title: Patterns of cocaine and opioid co-use and polyroutes of administration among street-based cocaine users in Montréal, Canada.
abstract: BACKGROUND
  Effective public health programs aimed at problematic cocaine users are challenged by the fact that they can have complex patterns of drug use with respect to polysubstance use and routes of drug administration. This study was carried out to explore the presence of subgroups of cocaine users on the basis of their concurrent use of opioids and their routes of cocaine and opioid administration, and to determine if subgroups could be differentiated in terms of sociodemographic factors and risk behaviours.
  
  
  METHODS
  Regular cocaine users (≥1 per week) were recruited in low-threshold services located in the Montréal downtown area. The following variables were examined: demographic characteristics, types of drug used, routes of drug administration, and condom use with occasional or commercial sexual partners. Latent class analysis and multinomial logistic regression modeling were carried out.
  
  
  RESULTS
  886 cocaine users were recruited (83.5% male: mean age 35.38 years). A 5-class model was identified: (1) "cocaine smokers" (CSs) (n = 161; membership probability (MP) = 0.183); (2) "cocaine smokers/sniffers" (CSSs) (n = 201; MP = 0.218); (3) "cocaine injectors" (CIs) (n = 207; MP = 0.231); (4) "cocaine-opioid injectors" (COIs) (n = 277; MP = 0.291); (5) "cocaine-opioid polyroute users" (COPs) (n = 40; MP = 0.077). Compared with COIs, other subtypes were significantly different in terms of either age, duration of cocaine use, ethnic background, homelessness, polydrug use or condom use.
  
  
  CONCLUSIONS
  The heterogeneity of consumption patterns supports the importance of offering an array of interventions aimed at problematic cocaine users. These should include the provision of clean injecting and smoking material, the promotion of safe sexual behaviours and the prevention of initiation to drug injection. In the absence of specific treatment, cocaine users should have access to primary health care services and addiction treatment based on innovative behavioural and pharmacological approaches.
authors.affiliation: Université de Sherbrooke, Addiction Research and Study Program, Faculty of Medicine and Health Sciences, Longueuil, Québec, Canada J4K 0A8. elise.roy@usherbrooke.ca
authors.forename: Élise
authors.initials: É
authors.lastname: Roy
authors.forename: Isabelle
authors.initials: I
authors.lastname: Richer
authors.forename: Nelson
authors.initials: N
authors.lastname: Arruda
authors.forename: Jill
authors.initials: J
authors.lastname: Vandermeerschen
authors.forename: Julie
authors.initials: J
authors.lastname: Bruneau
mesh_terms: D000328:Adult; D000367:Age Factors; D000701:Analgesics, Opioid / Q000008:administration & dosage*; D002170:Canada / Q000453:epidemiology; D003042:Cocaine / Q000008:administration & dosage*; D004333:Drug Administration Routes; D055030:Drug Users / Q000523:psychology / Q000706:statistics & numerical data*; D005006:Ethnicity / Q000523:psychology / Q000706:statistics & numerical data; D005260:Female; D006703:Ill-Housed Persons / Q000523:psychology / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D012309:Risk-Taking; D047568:Unsafe Sex / Q000523:psychology / Q000706:statistics & numerical data
chemical_list: D000701:Analgesics, Opioid; D003042:Cocaine