IMPLEMENTATION AND OPERATIONAL RESEARCH:EPIDEMIOLOGY AND PREVENTION Computer-Assisted Intervention for Safer Sex in HIV-Positive Men Having Sex With Men: Findings of a European Randomized Multi-Center Trial Christiana Nöstlinger, PhD,* Tom Platteau, MSc,† Johannes Bogner, PhD, MD,‡ Jozefien Buyze, PhD,† Joanna Dec-Pietrowska, PhD,§ Sonia Dias, PhD,k John Newbury-Helps, PhD,¶ Agnes Kocsis, PhD,¶ Matthias Mueller, MD,‡# Daniela Rojas, PhD,** Danica Stanekova, MD,†† Jacques van Lankveld, PhD,‡‡ and Robert Colebunders, MD, PhD,†§§ the Eurosupport Study Group Objective: Men who have sex with men (MSM) are the key population most affected by HIV in Europe. We performed the first European multicenter, simple-randomized parallel-group study to test the effectiveness of a theory-guided computer-assisted intervention to improve safer sex among HIV-positive men who have sex with men. Methods: Between February, 2011 and February, 2013, 112 participants were enrolled in 8 different European HIV-care settings. Intervention participants received 3 individual counseling sessions facilitated by trained service providers using computer-assisted tools. The control-group received sexual health advice delivered as part of regular HIV care. Outcome behavior (self-reported condom use at last intercourse; combined HIV transmission risk score), its influ- encing factors, and mediating variables were assessed at baseline, and at 3 and 6 months follow-up. Mixed effects models were used to compare primary outcomes (condom use at last intercourse, HIV transmission risk score), and mediation analysis to explore intervention effects. Results: Condom use at last intercourse increased more among intervention than control participants at 3 months follow-up (odds ratio of 3.83; P = 0.03), but not significantly at 6 months follow-up. Intervention participants reported a lower transmission risk at 3 months follow-up than controls (odds ratio compared with baseline of 11.53 and 1.28, respectively; P = 0.008), but this effect became nonsignificant at 6 months. Intervention effects were mediated by the proximal variables, self-efficacy to negotiate condom use and condom attitudes. Conclusions: This intervention showed short-term effectiveness. The intervention should be replicated in other settings, eventually investigating if booster-counseling sessions would yield a longer lasting effect. Key Words: HIV, safer sex, theory-based intervention, condom use, men having sex with men, behavioral counseling (J Acquir Immune Defic Syndr 2016;71:e63–e72) INTRODUCTION HIV infection is a major public health concern in Europe. In 2013, 30 countries in the European Union/ European Economic Area (including European Union Mem- ber States, Norway, Iceland, and Liechtenstein) reported 29,157 new HIV cases. Of those, 42% were reported among men having sex with men (MSM), accounting for the majority of new HIV cases with unprotected sex between men as the predominant HIV transmission mode. 1 Among MSM living with HIV, growing numbers of other sexually transmitted infections (STI) such as gonorrhea and syphilis have also been observed, attributed to condom less sex. 2–4 Several European studies reported such evidence. For instance, Received for publication May 14, 2015; accepted October 14, 2015. From the Departments of *Public Health; †Clinical Sciences, Institute of Tropical Medicine, ITM’s HIV AIDS Center (IHAC), Antwerp, Belgium; ‡Department of Infectious Diseases, Ludwig-Maximilian University, Uni- versity Hospital Munich, Munich, Germany; §Faculty of Education, Sociology, and Health Services, University of Zielona Gora, Zielona Gora, Poland; kInstitute of Tropical Medicine and Hygiene, Lisbon, Portugal; ¶Central North West London NHS Trust, London, United Kingdom; #Department of Medicine, Center for Infectious Diseases and Travel Medicine and IFB Center for Chronic Immunodeficiency, University Medical Center Freiburg, Freiburg, Germany; **AIDES, Mission Innovation Recherche Expérimentation (MIRE), Paris, France; ††National Reference Centre for HIV/AIDS Prevention, Slovak Medical University, Bratislava, Slovak Republic; ‡‡Faculty of Psychology and Educational Sciences, Open University, Heerlen, the Netherlands; and §§Department of Epidemiology and Social Medicine, University of Antwerp, Antwerp, Belgium. Presented in part at the 20th International AIDS Conference, July 20–25, 2014, Melbourne, Australia. Abstract nr. A-641-0366-05126. The Eurosupport study group received funding from the European Union’s Public Health Programme 2008–2013, grant nr. 2008 1204. Additional funding was received through unconditional grants from Gilead, Abbott and Merck. M. Mueller received a grant from MSD Sharp & Dohme GmbH, Germany. The remaining authors have no funding or conflicts of interest to disclose. Supplemental digital content is available for this article. Direct URL citations appear in the printed text and are provided in the HTML and PDF versions of this article on the journal’s Web site (www.jaids.com). “This presentation reflects solely the authors’ view. The European Commis- sion is not liable for any use that may be made of the information provided herein.” Eurosupport 6 was financially supported by the European Commission, grant agreement nr. 2008 1204. Other sponsors were Gilead, Abbott, and Merck. Correspondence to: Christiana Nöstlinger, PhD, Department of Public Health, Institute of Tropical Medicine, Nationalestraat 155, B-2000 Antwerp, Belgium (e-mail: cnoestlinger@itg.be). Copyright © 2015 Wolters Kluwer Health, Inc. All rights reserved. J Acquir Immune Defic Syndr  Volume 71, Number 3, March 1, 2016 www.jaids.com | e63 Copyright © 201 Wolters Kluwer Health, Inc. Unauthorized reproduction of this article is prohibited. 5