title: COBA-Cohort: a prospective cohort of HIV-negative men who have sex with men, attending community-based HIV testing services in five European countries (a study protocol).
abstract: Community-based voluntary counselling and testing (CBVCT) services for men who have sex with men (MSM) can reach those most-at-risk and provide an environment for gay men that is likely to be non-stigmatising. Longitudinal data on the behaviour of HIV-negative MSM are scarce in Europe. The aim of this protocol, developed during the Euro HIV Early Diagnosis And Treatment (EDAT) project, is to implement a multicentre community-based cohort of HIV-negative MSM attending 15 CBVCT services in 5 European countries.
  
  
  
  (1) To describe the patterns of CBVCT use, (2) to estimate HIV incidence, and to identify determinants of (3) HIV seroconversion and (4) HIV and/or sexually transmitted infection (STI) test-seeking behaviour.
  
  
  
  All MSM aged 18 years or over and who had a negative HIV test result are invited to participate in the COmmunity-BAsed Cohort (COBA-Cohort). Study enrolment started in February 2015, and is due to continue for at least 12 months at each study site. Follow-up frequency depends on the testing recommendations in each country (at least 1 test per year). Sociodemographic data are collected at baseline; baseline and follow-up questionnaires both gather data on attitudes and perceptions, discrimination, HIV/STI testing history, sexual behaviour, condom use, and pre- and post-exposure prophylaxis. Descriptive, exploratory and multivariate analyses will be performed to address the main research objectives of this study, using appropriate statistical tests and models. These analyses will be performed on the whole cohort data and stratified by study site or country.
  
  
  
  The study was approved by the Public Health authorities of each country where the study is being implemented. Findings from the COBA-Cohort study will be summarised in a report to the European Commission, and in leaflets to be distributed to study participants. Articles and conference abstracts will be submitted to peer-reviewed journals and conferences.
authors.affiliation: Centre for Epidemiological Studies on HIV/STI of Catalonia (CEEISCAT), Agència de Salut Pública de Catalunya (ASPC), Generalitat de Catalunya, Badalona, Spain The Institute for Health Science Research Germans Trias i Pujol (IGTP), Badalona, Spain.
authors.forename: Nicolas
authors.identifier: 0000-0002-5320-1493
authors.initials: N
authors.lastname: Lorente
authors.affiliation: Centre for Epidemiological Studies on HIV/STI of Catalonia (CEEISCAT), Agència de Salut Pública de Catalunya (ASPC), Generalitat de Catalunya, Badalona, Spain The Institute for Health Science Research Germans Trias i Pujol (IGTP), Badalona, Spain CIBER Epidemiología y Salud Pública (CIBERESP), Madrid, Spain.
authors.forename: Laura
authors.initials: L
authors.lastname: Fernàndez-López
authors.affiliation: GAT-Grupo de Ativistas em Tratamentos, Lisbon, Portugal.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Fuertes
authors.affiliation: AIDES (MIRE-Mission Innovation Recherche Expérimentation), Pantin, France Groupe de Recherche en Psychologie Sociale (GRePS) EA4163, Université de Lyon 2, Bron, France.
authors.forename: Daniela
authors.initials: D
authors.lastname: Rojas Castro
authors.affiliation: AIDS-Fondet, Copenhagen, Denmark.
authors.forename: François
authors.initials: F
authors.lastname: Pichon
authors.affiliation: Legebitra, Ljubljana, Slovenia.
authors.forename: Bojan
authors.initials: B
authors.lastname: Cigan
authors.affiliation: Ath Checkpoint, Athens, Greece.
authors.forename: Sophocles
authors.initials: S
authors.lastname: Chanos
authors.affiliation: EPIUnit, Institute of Public Health, University of Porto, Porto, Portugal.
authors.forename: Paula
authors.initials: P
authors.lastname: Meireles
authors.affiliation: EPIUnit, Institute of Public Health, University of Porto, Porto, Portugal Department of Clinical Epidemiology, Predictive Medicine and Public Health, University of Porto Medical School, Porto, Portugal.
authors.forename: Raquel
authors.identifier: 0000-0002-4408-8134
authors.initials: R
authors.lastname: Lucas
authors.affiliation: AIDES (MIRE-Mission Innovation Recherche Expérimentation), Pantin, France.
authors.forename: Stéphane
authors.initials: S
authors.lastname: Morel
authors.affiliation: AIDS-Fondet, Copenhagen, Denmark.
authors.forename: Per
authors.initials: P
authors.lastname: Slaaen Kaye
authors.affiliation: Centre for Epidemiological Studies on HIV/STI of Catalonia (CEEISCAT), Agència de Salut Pública de Catalunya (ASPC), Generalitat de Catalunya, Badalona, Spain The Institute for Health Science Research Germans Trias i Pujol (IGTP), Badalona, Spain CIBER Epidemiología y Salud Pública (CIBERESP), Madrid, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Agustí
authors.affiliation: National Institute of Public Health, Ljubljana, Slovenia.
authors.forename: Irena
authors.initials: I
authors.lastname: Klavs
authors.affiliation: Institute of Tropical Medicine, Antwerp, Belgium.
authors.forename: Tom
authors.identifier: 0000-0002-5906-4530
authors.initials: T
authors.lastname: Platteau
authors.affiliation: Centre for Epidemiological Studies on HIV/STI of Catalonia (CEEISCAT), Agència de Salut Pública de Catalunya (ASPC), Generalitat de Catalunya, Badalona, Spain The Institute for Health Science Research Germans Trias i Pujol (IGTP), Badalona, Spain CIBER Epidemiología y Salud Pública (CIBERESP), Madrid, Spain Department of Paediatrics, Obstetrics and Gynaecology, and Preventive Medicine, Univ Autonoma Barcelona, Badalona, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Casabona
mesh_terms: D000293:Adolescent; D000328:Adult; D003153:Community Health Services / Q000706:statistics & numerical data*; D003376:Counseling; D005060:Europe / Q000453:epidemiology; D015658:HIV Infections / Q000175:diagnosis / Q000453:epidemiology / Q000635:transmission; D018451:Homosexuality, Male; D006801:Humans; D015994:Incidence; D008297:Male; D008403:Mass Screening; D008875:Middle Aged; D010342:Patient Acceptance of Health Care; D011446:Prospective Studies; D012107:Research Design; D012307:Risk Factors; D012725:Sexual Behavior; D000072339:Sexual and Gender Minorities; D012749:Sexually Transmitted Diseases; D057545:Social Stigma; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: Community-based HIV testing; HIV incidence; HIV-negative cohort; Men who have sex with men; Sexual behaviour