Background Social media technologies are newly emerging tools that can be used for HIV prevention and testing in low- and middle-income countries, such as Peru. This study examined the efficacy of using the Harnessing Online Peer Education (HOPE) social media intervention to increase HIV testing among men who have sex with men (MSM) in Peru. Methods In a cluster randomized controlled trial with concealed allocation, Peruvian MSM from Greater Lima/Callao (N = 556) were randomly assigned to join private intervention or control groups on Facebook for 12 weeks. In the intervention condition, forty-nine Peruvian MSM were trained and randomly assigned to be HIV prevention mentors to participants via Facebook groups over 12 weeks. Control participants received an enhanced standard of care, including standard offline HIV prevention available in Peru as well as participation in Facebook groups (without peer leaders) that provided study updates and HIV testing information. After accepting a request to join the groups, continued participation was voluntary. Participants could request a free HIV test at a local community clinic, and completed questionnaires on HIV risk behaviors and social media use at baseline and 12-week follow-up. Findings Between March 19, 2012, and June 11, 2012, and Sept 26, 2012, and Dec 19, 2012, 556 participants were randomly assigned to intervention groups (N=278) or control groups (N=278); we analyse data for 252 and 246. 43 participants (17%) in the intervention group and 16 (7%) in the control groups got tested for HIV (adjusted odds ratio 2.61, 95% CI 1.55–4.38). No adverse events were reported. Retention at 12-week follow-up was 90%. Across conditions, 7 (87.5%) of the 8 participants who tested positive were linked to care at a local clinic. Interpretation Development of peer-mentored social media communities seemed to be an effective method to increase HIV testing among high-risk populations in Peru.: Results suggest that the HOPE social media HIV intervention may improve HIV testing rates among MSM in Peru. Funding National Institute of Mental Health (NIMH MH090844)

We reviewed the use of agent-based modeling (ABM), a systems science method, in understanding noncommunicable diseases (NCDs) and their public health risk factors. We systematically reviewed studies in PubMed, ScienceDirect, and Web of Sciences published from January 2003 to July 2014. We retrieved 22 relevant articles; each had an observational or interventional design. Physical activity and diet were the most-studied outcomes. Often, single agent types were modeled, and the environment was usually irrelevant to the studied outcome. Predictive validation and sensitivity analyses were most used to validate models. Although increasingly used to study NCDs, ABM remains underutilized and, where used, is suboptimally reported in public health studies. Its use in studying NCDs will benefit from clarified best practices and improved rigor to establish its usefulness and facilitate replication, interpretation, and application.