Sexualised drug use and chemsex in Italy: A questionnaire study based on a cohort of clients attending a STI outpatient service in Milan

Background: Chemsex is a heterogeneous phenomenon with differences in distribution, setting, motivations and type of substances consumed between countries. The lack of data at national level of the Italian situation creates a perception of reduced need for intervention. Methods: Anonymous paper questionnaires were distributed to patients who had registered themselves at the STI Department IRCCS Ca' Granda Policlinico in Milan. Results: A significant association was demonstrated between use of sexualised drugs, chemsex and the following variables: (1). Number of partners: in the group of clients with more than five partners, sexualised drug users were more than twice compared with those in the group with less than five partners (35.2% vs 16.2%) p<0.0001. (2). Use of dating apps: more than one out of two persons who used drugs during sex affirmed looking for partners on internet, p = 0.0059. (3). Low condom uses with occasional partners: percentage of individuals who declared not to use condoms or devices during their sexual encounters with occasional partners is more than twice as high in the sexualised drug users group with respect to controls (44.6% vs 21.4%); p = 0.0006). (4). Use of post exposure prophylaxis (PEP): among the PEP users, more than half participants belonged to the sexualised drug users' group; p = 0.0021. Conclusions: Sexualised drug use and chemsex are frequently practiced in Milan. This survey identified a specific population with higher-risk sexual behaviours and increased incidence of acute bacterial STIs.