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/ About / ACS among PWUD / ACS among people who use drugs (PWUD) Between 1984-2016, a total of 1,680 PWUD were included in the ACS of whom 1,303 had at least two cohort visits (maximum 78 visits). Study enrolment and data collection continued until 2014 and February 2016, respectively. Data and samples from the participants of this cohort are still being used for research. Before 2014, participants visited the GGD Amsterdam every four to six months. They completed a standardised questionnaire designed to obtain information regarding medical history, sexual and drug use behaviour, underlying psychosocial determinants, healthcare use, depression, psychological disorders, and demographics. In addition, participants with HIV, and in the past also HIV-negative participants, underwent a medical examination. Blood was collected for diagnostic tests and storage. In 2014, the cohort was closed for new participants and PWUD included in the ACS were divided into two groups in line with the advice of the international scientific advisory committee in 2013. Group 1 consisted of PWUD who visited the Public Health Service of Amsterdam once a year to complete questionnaires with no testing and blood sampling. Group 2, the focus group, consisted of PWUD who were 1) living with HIV; 2) hepatitis C virus (HCV) seroconverters; 3) multiple-exposed, non-infected with HIV and HCV, and 4) a random control group. This group visited the GGD Amsterdam twice a year for testing and blood sampling and to fill out questionnaires, as in previous years. Regular follow up of drug users continued until February 2016. Finally, all drug users who had ever participated in the ACS were invited for an end-of-study interview. A total of 182 end-of-study interviews were held between February and July 2016, after which the follow up of drug users was successfully ended. Of the 1,680 PWUD, 323 were living with HIV at entry, and 99 acquired HIV during follow up. HIV incidence declined over time and stabilized after 1999 at almost zero new infections per 100 person years. The last HIV seroconversion was seen in 2012. By 31 December 2016, 576 deaths had been confirmed among PWUD. The median age of the PWUD who visited the ACS in 2016 was 55, 8.1% had attained a high level of education, and 63.4% were born in the Netherlands.

Submit your Research Proposal Are you planning a research project? Then, you can submit a research proposal to obtain data or material of participants from the Amsterdam Cohort Studies. Please use the following documents for your proposal: application form A application form B If you are not affiliated with the ACS, please contact Neeltje Kootstra (n.a.kootstra@amsterdamumc.nl ) before submitting your full proposal. If you are affiliated with the ACS, you can send your research proposal to Neeltje Kootstra (n.a.kootstra@amsterdamumc.nl ). The project leaders of ACS decide whether the application will be approved, a process that requires sufficient time. If the proposal is approved, we will make an appointment with you to further arrange the sharing of data or materials. / Researchers / ACS Study Protocol The inclusion criteria for the ACS are as follows: Assigned male sex at birth Having had sex with a man in the preceding 6 months At least 16 years of age Proficient in reading and/or speaking Dutch Living in the Amsterdam region or makes use of MSM-related (virtual) meeting places in Amsterdam Able and willing to provide informed consent After assessing the inclusion criteria and providing written informed consent, MSM enter one of two study arms. Study arm 1: Participants without HIV Study arm 2: Participants living with HIV Study visits to the ACS: 1. Baseline visit. All study participants complete a study-staff assisted questionnaire on key demographic characteristics and medical history. Additionally, participants complete an online questionnaire about other socio-demographic characteristics, health, wellbeing, sexual behavior and associated factors. HIV/STI testing is performed at the Public Health Service of Amsterdam and blood is collected for storage. 2. 6-monthly follow-up visits. Semiannually, all participants receive an online questionnaire about health, wellbeing, sexual behavior, and associated factors. HIV/STI testing is performed at the Public Health Service of Amsterdam and blood is collected for storage. If a participant is newly diagnosed with HIV during follow-up, he is invited for an additional study visit (the seroconversion visit) in which he completes a study staff assisted seroconversion questionnaire and is asked if he wants to keep participating in the ACS. During the first 6 months after the seroconversion visit, the participant visits the cohort every month to draw blood and complete a short health questionnaire. After this period follow-up becomes semiannually again. Guidelines for using ACS data Researchers can submit research proposals to obtain data or material of participants from the ACS. Participants who contributed to the study have given informed consent to conduct research within the scope of the study. This is one of the criteria that is considered when a research proposal is submitted. It is not allowed to use ACS data for other reasons than outlined in the approved research proposal. In addition, you must comply with laws and regulations such as the GDPR. A data or material sharing agreement must be signed in advance. Data Collection and dictionary Participants complete online questionnaires prior to their study visits. During the study visits, additional data are collected and samples are taken for HIV/STI testing, testing for other infections, and storage. Questionnaires and tests have changed and can still change over time. A comprehensive data dictionary for the ACS is currently under development. It will provide an overview and description of the available variables and datasets. In the meantime, researchers with questions about available data are encouraged to contact the ACS research team. ACS for researchers The ACS is a longitudinal study with >40 years of follow-up. The behavioural & psyschosocial data and biomedical material collection is large and offers many opportunities for research. The ACS team is multidisciplinary and enjoys working with scientists all over the world. On this page you will find how to work together with the ACS and we provide information on our study protocol and data collection.

