Association of alcohol and drug use disorders and completed suicide: an empirical review of cohort studies

Abstract

Background: This study updated and expanded upon Harris and Barraclough's empirical review [Harris, E.C., Barraclough, B., 1997. Suicide as an outcome for mental disorders. A meta-analysis, Br. J. Psychiatry 170, 205–228] of retrospective and prospective cohort studies of alcohol and drug use disorders and suicide. Method: Studies presenting data on alcohol and drug use disorders and suicide originally identified by Harris and Barraclough were used in this study. To find additional studies, (1) the location of English language reports on MEDLINE (1994–2002) were identified with the search terms ‘substance-disorders’ with ‘mortality’ and ‘follow-up’, (2) read throughs were conducted of four prominent alcohol and drug specialty journals from 1966 through 2002, and (3) the reference sections of studies that met criteria were searched for additional reports. This strategy yielded 42 new studies meeting eligibility criteria. Results: The estimated standardized mortality ratios (SMR; 95% confidence interval) for suicide were as follows: alcohol use disorder (979; 95% CI 898–1065; p < 0.001), opioid use disorder (1351; 95% CI 1047–1715; p < 0.001), intravenous drug use (1373; 95% CI 1029–1796; p < 0.001), mixed drug use (1685; 95% CI 1473–1920; p < 0.001), heavy drinking (351; 95% CI 251–478; p < 0.001). SMR estimates stratified by sex were also calculated. Conclusions: Additional studies on the association of suicide and mixed drug use, heavy drinking, and alcohol use disorders in women augmented the findings of Harris and Barraclough, along with a novel estimate for intravenous drug use, a byproduct of intensive research on HIV in the past decade. There is a large empirical literature on alcohol use disorders and suicide and a moderate literature on suicide and opioid use disorders and IV drug use. There remains limited prospective data on the association of suicide and other drug use disorders (e.g., cocaine, cannabis).