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.