The Amsterdam Cohort Study (ACSresearch.nl) is a prospective observational study initiated in 1984, focusing on HIV/AIDS and other blood-borne and sexually transmitted infections. With over 35 years of multidisciplinary research, the ACS investigates the prevalence, incidence, determinants, and natural course of these infections, contributing significantly to public health knowledge. / The Amsterdam Cohort Studies The Amsterdam Cohort Study (ACS) is a prospective observational cohort study that focusses on HIV/ AIDS and other blood-borne infections, sexually transmittable infections (STI) and other infections. The ACS was initiated in 1984 and has mainly focused on men who have sex with men. Between 1984-2016, the study was expanded to include people who use drugs. Initially focused on HIV/AIDS, the ACS has since expanded to study a broad range of infectious diseases, including hepatitis viruses A, B, and C, chlamydia, gonorrhoeae, human papillomavirus (HPV), herpesviruses, and coronaviruses. From the outset, the ACS has adopted a multidisciplinary approach, examining the prevalence and incidence of infections, their determinants, and their natural history and pathogenesis. The long-term collection of sexual behaviour data is a key strength of the ACS, enabling in-depth analyses of behavioural trends over time. read more » ACS for researchers The ACS is a longitudinal study with >40 years of follow-up. The data and material collection is large and offers many opportunities for research. The ACS team enjoys working with scientists all over the world. On this page you will find how to work together with the ACS and we provide information on our study protocol and data collection. read more » ACS for participants Scientifically, the ACS has been highly successful, largely due to the exceptional commitment of its participants, who visit the study every six months. We are deeply grateful for this long-standing engagement: some participants have been involved for over 40 years. Each year, new participants join while others leave, reflecting the dynamic nature of the cohort. Participation in the ACS is voluntary, and participants may withdraw at any time. The ACS aims to remain a good reflection of the MSM community in Amsterdam. read more » Publications with ACS data The ACS publishes peer-reviewed scientific articles, PhD theses and yearly reports. Since the start of the ACS, more than 300 articles and 50 theses have been published. read more »

Interested in participating? Would you like to participate in the Amsterdam Cohort Study? You can join if you: are at least 18 years old live in Amsterdam or have a tight connection with the city have had at least 1 male sexual partner in the past 6 months provide informed consent Registration form / Participants / ACS for participants Scientifically, the ACS has been highly successful, largely due to the exceptional commitment of its participants, who visit the study every six months. We are deeply grateful for this long-standing engagement: some participants have been involved for over 40 years. Each year, new participants join while others leave, reflecting the dynamic nature of the cohort. Participation in the ACS is voluntary, and participants may withdraw at any time. The ACS aims to remain a good reflection of the MSM community in Amsterdam.

