title: Piloting a 'spatial isolation' index: the built environment and sexual and drug use risks to sex workers.
abstract: BACKGROUND
  Employing innovative mapping and spatial analyses of individual and neighbourhood environment data, we examined the social, physical and structural features of overlapping street-based sex work and drug scenes and explored the utility of a 'spatial isolation index' in explaining exchanging sex for drugs and exchanging sex while high.
  
  
  METHODS
  Analyses drew on baseline interview and geographic data (January 2010-October 2011) from a large prospective cohort of street and off-street sex workers (SWs) in Metropolitan Vancouver and external publically-available, neighbourhood environment data. An index measuring 'spatial isolation' was developed from seven indicators measuring features of the built environment within 50m buffers (e.g., industrial or commercial zoning, lighting) surrounding sex work environments. Bivariate and multivariable logistic regression was used to examine associations between the two outcomes (exchanged sex for drugs; exchanged sex while high) and the index, as well as each individual indicator.
  
  
  RESULTS
  Of 510 SWs, 328 worked in street-based/outdoor environments (e.g., streets, parks, alleys) and were included in the analyses. In multivariable analysis, increased spatial isolation surrounding street-based/outdoor SWs' main places of servicing clients as measured with the index was significantly associated with exchanging sex for drugs. Exchanging sex for drugs was also significantly positively associated with an indicator of the built environment suggesting greater spatial isolation (increased percent of parks) and negatively associated with those suggesting decreased spatial isolation (increased percent commercial areas, increased count of lighting, increased building footprint). Exchanging sex while high was negatively associated with increased percent of commercial zones but this association was removed when adjusting for police harassment.
  
  
  CONCLUSIONS
  The results from our exploratory study highlight how built environment shapes risks within overlapping street-based sex work and drug scenes through the development of a novel index comprised of multiple indicators of the built environment available through publicly available data, This study informs the important role that spatially-oriented responses, such as safer-environment interventions, and structural responses, such as decriminalization of sex work can play in improving the health, safety and well-being of SWs.
authors.affiliation: Gender and Sexual Health Initiative, BC Centre for Excellence in HIV/AIDS, St. Paul's Hospital, Vancouver, Canada; Department of Medicine, Faculty of Medicine, University of British Columbia, Vancouver, Canada. Electronic address: kdeering@cfenet.ubc.ca.
authors.forename: Kathleen N
authors.initials: KN
authors.lastname: Deering
authors.affiliation: Gender and Sexual Health Initiative, BC Centre for Excellence in HIV/AIDS, St. Paul's Hospital, Vancouver, Canada; Vancouver Island Health Authority, Victoria, Canada.
authors.forename: Melanie
authors.initials: M
authors.lastname: Rusch
authors.affiliation: Gender and Sexual Health Initiative, BC Centre for Excellence in HIV/AIDS, St. Paul's Hospital, Vancouver, Canada; Department of Geography, Faculty of Environment, Simon Fraser University, Burnaby, Canada.
authors.forename: Ofer
authors.initials: O
authors.lastname: Amram
authors.affiliation: Gender and Sexual Health Initiative, BC Centre for Excellence in HIV/AIDS, St. Paul's Hospital, Vancouver, Canada; School of Population and Public Health, Faculty of Medicine, University of British Columbia, Vancouver, Canada.
authors.forename: Jill
authors.initials: J
authors.lastname: Chettiar
authors.affiliation: Gender and Sexual Health Initiative, BC Centre for Excellence in HIV/AIDS, St. Paul's Hospital, Vancouver, Canada.
authors.forename: Paul
authors.initials: P
authors.lastname: Nguyen
authors.affiliation: School of Public Health, Faculty of Medicine, University of Saskatchewan, Saskatoon, Canada.
authors.forename: Cindy X
authors.initials: CX
authors.lastname: Feng
authors.affiliation: Gender and Sexual Health Initiative, BC Centre for Excellence in HIV/AIDS, St. Paul's Hospital, Vancouver, Canada; Department of Medicine, Faculty of Medicine, University of British Columbia, Vancouver, Canada; School of Population and Public Health, Faculty of Medicine, University of British Columbia, Vancouver, Canada.
authors.forename: Kate
authors.initials: K
authors.lastname: Shannon
mesh_terms: D000328:Adult; D001955:British Columbia / Q000453:epidemiology; D015331:Cohort Studies; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D016015:Logistic Models; D008137:Longitudinal Studies; D015999:Multivariate Analysis; D010865:Pilot Projects; D011446:Prospective Studies; D012111:Residence Characteristics / Q000706:statistics & numerical data; D012306:Risk; D011477:Sex Work / Q000706:statistics & numerical data*; D060386:Sex Workers / Q000706:statistics & numerical data*; D012725:Sexual Behavior / Q000706:statistics & numerical data*; D062206:Spatial Analysis; D019966:Substance-Related Disorders / Q000453:epidemiology*
keywords: Drug use; HIV risk; Sex work; Sex workers; Spatial analysis