Tobacco smoking has been associated with suicide in a number of studies (Hemenway et al. 1993; Tverdal et al. 1993; Doll et al. 1994; Miller et al. 2000a; Tanskanen et al. 2000; Iwasaki et al. 2005; Lucas et al. 2013; Schneider et al. 2014), but because smokers have higher prevalence of chronic somatic, psychiatric and addictive disorders that confer independent risk for suicide (Grant et al. 2004; Hasin et al. 2005; Hughes, 2008; Lawrence et al. 2009), interpretation of this association remains highly controversial. Some studies have reported that the association between tobacco smoking and completed suicide is independent of potential confounds such as co-morbid psychiatric illness (e.g. depression) and excessive alcohol use (Tanskanen et al. 2000; Iwasaki et al. 2005; Lucas et al. 2013; Schneider et al. 2014), while others report that the association is due to heavy alcohol use and psychiatric co-morbidity (Hemmingsson & Kriebel, 2003). Consensus on the nature of the association is needed and could influence suicide risk assessment and broaden our understanding of the harms of tobacco smoking. To reduce the public health burden of
