Many studies have found cross-sectional and prospective associations of suicide with current smoking; few have failed to find this association. The best studies using nationally-representative samples, as well as prospective designs with long-term follow-ups, have almost uniformly found the two associated (Breslau et al. 2005; Doll et al. 1994; Iwasaki et al. 2005; Leistikow et al. 2000; Miller et al. 2000b; Miller et al. 2000a; Tverdal et al. 1993). The association was present whether suicidal thoughts, plans or completions were used as the dependent variable. The odds ratios and relative risks typically were greater than 2.0. In several studies, the risk persisted even after major depression, alcohol/drug abuse, other psychiatric disorders, or other confounders were controlled for.
