bi-annual 2003-2004: Annual Agincourt Health and Demographic Surveillance Site University of the Witwatersrand http://www.agincourt.co.za/ 1992: Annual 2010: One survey to date Chronic care patients at eight health facilities: 2013 African Population and Health Research Center http://aphrc.org/ 2002: Every 4 months 2007: One survey to date Ifakara Health and Demographic Suveillance System a Ifakara Health Institute http://www.ihi.or.tz/ 2007: Tri-annual up to 2012; bi-annual thereafter KEMRI/CDC Health and Demographic Surveillance System Kenya Medical Research Institute and the Centers for Disease Control http://www.kemri.org/ Siaya county in former Nyanza Province, Kenya 2001: Tri-annual 2007: Approx. every 3 years HIV treatment facility: from 2003 to 2008 Notes: a The Ifakara DSS started in 1997 and covered a total of 25 villages in the Kilombero and Ulanga districts. In 2007, the DSS was extended with 5 urban areas of Ifakara town. This cohort profile pertains to the urban DSS only. HIV serosurveillance is done in two of five of the urban areas b In many instances the fieldwork is spread over multiple calendar years. We only report the start date. c Record linkage with HIV treatment facilities coincided with the rollout of ART. Prior to 2005, record linkage was done for TB-related work. Description of the ALPHA Network study sites MRC/UVRI Research Unit on AIDS http://www.mrcuganda.org/research/research-site/kyamulibwa-field-station 1989: Annual 1989: Annual. Every 2 years from 2012 Medical Research Council HIV care and treatment clinic: 1990 Rakai Health Sciences Program, Uganda Virus Research Institute / Makerere University http://www.rhsp.org 1995: Every 12-16 months 1995: Every 12-16 months HIV care and treatment clinic: from 2004 to 2013 Magu Household Demographic Surveillance System Tazama Project, Tanzania National Institute for Medical Research http://www.tazamaproject.org/ 1994: 1-2 times per year 1994: Approx. every 3 years ANC, VCT and HIV treatment clinic at the Kisesa Health Centre: 2015 Malawi Epidemiology and Intervention Research Unit (MEIRU), London School of Hygiene and Tropical Medicine http://www.lshtm.ac.uk/eph/ide/research/kps/list 2002: Continuous HIV treatment facilities throughout the district: 2005 c Biomedical Research and Training Institute (Harare), and Imperial College (London) http://www.manicalandhivproject.org/ 1998: Every 2-3 years 2002: Every 2-3 years Africa Centre for Population Health www.africacentre.ac.za/ 2000: bi-annual 2003-2004: Annual Agincourt Health and Demographic Surveillance Site University of the Witwatersrand http://www.agincourt.co.za/ 1992: Annual 2010: One survey to date Chronic care patients at eight health facilities: 2013 African Population and Health Research Center http://aphrc.org/ 2002: Every 4 months 2007: One survey to date Ifakara Health and Demographic Suveillance System a Ifakara Health Institute http://www.ihi.or.tz/ 2007: Tri-annual up to 2012; bi-annual thereafter KEMRI/CDC Health and Demographic Surveillance System Kenya Medical Research Institute and the Centers for Disease Control http://www.kemri.org/ Siaya county in former Nyanza Province, Kenya 2001: Tri-annual 2007: Approx. every 3 years HIV treatment facility: from 2003 to 2008 MRC/UVRI Research Unit on AIDS http://www.mrcuganda.org/research/research-site/kyamulibwa-field-station 1989: Annual 1989: Annual. Every 2 years from 2012 Medical Research Council HIV care and treatment clinic: 1990 Rakai Health Sciences Program, Uganda Virus Research Institute / Makerere University http://www.rhsp.org 1995: Every 12-16 months 1995: Every 12-16 months HIV care and treatment clinic: from 2004 to 2013 Magu Household Demographic Surveillance System Tazama Project, Tanzania National Institute for Medical Research http://www.tazamaproject.org/ 1994: 1-2 times per year 1994: Approx. every 3 years ANC, VCT and HIV treatment clinic at the Kisesa Health Centre: 2015 Malawi Epidemiology and Intervention Research Unit (MEIRU), London School of Hygiene and Tropical Medicine http://www.lshtm.ac.uk/eph/ide/research/kps/list 2002: Continuous HIV treatment facilities throughout the district: 2005 c Biomedical Research and Training Institute (Harare), and Imperial College (London) http://www.manicalandhivproject.org/ 1998: Every 2-3 years 2002: Every 2-3 years Africa Centre for Population Health www.africacentre.ac.za/ 2000: bi-annual 2003-2004: Annual Agincourt Health and Demographic Surveillance Site University of the Witwatersrand http://www.agincourt.co.za/ 1992: Annual 2010: One survey to date Chronic care patients at eight health facilities: 2013 African Population and Health Research Center http://aphrc.org/ 2002: Every 4 months 2007: One survey to date Ifakara Health and Demographic Suveillance System a Ifakara Health Institute http://www.ihi.or.tz/ 2007: Tri-annual up to 2012; bi-annual thereafter KEMRI/CDC Health and Demographic Surveillance System Kenya Medical Research Institute and the Centers for Disease Control http://www.kemri.org/ Siaya county in former Nyanza Province, Kenya 2001: Tri-annual 2007: Approx. every 3 years HIV treatment facility: from 2003 to 2008 