Editors' Summary Background Intimate partner violence (IPV, also called domestic violence) is a common and widespread problem. Globally, nearly a third of women are affected by IPV at some time in their life, but the prevalence of IPV (the proportion of the population affected by IPV) varies widely between countries. In central sub-Saharan Africa, for example, nearly two-thirds of women experience IPV during their lifetime, whereas in East Asia only one-sixth of women are affected. IPV is defined as physical, sexual, or emotional harm that is perpetrated on an individual by a current or former partner or spouse. Physical violence includes hitting, kicking, and other types of physical force; sexual violence means forcing a partner to take part in a sex act when the partner does not consent; and emotional abuse includes threatening a partner by, for example, stalking them or preventing them from seeing their family. The adverse effects of IPV for women include physical injury, depression and suicidal behaviour, and sexual and reproductive health problems such as HIV infection and unwanted pregnancies. Why Was This Study Done? ? IPV affects men as well as women. Men can be subjected to IPV either by a female partner or by a male partner in the case of men who have sex with men (MSM, a term that encompasses homosexual, bisexual, and transgender men, and heterosexual men who sometimes have sex with men). Recent reviews suggest that the prevalence of IPV in same-sex couples is as high as the prevalence of IPV for women in opposite-sex relationships: reported lifetime prevalences of IPV in homosexual male relationships range between 15.4% and 51%. Little is known, however, about the adverse health effects of IPV on MSM. It is important to understand how IPV affects the health of MSM so that appropriate services and interventions can be provided to support MSM who experience IPV. In this systematic review (a study that identifies all the research on a given topic using predefined criteria) and meta-analysis (a study that combines the results of several studies using statistical methods), the researchers investigate the associations between the experience and perpetration of IPV and various health conditions and sexual risk behaviours among MSM. What Did the Researchers Do and Find? ? The researchers identified 19 studies that investigated associations between IPV and various health conditions or sexual risk behaviours (for example, unprotected anal sex, a risk factor for HIV infection) among MSM. The associations were expressed as odds ratios (ORs); an OR represents the odds (chances) that an outcome will occur given a particular exposure, compared to the odds of the outcome occurring in the absence of that exposure. The researchers estimated pooled ORs from the data in the individual studies using meta-analysis. The pooled lifetime prevalence of experiencing any IPV (which was measured in six studies) was 48%. Exposure to IPV as a victim was associated with an increased risk of substance (alcohol or drug) use (OR = 1.88, data from nine studies), reporting depressive symptoms (OR = 1.52, data from three studies), being HIV positive (OR = 1.46, data from ten studies), and engagement in unprotected sex (OR = 1.72, data from eight studies). Perpetration of IPV was associated with an increased risk of substance abuse (OR = 1.99, data from six studies). What Do These Findings Mean? ? These findings suggest that MSM frequently experience IPV and that exposure to IPV is associated with several adverse health conditions and sexual risk behaviours. There were insufficient data to estimate the lifetime prevalence of IPV perpetration among MSM, but these findings also reveal an association between IPV perpetration and substance use. The accuracy of these findings is limited by heterogeneity (variability) between the studies included in the meta-analyses, by the design of these studies, and by the small number of studies. Despite these and other limitations, these findings highlight the need to undertake research to identify interventions to prevent IPV among MSM and to learn more about the health effects of IPV among MSM. They highlight the importance of health care professionals being aware that IPV is a problem for MSM and of training these professionals to assess MSM for IPV. Finally, these results highlight the need to improve the availability and effectiveness of support services to which health care professionals can refer MSM experiencing or perpetrating IPV. Additional Information Please access these websites via the online version of this summary at http://dx.doi.org/10.1371/journal.pmed.1001609. The World Health Organization provides detailed information on intimate partner violence The US Centers for Disease Control and Prevention provides information about IPV and a fact sheet on understanding IPV that includes links to further resources The UK National Health Service Choices website has a webpage about domestic violence, which includes descriptions of personal experiences The US National Domestic Violence Hotline provides confidential help and support to people experiencing IPV, including MSM; its website includes personal stories of IPV The US Gay Men's Domestic Violence Project/GLBTQ Domestic Violence Project provides support and services to MSM experiencing IPV; its website includes some personal stories The UK not-for-profit organization Respect runs two advice lines: the <ext-link ext-link-type="uri" xlink:href="http://www.mensadviceline.org. uk/" xlink:type="simple">Men's Advice Line provides advice and support for men experiencing domestic violence and abuse and the Respect Phoneline provides advice for domestic violence perpetrators and for professionals who would like further information about services for those using violence/abuse in their intimate partner relationships The UK not-for-profit organization ManKind Initiative also provides support for male victims of IPV The UK not-for-profit organization Broken Rainbow UK provides help and support for lesbians and MSM experiencing IPV MedlinePlus provides links to other resources about domestic violence (in English and Spanish) The UK charity Galop gives advice and support to people who have experienced biphobia, homophobia, transphobia, sexual violence, or domestic abuse Background Intimate partner violence (IPV) among men who have sex with men (MSM) is a significant problem. Little is known about the association between IPV and health for MSM. We aimed to estimate the association between experience and perpetration of IPV, and various health conditions and sexual risk behaviours among MSM. Methods and Findings We searched 13 electronic databases up to 23 October 2013 to identify research studies reporting the odds of health conditions or sexual risk behaviours for MSM experiencing or perpetrating IPV. Nineteen studies with 13,797 participants were included in the review. Random effects meta-analyses were performed to estimate pooled odds ratios (ORs). Exposure to IPV as a victim was associated with increased odds of substance use (OR = 1.88, 95% CIOR 1.59-2.22, I-2 = 46.9%, 95% CII2 0%-78%), being HIV positive (OR = 1.46, 95% CIOR 1.26-1.69, I-2 = 0.0%, 95% CII2 0%-62%), reporting depressive symptoms (OR = 1.52, 95% CIOR 1.24-1.86, I-2 = 9.9%, 95% CII2 0%-91%), and engagement in unprotected anal sex (OR = 1.72, 95% CIOR 1.44-2.05, I-2 = 0.0%, 95% CII2 0%-68%). Perpetration of IPV was associated with increased odds of substance use (OR = 1.99, 95% CIOR 1.33-2.99, I-2 = 73.1%). These results should be interpreted with caution because of methodological weaknesses such as the lack of validated tools to measure IPV in this population and the diversity of recall periods and key outcomes in the identified studies. Conclusions MSM who are victims of IPV are more likely to engage in substance use, suffer from depressive symptoms, be HIV positive, and engage in unprotected anal sex. MSM who perpetrate IPV are more likely to engage in substance use. Our results highlight the need for research into effective interventions to prevent IPV in MSM, as well as the importance of providing health care professionals with training in how to address issues of IPV among MSM and the need to raise awareness of local and national support services. Please see later in the article for the Editors' Summary
