title: Probability and predictors of the cannabis gateway effect: a national study.
abstract: BACKGROUND
  While several studies have shown a high association between cannabis use and use of other illicit drugs, the predictors of progression from cannabis to other illicit drugs remain largely unknown. This study aims to estimate the cumulative probability of progression to illicit drug use among individuals with lifetime history of cannabis use, and to identify predictors of progression from cannabis use to other illicit drugs use.
  
  
  METHODS
  Analyses were conducted on the sub-sample of participants in Wave 1 of the National Epidemiological Survey on Alcohol and Related Conditions (NESARC) who started cannabis use before using any other drug (n=6624). Estimated projections of the cumulative probability of progression from cannabis use to use of any other illegal drug use in the general population were obtained by the standard actuarial method. Univariate and multivariable survival analyses with time-varying covariates were implemented to identify predictors of progression to any drug use.
  
  
  RESULTS
  Lifetime cumulative probability estimates indicated that 44.7% of individuals with lifetime cannabis use progressed to other illicit drug use at some time in their lives. Several sociodemographic characteristics, internalizing and externalizing psychiatric disorders and indicators of substance use severity predicted progression from cannabis use to other illicit drugs use.
  
  
  CONCLUSIONS
  A large proportion of individuals who use cannabis go on to use other illegal drugs. The increased risk of progression from cannabis use to other illicit drugs use among individuals with mental disorders underscores the importance of considering the benefits and adverse effects of changes in cannabis regulations and of developing prevention and treatment strategies directed at curtailing cannabis use in these populations.
authors.affiliation: Department of Psychology, University of Oviedo, Plaza Feijoo, s/n, 33003 Oviedo, Spain; New York State Psychiatric Institute, Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, 10032 NY, United States. Electronic address: secades@uniovi.es.
authors.forename: Roberto
authors.initials: R
authors.lastname: Secades-Villa
authors.affiliation: Department of Psychology, University of Oviedo, Plaza Feijoo, s/n, 33003 Oviedo, Spain; New York State Psychiatric Institute, Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, 10032 NY, United States.
authors.forename: Olaya
authors.initials: O
authors.lastname: Garcia-Rodríguez
authors.affiliation: New York State Psychiatric Institute, Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, 10032 NY, United States.
authors.forename: Chelsea J
authors.initials: CJ
authors.lastname: Jin
authors.affiliation: New York State Psychiatric Institute, Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, 10032 NY, United States.
authors.forename: Shuai
authors.initials: S
authors.lastname: Wang
authors.affiliation: New York State Psychiatric Institute, Department of Psychiatry, College of Physicians and Surgeons, Columbia University, New York, 10032 NY, United States.
authors.forename: Carlos
authors.initials: C
authors.lastname: Blanco
mesh_terms: D000293:Adolescent; D000328:Adult; D005260:Female; D006306:Health Surveys; D006801:Humans; D013287:Illicit Drugs; D008297:Male; D008385:Marijuana Smoking / Q000453:epidemiology*; D001523:Mental Disorders / Q000453:epidemiology*; D008875:Middle Aged; D011336:Probability; D019966:Substance-Related Disorders / Q000453:epidemiology*; D014481:United States / Q000453:epidemiology; D055815:Young Adult
chemical_list: D013287:Illicit Drugs
keywords: Cannabis; Gateway; Other illicit drugs; Progression