Ti et al. BMC Public Health 2012, 12:189 http://www.biomedcentral.com/1471-2458/12/189 positive test result, HIV-related stigma, and the resulting impacts on relationships with family and public authori- ties are among the reasons why IDU do not get tested for HIV [8,9]. In Thailand, where the prevalence of HIV among IDU is as high as 50% [10], an excessive focus on drug law enforcement has likely contributed to the suboptimal coverage of HIV prevention, treatment and care among this population [11,12]. For example, some public hospitals reportedly collect and share information concerning patients’ drug use behaviour with police in Thailand [11]. This compromising of patient confidenti- ality prevents many IDU from wanting to use govern- ment testing services, especially given that, in order to qualify for a free HIV test at public testing clinics, IDU must declare their risk behaviour (P. Sririrund, personal communication, April 30, 2011). In addition, if IDU were to get HIV testing at private clinics, there would be the burden of the cost of an HIV test imposed upon them. Collectively, these barriers could potentially undermine access to HIV testing among this population. Recent studies have found that uptake of HIV testing among IDU in parts of Asia is as low as 20% annually [13]. Several studies have shown that peer-based interven- tions for drug users can often extend the reach and effectiveness of conventional public health programs [14,15], especially in settings where drug use is heavily penalized, as in Thailand [16]. There has been increas- ing interest in novel, low-threshold methods of HIV testing, including peer-based testing [17,18]. However, there are currently no peer-based models of HIV testing in Thailand, and concerns have been expressed regard- ing the inadequate voluntary counselling and HIV test- ing services offered to IDU in this setting [11]. Given that knowledge of HIV-positive serostatus can reduce the health burden associated with HIV/AIDS among IDU, and HIV testing and counselling continue to be supported by international health organizations globally [19,20], the lack of these services in Thailand has prompted calls for increased voluntary counselling, test- ing and information services across the country [11]. According to the Reference Group to the United Nations on HIV and Injecting Drug Use, there are an estimated 160,000 IDU living in Thailand [2], of whom the majority are male and between the ages of 30-40 years [16,21]. While there exists some evidence indicat- ing why individuals engaging in illicit drug use have low uptake of HIV testing services [21], little is known about the factors that influence HIV testing among IDU in Thailand. Therefore, we sought to investigate the preva- lence and correlates of HIV testing behaviour among a community-recruited sample of IDU in Bangkok, Thai- land. As well, given the growing interest in low-thresh- old and peer-based HIV testing programs, we also Page 2 of 9 sought to assess willingness to get tested for HIV at a drug-user-run drop-in centre in Bangkok. Methods The Mitsampan Community Research Project (MSCRP) is a collaborative research project involving the Mitsam- pan Harm Reduction Centre (Bangkok, Thailand), the Thai AIDS Treatment Action Group (Bangkok, Thai- land), Chulalongkorn University (Bangkok, Thailand) and the British Columbia Centre for Excellence in HIV/ AIDS (Vancouver, Canada). During June and July of 2009, the research partners undertook a cross-sectional study involving 317 community-recruited IDU. Potential participants were recruited through peer-based outreach efforts and word of mouth. Study participants were then invited to attend the MSHRC to participate in the study. All participants provided informed consent and com- pleted an interviewer-administered questionnaire elicit- ing information about demographic characteristics, drug use, HIV risk behaviour, criminal justice system expo- sure, and experiences with health care. All participants were given 350 baht (approximately US$11) upon com- pletion of the questionnaire. The study has been approved by the research ethics boards of the University of British Columbia and Chulalongkorn University. For the present analyses, we restricted the study sam- ple to individuals who were HIV-negative or of unknown HIV serostatus. As a first step, we compared IDU who had and had not been tested for HIV in the past six months using the Pearson c2 test and Fisher’s exact test (when one or more cells contained values less than or equal to five). Among the participants who had not been tested for HIV in the past six months, we examined the prevalence of ongoing HIV risk behaviour and asked them to indicate reasons why they had not been tested. Second, we compared IDU who were and were not willing to get free HIV testing at MSHRC, again using the Pearson c2 test and Fisher’s exact test (when one or more cells contained values less than or equal to five). The “willingness to get free HIV testing at MSHRC” variable referred to whether participants would get tested at least once at the peer-run drop-in centre. Specifically, we asked: “If the MSHRC offered free HIV testing with pre- and post-counselling (includ- ing referrals to clinics/hospitals), would you take the test?” We then built a multivariate logistic regression model to identify independent predictors of willingness to get free HIV testing at MSHRC by including all vari- ables that were associated with the outcome at the p ≤ 0.10 level in bivariate analyses. Variables considered in both initial bivariate analyses included: gender, median age, relationship status (mar- ried/common law, regular partner vs. separated, dating, single), education level (≥ secondary school vs.