Suicide is a leading cause of death worldwide. Close to 1 million persons die of suicide each year. The WHO predicts that by 2020 suicide deaths will rise to 1.5 million.1 Completed suicides are largely predicted by the wish to die, thoughts of suicide and unsuccessful previous suicidal attempts,2 making it important to understand the risks posed by suicide-related outcomes (SROs). A history of mental disorders3–5 and particular demographic characteristics (female gender, younger age, unmarried status and unemployment) are putative risk factors for suicide and SRO.2 Smoking, long known as a major risk factor for numerous medical illnesses,6 and recently, for psychiatric outcomes as well,7 8 has received increasing attention for its potential contribution to the risk of completed suicides and SROs.9 Nevertheless, whether the association between smoking and suicidal behaviours is causal or correlational remains unclear.