/ About / About the Amsterdam Cohort Studies The Amsterdam Cohort Studies (ACS) on HIV and AIDS started shortly after the first cases of AIDS were diagnosed in the Netherlands. Since October 1984, men who have sex with men (MSM) have been enrolled in this prospective cohort study. A second cohort involving people who use/used (injecting) drugs (PWUD/PWID) was initiated in 1985 and discontinued in 2016. From the onset, research in the ACS has taken a multidisciplinary approach, integrating epidemiology, social science, virology, immunology, and clinical medicine in one study team. This unique collaboration has been highly productive, significantly contributing to the knowledge and understanding of many different aspects of HIV-1 infection, as well as other infections including STI (e.g., chlamydia, gonorrhea, syphilis, viral hepatitis B and C [HBV and HCV] and human papillomavirus [HPV]) and (re-)emerging infectious diseases (COVID-19, mpox). This expertise, in turn, has contributed directly to advances in prevention, diagnosis, and management of these infections. ACS among people who use or inject drugs (PWUD/PWID) Between 1984-2016, a total of 1,680 PWUD were included in the ACS of whom 1,303 had at least two cohort visits (maximum 78 visits). Study enrolment and data collection continued until 2014 and February 2016, respectively. Data and samples from the participants of this cohort are still being used for research. read more » ACS among men who have sex with men (MSM) As of 31 December 2024, 3,024 MSM have been included in the ACS since its initiation. Every three to six months, participants complete a questionnaire on their medical history, sexual behaviour and drug use, mental health, and health care use. Moreover, blood is collected for diagnostic tests and storage at the ACS biobank. read more » Collaborating institutes and funding The ACS is a collaboration between the following institutes: In previous years, Sanquin Blood Supply Foundation, Medical Center Jan van Goyen, and the HIV Focus Center of the DC-Clinics also contributed to sample and data collection, which are still being used in current research projects. In addition, there are numerous collaborations between the ACS and other research groups, both within and outside the Netherlands. The ACS is financially supported by the Centre for Infectious Disease Control Netherlands of the National Institute for Public Health and the Environment (Centrum voor Infectieziektenbestrijding - Rijksinstituut voor Volksgezondheid en Milieu, RIVM-CIb). ACS Project team The ACS team consists of scientists with different backgrounds, PhD students, study nurses, medical doctors and data managers. Data collection takes place at the Public Health Service of Amsterdam (GGD Amsterdam) and additional lab tests are performed at the UMC Amsterdam, location Meibergdreef. The study is directed by the steering committee. The advisory board advices on the scientific direction of the study. read more »

ACS Publications Scientific research conducted with ACS data is published in national and international peer-reviewed scientific journals and in theses written by PhD candidates. Annually, an update of the study is published in the year reports of the Dutch HIV Monitoring Foundation. Year reports » ACS theses & articles HIV monitoring report / Publications /

/ About / ACS among MSM / ACS among men who have sex with men (MSM) As of 31 December 2024, 3,024 MSM have been included in the ACS since its initiation. Every three to six months, participants complete a questionnaire on their medical history, sexual behaviour and drug use, mental health, and health care use. Moreover, blood is collected for diagnostic tests and storage at the ACS biobank. Of the 3,024 MSM, 608 were living with HIV at entry into the study and 267 acquired HIV during follow up. The inclusion criteria for the Amsterdam Cohort Studies (ACS) have evolved over time. In 1984-85, men who had had sexual contact with a man in the preceding six months were eligible, regardless of their HIV status. Between 1985-88, only HIV-negative men of all age groups living in or around Amsterdam with at least two male sexual partners in the preceding six months were eligible to participate. Between 1988-98, the cohort also included MSM with HIV. Between 1995–2004, only men aged 30 years or younger, with at least one male sexual partner in the preceding six months, were eligible. Since 2005, HIV-negative men of all ages have been eligible to participate in the ACS if they live in, or are closely connected to the city of Amsterdam, and have had at least one male sexual partner in the preceding six months. Following recommendations from the International Scientific Advisory Committee in 2013, the cohort continues to actively recruit young HIV-negative MSM (aged 30 years or younger). Participants who acquired HIV during follow-up in the ACS remained in the cohort until 1999, after which follow-up of a subset of MSM with HIV was transferred to the MC Jan van Goyen. In 2003, the HIV Research in Positive Individuals (Hiv Onderzoek onder Positieven, HOP) protocol was initiated. Individuals with a recent HIV acquisition – either at study enrolment or during follow-up - continue to attend study visits at the Public Health Service Amsterdam or at an HIV treatment centre. Blood samples from these participants are stored and behavioural data are collected every six months. Clinical data from these participants are provided by Stichting hiv monitoring. In 2023, 664 participants without HIV and 42 participants with HIV were in follow-up and had had at least one study visit in 2023 or 2024. The median age of active participants was 47 at their last study visit. The majority were born in the Netherlands and were residents of Amsterdam (84% and 79%, respectively). In total, 80% of the participants had a college degree or higher. HIV incidence The observed HIV incidence rate among MSM participating in the ACS has declined over time. In 1985-93, it declined significantly, then stabilised in 1993-96, before rising in 1996-2009. From 2009 onwards, the HIV incidence decreased significantly. Further information on trends in sexual behavior, other infections such as STI and SARS-CoV-2 can be found in the ACS year report which is part of the yearly Monitoring report of Stichting hiv monitoring and in our scientific publications.

