title: Estimating trends in the prevalence of problematic cocaine use (1999-2008).
abstract: OBJECTIVE
  To examine trends in the prevalence of problematic cocaine use in a large city and describe the problems encountered when estimating these trends using capture-recapture techniques based on secondary data
  
  
  METHODS
  We used clinical data on accident and emergency department episodes at four university hospitals in Barcelona (Spain) between 1999 and 2008 (3 capture periods per year). Users were categorized into two subgroups depending on concomitant heroin use (cocaine plus heroin, cocaine without heroin).
  
  
  RESULTS
  The mean age of users was 34 years and 25% were women (2008). The mean number of episodes per user differed between drug subgroups and over time. The estimated total number of cocaine users increased from 6,028 (95% confidence interval [95%CI]: 4,086-9,327) in 1999 to 22,640 (95%CI: 14,001-37,500) in 2006, but decreased thereafter. The prevalence of problematic use of cocaine plus heroin was stable throughout the study. Thus, trends in the prevalence of problematic cocaine use differed depending on concomitant heroin use.
  
  
  CONCLUSIONS
  Our results are consistent with those provided by health surveys and treatment registries. They also highlight the pitfalls of applying the capture-recapture approach to secondary data, and the need for a better understanding of how information is collected and changes over time.
authors.affiliation: Agència de Salut Pública de Barcelona, Barcelona, Spain; CIBER de Epidemiología y Salud Pública (CIBERESP), Spain; Departament de Psicobiologia i Metodologia de les Ciències de la Salut, Universitat Autònoma de Barcelona, Bellaterra (Barcelona), Spain.
authors.forename: Albert
authors.initials: A
authors.lastname: Espelt
authors.affiliation: CIBER de Epidemiología y Salud Pública (CIBERESP), Spain; Drug Abuse Epidemiology Research Group, Institut Municipal d'Investigació Mèdica (IMIM-Hospital del Mar), Barcelona, Spain. Electronic address: adomingo@imim.es.
authors.forename: Antònia
authors.initials: A
authors.lastname: Domingo-Salvany
authors.affiliation: Drug Abuse Epidemiology Research Group, Institut Municipal d'Investigació Mèdica (IMIM-Hospital del Mar), Barcelona, Spain.
authors.forename: Albert
authors.initials: A
authors.lastname: Sánchez-Niubó
authors.affiliation: Agència de Salut Pública de Barcelona, Barcelona, Spain; CIBER de Epidemiología y Salud Pública (CIBERESP), Spain.
authors.forename: Marc
authors.initials: M
authors.lastname: Marí-Dell'Olmo
authors.affiliation: Agència de Salut Pública de Barcelona, Barcelona, Spain; CIBER de Epidemiología y Salud Pública (CIBERESP), Spain.
authors.forename: M Teresa
authors.initials: MT
authors.lastname: Brugal
mesh_terms: D000293:Adolescent; D000328:Adult; D019970:Cocaine-Related Disorders / Q000453:epidemiology*; D015897:Comorbidity; D003430:Cross-Sectional Studies / Q000379:methods; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data; D005260:Female; D006556:Heroin Dependence / Q000453:epidemiology; D006801:Humans; D008297:Male; D009017:Morbidity / Q000639:trends; D015995:Prevalence; D013030:Spain / Q000453:epidemiology; D014505:Urban Population; D055815:Young Adult
keywords: Accident and emergency service; Cocaine; Cocaína; Epidemiology methods; Hospital; Métodos epidemiológicos; Prevalence; Prevalencia; Servicio de emergencias