title: Childhood socio-economic status, school failure and drug abuse: a Swedish national cohort study.
abstract: OBJECTIVE
  To investigate whether socio-economic status (SES) in childhood and school failure at 15 years of age predict illicit drug abuse in youth and young adulthood.
  
  
  METHODS
  Register study in a Swedish national cohort born 1973-88 (n = 1,405,763), followed from age 16 to 20-35 years. Cox regression analyses were used to calculate hazard ratios (HR) for any indication of drug abuse.
  
  
  METHODS
  Our outcomes were hospital admissions, death and criminality associated with illicit drug abuse. Data on socio-demographics, school grades and parental psychosocial problems were collected from censuses (1985 and 1990) and national registers. School failure was defined as having mean school grades from the final year in primary school lower than -1 standard deviation and/or no grades in core subjects.
  
  
  RESULTS
  School failure was a strong predictor of illicit drug abuse with an HR of 5.87 (95% CI: 5.76-5.99) after adjustment for age and sex. Childhood SES was associated with illicit drug abuse later in life in a stepwise manner. The lowest stratum had a HR of 2.28 (95% CI: 2.20-2.37) compared with the highest stratum as the reference, when adjusted for other socio-demographic variables. In the fully adjusted model, the effect of SES was greatly attenuated to an HR of 1.23 (95% CI: 1.19-1.28) in the lowest SES category, while the effect of school failure remained high with an HR of 4.22 (95% CI: 4.13-4.31).
  
  
  CONCLUSIONS
  School failure and childhood socio-economic status predict illicit drug abuse independently in youth and young adults in Sweden.
authors.affiliation: Centre for Health Equity Studies, Karolinska Institutet/Stockholm University, Stockholm, Sweden. karl.gauffin@chess.su.se
authors.forename: Karl
authors.initials: K
authors.lastname: Gauffin
authors.forename: Bo
authors.initials: B
authors.lastname: Vinnerljung
authors.forename: Mats
authors.initials: M
authors.lastname: Fridell
authors.forename: Morten
authors.initials: M
authors.lastname: Hesse
authors.forename: Anders
authors.initials: A
authors.lastname: Hjern
mesh_terms: D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D003415:Crime / Q000706:statistics & numerical data; D004522:Educational Status; D005260:Female; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D008297:Male; D012307:Risk Factors; D012959:Socioeconomic Factors; D019966:Substance-Related Disorders / Q000453:epidemiology* / Q000401:mortality / Q000523:psychology; D013548:Sweden; D014477:Underachievement; D055815:Young Adult
keywords: Childhood; Sweden; cohort study; drug abuse; school failure; social inequity; socio-economic status