The Amsterdam Cohort Study (ACS) is a prospective observational study initiated in 1984, focusing on HIV/AIDS and other blood-borne and sexually transmitted infections. With over 35 years of multidisciplinary research, the ACS investigates the prevalence, incidence, determinants, and natural course of these infections, contributing significantly to public health knowledge. ACS Publications The ACS publishes peer-reviewed scientific articles, theses and year reports. Since the start of the ACS, more than XXX articles and XXX theses have been published. Open-access data is available for educational purposes. read more » De Amsterdamse Cohort Studie De Amsterdam Cohort Study (ACSresearch.nl) onderzoekt hiv/aids en andere door bloed overgedragen infecties (BBI), seksueel overdraagbare infecties (SOA) en andere infecties is een prospectieve observationele cohortstudie. De ACS onder mannen die seks hebben met mannen (MSM) begon in 1984. In 1985 werd de studie uitgebreid met mensen die drugs gebruiken. In de beginfase lag de focus van het onderzoek op hiv/aids. Later werd de studie verbreed en omvatte onderzoek naar hepatitisvirussen A, B en C, Chlamydia, gonorroe, humaan papillomavirus (HPV), herpesvirussen, coronavirussen, enzovoort. Vanaf het begin heeft onderzoek binnen de ACS een multidisciplinaire aanpak gevolgd. De ACS onderzoekt de prevalentie en incidentie van infecties, de bijbehorende determinanten en het natuurlijke verloop en de pathogenese van deze infecties. read more » ACS for researchers The ACS is a longitudinal study with >35 years of follow-up. The data and material collection is large and offers many opportunities for research. The ACS team enjoys working with scientists all over the world. On this page you will find how to work together with the ACS and we provide information on our study protocol and data collection. read more » ACS for participants Scientifically, the ACS is a very successful study. This is due to its highly commitment participants who visit the study every 6 months. We are grateful for their commitment. Some participants have been participating since that start of the study. Every year new people join the study and some participants leave. Participation is voluntary and you can stop at any time. The ACS aims to be a good reflection of the MSM community in Amsterdam. read more » Collaborating Institutes and Funding Within the ACS, different institutes collaborate to bring together data and biological sample collections, and to conduct research. These include: From the start, Sanquin Blood Supply Foundation has been involved in the ACS and, since 2007, has provided financial support for the biobank of viable peripheral blood mononuclear cells (PBMC) at the AMC’s Department of Experimental Immunology. In addition, there are numerous collaborations between the ACS and other research groups, both within and outside the Netherlands. The ACS is financially supported by the Centre for Infectious Disease Control Netherlands of the National Institute for Public Health and the Environment (Centrum voor Infectieziektenbestrijding-Rijksinstituut voor Volksgezondheid en Milieu, RIVM-CIb). Data dictionairy Participants complete online questionnaires prior to their study visits. During the study visits, additional data are collected and samples are taken for HIV/STI testing and storage. Currently, the following questionnaires are used: data dictionairy » Interested in participating? Would you like to contribute to the Amsterdam Cohort Studies by participating in this ongoing study? We are happy to have you join our research group. You can join if you: are at least 18 years old live in Amsterdam or have a tight connection with the city have had at least 1 male sexual partner in the past 6 months and are willing to participate registration form ACS publications The ACS publishes peer-reviewed scientific articles, theses and year reports. Since the start of the ACS, more than XXX articles and XXX theses have been published. Open-access data is available for educational purposes. read more » / Publications / Test Page /

ACS Team members Short text introducing all team members and what tey have in common / dedication to.... Payton Hillman GGD Amsterdam James Wilson Affiliates Jessica Davis Affiliates Chloe Williams Affiliates ACS Advisory board Short text introducing all team members and what tey have in common / dedication to.... Payton Hillman GGD Amsterdam James Wilson Affiliates Jessica Davis Affiliates Chloe Williams Affiliates / ACS People /