Drinking and mortality: long-term follow-up of drinking-discordant twin pairs

• Published in: Addiction (Abingdon, England) England), 2016-02, Vol.111 (2), p.245-254
• Main Authors: Sipilä, Pyry, Rose, Richard J., Kaprio, Jaakko
• Format: Article
• Language: English
• Subjects: Adult; Alcohol drinking; Alcohol Drinking - mortality; Alcohol use; alcoholic intoxication; Alcoholic Intoxication - mortality; binge drinking; causality; confounding factors; Female; Finland - epidemiology; Follow-Up Studies; Humans; Male; Middle Aged; Mortality; Risk factors; Smoking - mortality; Tobacco Products - statistics & numerical data; Twins; Twins, Dizygotic - statistics & numerical data; Twins, Monozygotic - statistics & numerical data
• ISSN: 0965-2140; 1360-0443
• DOI: 10.1111/add.13152

Aims To determine if associations of alcohol consumption with all‐cause mortality replicate in discordant monozygotic twin comparisons that control for familial and genetic confounds. Design A 30‐year prospective follow‐up. Setting Population‐based older Finnish twin cohort. Participants 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. Measurements 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. Findings 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.