Notes: a The Ifakara DSS started in 1997 and covered a total of 25 villages in the Kilombero and Ulanga districts. In 2007, the DSS was extended with 5 urban areas of Ifakara town. This cohort profile pertains to the urban DSS only. HIV serosurveillance is done in two of five of the urban areas b In many instances the fieldwork is spread over multiple calendar years. We only report the start date. c Record linkage with HIV treatment facilities coincided with the rollout of ART. Prior to 2005, record linkage was done for TB-related work. The population perspective offered by the study sites complements the evidence from HIV clinical cohorts and health facility-based studies; their longitudinal character is what sets them apart from cross-sectional serological surveys. The activities of the Network revolve around a series of thematic workshops that lay the foundations for both site-specific and pooled analyses. Topics that have been studied in the past include HIV incidence, 11 sexual behaviour, 12 orphaning and children’s living arrangements, 13 and fertility. 14 The monitoring of HIV-associated mortality has been and continues to be one of its focus areas. 15–17 The Network is also well positioned to evaluate the population-level effects of antiretroviral therapy (ART) scale-up, and member sites have recently extended their efforts to collect more and better data on the uptake of HIV diagnostic and AIDS care services. The ALPHA Network is a regular contributor to the United Nations Programme on HIV/AIDS (UNAIDS) Reference Group on Estimates, Modelling and Projections [ http://www.epidem.org ], which oversees the data and methods used for producing HIV estimates for most countries in the world, and to the modelling community through an agreement with the HIV Modelling Consortium [ http://www.hivmodelling.org/ ]. The ALPHA Network pools and harmonizes data from member sites that conduct demographic surveillance in populations that range from approximately 20 000 to 220 000 in size. Most study sites cover the entire population in one contiguous area, but some members conduct surveillance in multiple areas to represent distinct socioeconomic zones (e.g. Manicaland). Surveillance is generally conducted via household visits and interviews with one of the household members—sometimes referred to as proxy-respondents—who report on births, deaths and in- and out- movements in the household in the intercensal period. The Karonga demographic surveillance is an exception, and is done by means of village informants with an annual census to check on reporting completeness. 2 In most study sites, the enumerated population includes all resident members of households in the surveillance area. The two South African study sites (uMkhanyakude and Agincourt) are characterized by high levels of temporary or circulatory migration, and both resident and non-resident members of households are enumerated (non-resident household members are included in the ALPHA Network datasets for Agincourt only). 18,19 With the exception of the study sites in Nairobi and Ifakara, the ALPHA Network member sites are predominantly rural, and they all have relatively young age structures ( Figure 2 ). In some of the settings, the population age structure is marked by high levels of out-migration (e.g. Masaka and uMkhanyakude). Relative age distribution by study site, sex and HIV status, 2011. The ALPHA Network assembles data from different sources, including demographic surveillance, verbal autopsy interviews, serological and sexual behaviour surveys and individually-linked data from medical facilities. The starting date and intervals of data collection are summarized in Table 1 . Demographic surveillance generates data about residence episodes and the starting (birth and in-migration) and terminating (migration and death) events of residence episodes. Most study sites routinely follow up the report of deaths in the household with a verbal autopsy (VA) interview for determining the underlying and immediate causes of death. VA instruments were developed independently, and have over the years converged towards the standard VA questionnaire proposed by the World Health Organization (WHO). 20 VA questionnaires typically include retrospective questions about the HIV status of the deceased, and many study sites now also enquire about HIV services use. Along with the demographic surveillance, ALPHA Network study sites organize repeated population-based HIV serosurveys, using either home visits or temporary HIV testing centres to which residents are invited. HIV testing eligibility criteria vary across sites, and some of the study sites have restricted testing to a sample of the adult population (Nairobi and Agincourt). HIV testing protocols and participation rates vary between sites and over time. Prior to the availability of rapid HIV tests, test results were optionally returned to participants at the household or temporary clinic a few weeks later. In recent serosurveys, residents are usually given an opportunity to receive standard HIV testing and counselling (HTC) during the visit when specimens for a research test are collected. The Manicaland study has offered free HIV tests for diagnostic purposes at a local antenatal clinic. Some of the ALPHA Network members have published studies describing the HIV serosurveys, non-response in the HIV serosurveillance and associated bias in HIV prevalence estimates. 