title: A latent class analysis of illicit drug abuse/dependence: results from the National Epidemiological Survey on Alcohol and Related Conditions.
abstract: OBJECTIVE
  We examine the co-occurrence of abuse/dependence across different illicit drugs and test associations between these classes and major psychiatric disorders.
  
  
  METHODS
  Latent class analyses were used to characterize polysubstance abuse/dependence (AB/D) in 43 093 individuals who participated in the National Epidemiological Survey on Alcohol and Related Conditions. Multinomial logistic regression was performed to examine the association between the classes of life-time illicit drug AB/D and gender, age and race, as well as life-time Diagnostic and Statistical Manual version IV (DSM-IV) alcohol abuse/dependence, nicotine dependence, major depressive disorder, generalized anxiety disorder, panic disorder, social phobia and antisocial personality disorder.
  
  
  RESULTS
  Five latent classes were identified: no AB/D (class 1: 92.5%), cannabis AB/D only (class 2: 5.8%), stimulants + hallucinogen AB/D (class 3: 0.6%), prescription drug AB/D (class 4: 0.6%) and polysubstance AB/D (class 5: 0.5%). Major depressive disorder and nicotine dependence were associated most strongly with class 5. Anxiety disorders were associated strongly with the prescription drug AB/D class while alcohol AB/D and ASPD were associated with classes 2, 3, 4 and 5 when compared to the reference class (class 1).
  
  
  CONCLUSIONS
  Significant heterogeneity exists in this US population for polysubstance AB/D patterns with evidence for a subgroup with high rates of sedative, tranquilizer and opiate AB/D and a history of anxiety disorders, a stimulant/hallucinogens group, a high-risk group with elevated rates of all psychiatric disorders and a milder cannabis AB/D only group. Replication of such classes across other samples has significant implications, such as characterizing risk groups that may be etiologically diverse.
authors.affiliation: Department of Psychiatry, Washington University School of Medicine, St. Louis, MO 63110, USA. arpana@wustl.edu
authors.forename: Arpana
authors.initials: A
authors.lastname: Agrawal
authors.forename: Michael T
authors.initials: MT
authors.lastname: Lynskey
authors.forename: Pamela A F
authors.initials: PA
authors.lastname: Madden
authors.forename: Kathleen K
authors.initials: KK
authors.lastname: Bucholz
authors.forename: Andrew C
authors.initials: AC
authors.lastname: Heath
mesh_terms: D000293:Adolescent; D000328:Adult; D001008:Anxiety Disorders / Q000453:epidemiology* / Q000523:psychology; D003866:Depressive Disorder / Q000453:epidemiology* / Q000523:psychology; D017831:Diagnosis, Dual (Psychiatry); D039721:Diagnostic and Statistical Manual of Mental Disorders; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D019966:Substance-Related Disorders / Q000453:epidemiology* / Q000523:psychology; D014481:United States / Q000453:epidemiology