title: An estimate of the prevalence of drug misuse in Liverpool and a spatial analysis of known addiction.
abstract: BACKGROUND
  The objective of this study was to determine the prevalence and distribution of opiate and cocaine misuse in the City of Liverpool in 1991. The databases included residents of the city using opiates or cocaine, who were known to the Drug Dependency Units or the Infectious Diseases Unit, or who were arrested for possession of drugs in 1991.
  
  
  METHODS
  A three-sample log-linear capture-recapture method was applied to databases containing details of drug users with City of Liverpool postcodes, to determine the prevalence of drug misuse in 1991. Linear regression analysis was performed to correlate the prevalence of known drug misuse with indices of material deprivation in each electoral ward.
  
  
  RESULTS
  Data on 1427 individuals were analysed, producing an estimate of the drug-using population of 2344 [95 per cent confidence interval (CI) = 1972-2716] and a period prevalence of 5.2 per 1000 [95 per cent CI = (4.5-6.0) per 1000]. In the 15-29 year age group, the prevalence of drug abuse was 16.9 per 1000 [95 per cent CI = (13.9-19.9) per 1000]. There was a negative interdependence between the police and Drug Dependency Unit databases with attenders at the Unit being 7.2 (95 per cent CI = 4.6-11.4) times less likely to be arrested for possession than non-attenders. There was a strong correlation between the distribution of known drug use and material deprivation, as measured by the Townsend index (r = 0.75; p < 0.001).
  
  
  CONCLUSIONS
  The capture-recapture method allows the prevalence of drug misuse to be estimated and provides more meaningful information than is available from the notification system. The study suggests that people in contact with drug services are less likely to commit crimes of possession of class A drugs than those not in contact with drug services. There is a strong association between drug abuse and deprivation, and therefore the purchasing of services for drug misusers should be focused on areas of deprivation.
authors.affiliation: North West Regional Health Authority, Birchwood, Warrington.
authors.forename: N F
authors.initials: NF
authors.lastname: Squires
authors.forename: N J
authors.initials: NJ
authors.lastname: Beeching
authors.forename: B J
authors.initials: BJ
authors.lastname: Schlecht
authors.forename: S M
authors.initials: SM
authors.lastname: Ruben
mesh_terms: D000293:Adolescent; D000328:Adult; D003042:Cocaine; D016001:Confidence Intervals; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D016014:Linear Models; D008297:Male; D009293:Opioid-Related Disorders / Q000453:epidemiology*; D011203:Poverty; D015995:Prevalence; D012044:Regression Analysis; D014478:Unemployment; D014505:Urban Population
chemical_list: D003042:Cocaine