21–25 The serosurveys also create an opportunity to administer an individual interview on sexual behaviour, health services utilization etc. A few of the ALPHA Network sites have established record linkage between the demographic surveillance and medical facility data via a unique (set of) identifier(s) (e.g. Karonga, uMkhanyakude, Rakai and Masaka) and others, including Kisesa, Kisumu and Agincourt, have piloted probabilistic record linkage. 26 A more recent initiative, currently implemented in Agincourt and Kisesa, is to conduct the record linkage in the presence of the patient at the time that he or she visits the health facility. This protocol has the advantage that the patient can confirm his or her identity, which ensures better-quality matches. In addition, the presence of the patient offers an opportunity to seek informed consent for linking medical information to the demographic surveillance database. Linked medical facility data are used to retrieve information on HIV status, care and treatment services use, and in some cases also clinical markers of disease progression and viral suppression. Essential (input) data for estimating mortality and HIV incidence and prevalence are the residence episodes and HIV test results. These data are updated on a regular basis and, to that end, we have developed a series of metadata templates that are used to guide the study sites on the structure and attributes of the data they contribute to the ALPHA Network. Metadata templates have also been developed for parent-child links, fertility, respondent background characteristics, verbal autopsy data and self-reported and clinic data on the use of HIV care and treatment services. Metadata templates are available through the ALPHA Network website (see below). The allocation of person-time to HIV status (and treatment) categories is study-specific. In analyses of mortality, we generally classify time prior to the first recorded HIV test as HIV status unknown. Failure to do so would introduce downward bias in mortality estimates as only survivors can be tested. The time following a positive test remains positive until censoring or death. Studies often also allow for exposure time following a negative test in order to estimate mortality among HIV-negative individuals, but the period is kept sufficiently short to ensure that elevated mortality among seroconvertors does not introduce upward bias. Similar rules for imputing and stale-dating information are used in studies focusing on other personal attributes (e.g. marital status). Table 2 summarizes the person-years of exposure and number of deaths by HIV status and, for people living with HIV (PLHIV), the stage on the HIV care and treatment cascade. All sites measure HIV infection, ART initiation and death. Some of the study sites can also distinguish between seroconversion and the receipt of an HIV-positive diagnosis, between PLHIV who are in care and those who are not, and between those who ever interrupted treatment and those who have been on ART continuously. Descriptive statistics of the pooled ALPHA dataset, 1990–2011 a Notes: a Based on pooled ALPHA data from December 2014. b An individual can contribute to more than one population subgroup as he or she ages, is tested, or moves to the next stage on the HIV treatment cascade. Counts of individuals may be inflated by incomplete reconcilliation of internal migrations, but it not the person-years of exposure or the number of deaths . c A with a HIV status is for the study has a record of a negative or positive HIV with an HIV status may be of their own HIV status but their test have at a facility not to the study and a not to report their or ever HIV positive are those with a study record of or treatment Descriptive statistics of the pooled ALPHA dataset, 1990–2011 a Notes: a Based on pooled ALPHA data from December 2014. b An individual can contribute to more than one population subgroup as he or she ages, is tested, or moves to the next stage on the HIV treatment cascade. Counts of individuals may be inflated by incomplete reconcilliation of internal migrations, but it not the person-years of exposure or the number of deaths . c A with a HIV status is for the study has a record of a negative or positive HIV with an HIV status may be of their own HIV status but their test have at a facility not to the study and a not to report their or ever HIV positive are those with a study record of or treatment The of the study populations by HIV status is shown in Figure 2 . This that the of the HIV status information across study sites. These from in the eligibility criteria for HIV of and HIV testing participation In addition, some study sites retrieve HIV status information through record linkage with treatment facilities (see Table 1 ). The also the number of HIV-positive in they were not for participation in the Record