title: Concurrent crack and powder cocaine users from Sao Paulo: do they represent a different group?
abstract: BACKGROUND
  Cocaine abuse is a serious and socially damaging illegal drug problem. Different routes of administration are associated with a specific progression of use, different degrees of abuse liability, propensity for dependence and treatment response. There have been relatively few studies comparing different cocaine users groups and no studies into the characterization of the group of individuals reporting concurrent use of powder cocaine and crack cocaine.
  
  
  METHODS
  Six hundred and ninety-nine cocaine users were assessed during the period August 1997 to October 1998 in one outpatient and six inpatient clinics located in the São Paulo, Brazil. Patients were interviewed using a structured questionnaire schedule in Portuguese, designed specifically for the Brazilian population. The statistical analyses were performed using either ANOVA or a chi-squared test and focusing on their preferred form of use/route of administration and other variables.
  
  
  RESULTS
  For 83% of the variables tested in this study, the Dual Users subgroup (using both powder and crack cocaine) demonstrated statistical differences from the single drug user subgroups. Those differences include the initiation of cocaine, the abuse of other illicit drugs, and rates of criminal history.
  
  
  CONCLUSIONS
  These data suggest cocaine-dependent individuals who report use of both powder and crack cocaine are an at least partially, distinct subgroup. However, further studies will be necessary to confirm this and to determine if they also show a different treatment response.
authors.affiliation: Department of Psychiatry, University of São Paulo Medical School, Brazil. c.guindalini@iop.kcl.ac.uk
authors.forename: Camila
authors.initials: C
authors.lastname: Guindalini
authors.forename: Homero
authors.initials: H
authors.lastname: Vallada
authors.forename: Gerome
authors.initials: G
authors.lastname: Breen
authors.forename: Ronaldo
authors.initials: R
authors.lastname: Laranjeira
mesh_terms: D000280:Administration, Inhalation; D000281:Administration, Intranasal; D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D001938:Brazil / Q000453:epidemiology; D016009:Chi-Square Distribution; D019970:Cocaine-Related Disorders / Q000453:epidemiology*; D016578:Crack Cocaine / Q000008:administration & dosage*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D013287:Illicit Drugs; D008297:Male; D008875:Middle Aged; D010353:Patient Education as Topic; D011208:Powders; D012309:Risk-Taking; D015819:Substance Abuse, Intravenous / Q000453:epidemiology; D011795:Surveys and Questionnaires; D014505:Urban Population
chemical_list: D016578:Crack Cocaine; D013287:Illicit Drugs; D011208:Powders