International Journal of Drug Policy - 2014

Volume 25 Issue 3 May 2014

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K.N. Deering et al. / International Journal of Drug Policy 25 (2014) 533–542 535 transgender inclusive). Interviews were conducted in places where women felt comfortable (i.e., three office site locations across Vancouver; within indoor sex work venues). As executed previ- ously, outdoor sex work 'strolls' and indoor venues were identified through a participatory mapping exercise conducted with cur- rent/former SWs (Shannon et al., 2007), and continuously updated by the outreach team. The study holds ethical approval through Providence Health Care/University of British Columbia Research Ethics Board. All participants receive an honorarium of $40CAD at each bi-annual visit for their time, expertise and travel. Questionnaires and measures Following informed consent, at baseline and each semi-annual follow-up visit, participants completed questionnaires by trained interviewers (both SW and non-SW interviewers) that elicited responses relating to socio-demographics, sex work patterns/client experiences, work environments, occupational violence and inter- actions with policing, characteristics of non-commercial or regular partnerships, violence and trauma, and drug use. Participants also completed a nurse-administered questionnaire that elicited responses relating to overall physical, mental and emotional health, sexual and reproductive health and HIV testing and treatment. As part of the nursing visit, SWs were also provided with extensive pre/and post-test counselling, testing for HIV, Hepatitis C Virus and sexually transmitted infections (STIs), and referral for care and support services. Treatment was provided for symptomatic STI infections by an on-site nurse, and free serology and Papanicolaou testing were also available for those in need, regardless of study enrollment. Study sample Our study sample included SWs who solicited for or serviced clients primarily in street-based/outdoor settings. We considered only baseline data. Outcomes Based on a priori interest in examining overlapping drug use and sexual risks, we included two sexual risk outcomes in this analysis, measured in the last six months: (1) exchanged sexual services directed for drugs ('yes' = always, usually, sometimes, occa- sionally; versus 'no' = never); and (2) exchanged sexual services while high ('yes' = always, usually, sometimes, occasionally; versus 'no' = never). Potential confounders We considered the following potential confounders as mea- sured once at baseline: age; reporting being a sexual minority (lesbian, gay, bisexual, transgender, transsexual, two-spirit versus heterosexual and non-transgender); Indigenous/Aboriginal ances- try (including First Nations and Métis, Inuit status); migrant/new immigrant status (born outside Canada); and age at first sex work; as well as time-varying confounders updated in the last six months: homeless; had a manager; non-injection drug use; injection drug use; and numbers of clients per week; and expe- rienced police harassment without arrest (i.e., told to move on, threatened with arrest/detainment/fine, searched, followed, picked up and driven elsewhere to work, verbally harassed, detained, delayed/held against will without arrest, physically assaulted, drugs/drug use equipment taken, other property taken, proposi- tioned to exchange sex, coerced into providing sexual favours). Selection of built environment indicators We used conceptual and analytic methods in the exploratory development of a 'spatial isolation index' within street- based/outdoor sex work environments, using seven variables measuring different aspects of the built environment (Table 1). In the current study, the 'spatial isolation index' and the term 'spatial isolation' in general are intended to reflect how sex work in our setting has been geographically concentrated in more hidden and isolated spaces, away from the public eye (e.g., busy streets, residential areas) – research has suggested that these spaces are moreover often further away from health resources (e.g., harm reduction and safer sex equipment) and safety resources (e.g., groups of people, other SWs, drop-in spaces, street-lights/busier commercial settings) (Shannon, Kerr, Allinott, et al., 2008; Shannon et al., 2009). To derive the seven individual built environment indi- cators for use in development of an index, we used a combination of AESHA survey data and seven variables measuring features of the built environment collected from publicly available data from the City of Vancouver ("City of Vancouver Open Data Catalogue," 2013) and DTMI Spatial ("DMTI Spatial Data and Services," 2013). Little research is available on community-level indicators of built environment and their relationships with health harms to street- based SWs. As this study was exploratory in nature, we developed indicators that were suggested by research to be important in shaping risk environments to SWs in street-based/outdoor settings (Shannon, Kerr, Allinott, et al., 2008; Shannon, Rusch, et al., 2008). From the AESHA data, we used two variables measuring key spatial aspects of SWs' work environments in the development of these indicators: locations of SWs' main places of solicitation and main places where services were provided to clients, in the last six months. Locations were provided by participants in the form of addresses or cross-streets and geocoded (i.e., assigned latitude and longitude). Using ArcGIS 10.1 ("ArcGIS Desktop," 2011), around each location, spatial buffers were created. Effectively, 'buffers' are equivalent to a circle drawn around each location as provided by participants. Each circle had an assigned radius of 50 m, as we were interested in assessing the effects of built environment within a relatively near proximity to primary sex work environments. These effects were perceived to be likely to have the largest effect on SWs' HIV risk. In line with previous work by our team (Rusch et al., 2010; Shannon, Rusch, et al., 2008), confidentiality of participants' individual responses was ensured as only aggregate measures of sex work spaces were used in analysis. Neighbourhood environment variables drawn from four different groups of external/publicly available data were further used in the development of the index: road, lighting, building footprint and land use ("City of Vancouver Open Data Catalogue," 2013; "DMTI Spatial Data and Services," 2013). These variables included, within each buffer, the: (1) sum of the length of major roads; (2) sum of the length of alley roads; (3) percentage of commercial land use; (4) percentage of industrial land use; (5) percentage of parks; (6) number of light posts; and (7) percentage of the building footprint, or total built environment (i.e., coverage of land by commercial buildings) (Table 1 and Fig. 1). Development of an index for 50 m buffer We drew on other studies that have developed indices of the built environment using multiple indicators of the built environ- ment (e.g., neighbourhood disorder; street speed limits, volume of cars, and street connectivity, walkability, land use, dwelling den- sity) (Badland et al., 2009; Cohen et al., 2000; Kroeger, Messer, Edwards, & Miranda, 2012; McGinn, Evenson, Herring, Huston, & Rodriguez, 2007).

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