linkage with treatment facilities can only HIV-positive and that to HIV prevalence in the prevalence of HIV is more from the serological surveys with a for non-response studies from ALPHA sites the of HIV on adult data from the members established that the of in the of ART was to that in including the of people at ages, and the of in the the age at was These estimates of the of PLHIV who are not treatment are in the which is the used by for and estimates of the HIV/AIDS of has the ALPHA Network to contribute evidence on the of and of HIV-positive and has that a can have as an on a of as the HIV the ALPHA Network member sites have population-level mortality following the of ART. rates among adult PLHIV across all study sites have more than from per in to in ( Table 2 ). in the of ART initiation have not only the mortality of PLHIV but also mortality of those who have not started ART they are for 3 that the mortality rates of PLHIV on ART were often high as treatment was a of patients with were treatment as it ART the mortality rates of PLHIV on ART and so the of deaths among PLHIV during the first months of treatment ( Figure 3 ). of statistics are of in the of treatment initiation and the clinical of The in Figure 3 also that a in the deaths to PLHIV among and a record of treatment deaths are not usually in and that is the ALPHA study sites an information and rates of adult PLHIV by treatment status, Masaka and mortality among PLHIV remains relatively in the among adult PLHIV per was more than times than the of HIV-negative per Table 2 ). autopsy studies from the ALPHA Network sites have that HIV and to for a share of deaths among which that HIV services use remains These studies also that PLHIV have elevated mortality rates from a range of including some that are not of among PLHIV have generally been for than for and that is to be associated with with HIV services. the of by the adult to for than for HIV at and mortality rates from other causes all contribute to ALPHA study sites have also evidence about HIV incidence in settings, and have been used to methods on 11 and methods on incidence to the by studies of so only one ALPHA has shown a population-level in HIV incidence associated with ART A of is on the ALPHA Network website ( ). The ALPHA Network assembles data from population-based HIV surveillance sites in Africa and is an for the epidemiology of demographic surveillance sites cover relatively their be to entire countries or This in to the ALPHA Network study sites, but their from a to data and repeated over of can be study sites are used to or are by medical facilities. of the data from across the ALPHA Network some of the as are more they can be in distinct with and socioeconomic profiles and different fieldwork The ALPHA is to in analyses that the of a pooled include the of HIV-associated mortality and a study on the of HIV during 14 the ALPHA Network data from demographic surveillance sites, it many of their These include high population and and both temporary and population movements with a more the from respondent and survey to a of surveillance sites are the and of and to the ALPHA on the of the data and an of the and data collection and and study protocols often over and data to a standard is both and time is to data and in detail. The of demographic surveillance with health facility data is an and relatively recent of the ALPHA data for but it is a and most of the health facilities in the study sites do not patient and do not have patient In addition, most health facilities are independently managed and the between research and health services has to be with The ALPHA Network data and estimates to the Reference Group on Estimates, Modelling and and the HIV Modelling demographic data from most ALPHA Network member sites are available through [ ]. the ALPHA Network has a to a of the data in a by the of and is to a to the use of data that are not to is at the of participating study site, but data may be through the at the London School of Hygiene and Tropical Medicine including a short of their be to [ ]. information about the ALPHA including a of the are available on the ALPHA Network [ ]. in a The ALPHA Network population-based HIV surveillance sites in and was established in 2005 and aims to strengthen the analytical capacity for HIV research through collaboration and to broaden the evidence base on HIV epidemiology for sites HIV and health services utilization in populations that range from approximately 20 000 to 220 000 These contribute over person-years of exposure and over 000 person-years by people who are to be The ALPHA Network is an for population-level monitoring of the HIV the of and treatment and their effects on individuals and to is at the of of the study sites but may be through the at information about the ALPHA Network and are available on its [ ]. The for the from the and is by the London School of Hygiene and Tropical Medicine its in 2005, the of study sites. The is now in its and has to study sites. has been from the and for monitoring mortality in the of and the for the effects of HIV on and and have ALPHA Network and of interest in and of