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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, we share our study protocol, information on our data collection, and recent questionnaires. We also explain how to submit a research proposal to collaborate with the ACS and obtain data. 

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:

If you are affiliated with the ACS, you can send your research proposal to Neeltje Kootstra ( You will receive a receipt within 3 days. 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.

If you are not affiliated with the ACS, please contact Neeltje Kootstra ( before submitting your full proposal. 

data request form »
material request form »

ACS Study Protocol

Inclusion criteria:

  • Being male

  • Having had sex with a men in the preceding 6 months

  • Being at least 16 years of age

  • Proficient in reading/speaking Dutch/English

  • Living in the Amsterdam area or being involved in MSM-related activities taking place in Amsterdam

  • Provide written informed consent
    Study arm specific inclusion criteria:

  • HIV-negative, confirmed by the HIV test performed at the baseline visit [Study arm 1 & 2]

  • Not using PrEP or being in PrEP-care elsewhere [Study arm 1]

  • Using PrEP or initiate PrEP use at baseline and PrEP-care provided by research personnel of the cohort [Study arm 2]

  • HIV-1-positive at baseline [Study arm 3]

  • HIV-1 seroconversion during a follow-up [Study arm 4]

After assessing the inclusion criteria and providing written informed consent, the participant enters ACS study arm 1, 2 or 3. 


Study arm 1: Participants are HIV-negative and are not using PrEP or they receive PrEP-care elsewhere.

Study arm 2: Participants are HIV-negative, they are using PrEP and receive PrEP-care at the GGD Amsterdam.
Study arm 3: Participants are HIV-positive.


Study visits:

Baseline visit. All study participants complete a study staff assisted report form about 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 tests are performed and blood is collected for storage.


6-monthly follow-up visits. Semiannually, all participants receive an online questionnaire about health, wellbeing, sexual behavior and associated factors. HIV/STI tests are performed and blood is collected for storage.


3-monthly in-between study visits. Participants in study arm 2 have 2 extra in-between visits for PrEP-care. HIV/STI tests are performed. Prior to this visit, participants complete a short health questionnaire. HIV-positive participants in study arm 3 are given the opportunity to be tested for STI every 3 months. If they prefer 3-monthly visits, they also complete the additional health questionnaire.


Study arm 4: Participants are newly diagnosed with HIV during follow-up.  

The participant is invited for an extra study visit (the seroconversion visit) in which he completes the study staff assisted seroconversion report form and is asked to participate in study arm 4. During the first 6 months after the seroconversion visit, participants visit the cohort every month to draw blood and complete a short health questionnaire. After this period follow-up becomes comparable to study arm 3.

Guidelines for using ACS data

The ACS collects data from study participants. They 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 data for other reasons than 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

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:

Questionnare 01
Questionnare 02
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