title: Drinking and mortality: long-term follow-up of drinking-discordant twin pairs.
abstract: OBJECTIVE
  To determine if associations of alcohol consumption with all-cause mortality replicate in discordant monozygotic twin comparisons that control for familial and genetic confounds.
  
  
  METHODS
  A 30-year prospective follow-up.
  
  
  METHODS
  Population-based older Finnish twin cohort.
  
  
  METHODS
  Same-sex twins, aged 24-60 years at the end of 1981, without overt comorbidities, completed questionnaires in 1975 and 1981 with response rates of 89 and 84%. A total of 15,607 twins were available for mortality follow-up from the date of returned 1981 questionnaires to 31 December 2011; 14,787 twins with complete information were analysed.
  
  
  METHODS
  Self-reported monthly alcohol consumption, heavy drinking occasions (HDO) and alcohol-induced blackouts. Adjustments for age, gender, marital and smoking status, physical activity, obesity, education and social class.
  
  
  RESULTS
  Among twins as individuals, high levels of monthly alcohol consumption (≥ 259 g/month) associated with earlier mortality [hazard ratio (HR) = 1.63, 95% confidence interval (CI) = 1.47-1.81]. That association was replicated in comparisons of all informatively drinking-discordant twin pairs (HR = 1.91, 95% CI = 1.49-2.45) and within discordant monozygotic (MZ) twin pairs (HR = 2.24, 95% CI = 1.31-3.85), with comparable effect size. Smaller samples of MZ twins discordant for HDO and blackouts limited power; a significant association with mortality was found for multiple blackouts (HR = 2.82, 95% CI = 1.30-6.08), but not for HDO.
  
  
  CONCLUSIONS
  The associations of high levels of monthly alcohol consumption and alcohol-induced blackouts with increased all-cause mortality among Finnish twins cannot be explained by familial or genetic confounds; the explanation appears to be causal.
authors.affiliation: Department of Public Health, University of Helsinki, Helsinki, Finland.
authors.forename: Pyry
authors.initials: P
authors.lastname: Sipilä
authors.affiliation: Department of Psychological and Brain Sciences, Indiana University, Bloomington, Indiana, USA.
authors.forename: Richard J
authors.initials: RJ
authors.lastname: Rose
authors.affiliation: Department of Public Health, University of Helsinki, Helsinki, Finland.|National Institute for Health and Welfare, Helsinki, Finland.|Institute for Molecular Medicine Finland (FIMM), University of Helsinki, Helsinki, Finland.
authors.forename: Jaakko
authors.identifier: http://orcid.org/0000-0002-3716-2455
authors.initials: J
authors.lastname: Kaprio
mesh_terms: D000328:Adult; D000428:Alcohol Drinking / Q000401:mortality*; D000435:Alcoholic Intoxication / Q000401:mortality; D005260:Female; D005387:Finland / Q000453:epidemiology; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D012907:Smoking / Q000401:mortality; D062789:Tobacco Products / Q000706:statistics & numerical data; D014429:Twins, Dizygotic / Q000706:statistics & numerical data; D014430:Twins, Monozygotic / Q000706:statistics & numerical data
keywords: Alcohol drinking; alcoholic intoxication; binge drinking; causality; confounding factors; follow-up studies; mortality; twins