Tobacco smoking was a significant risk factor for recurrent suicide attempts among patients with bipolar disorder, according to cohort study data published in the Journal of Affective Disorders.
Investigators conducted a cross-sectional study of patients who presented to specialized clinics in Norway and France. Participants were adults (aged ≥18 years) with a diagnosis of bipolar disorder type I or type II. Both Norwegian and French participants were assessed for bipolar disorder characteristics, prior suicide attempts, and substance use disorders (SUDs). Patients were classified as having no, single, or recurrent (≥2) suicide attempts. In addition, 5 SUD groups were developed on the basis of reported substance use patterns: no substance use, tobacco use only, tobacco use with alcohol use disorder (AUD), tobacco use with cannabis use disorder (CUD), and tobacco use with both AUD and CUD. Multinomial logistic regression was performed to identify which substance use patterns correlated with recurring suicide attempts.
The final study cohort comprised 916 patients across France and Norway, among whom 59% were women and 74% had bipolar disorder type I. Of 338 (37%) patients who reported at least 1 suicide attempt, 173 (51%) reported recurrence. SUD groups consisting of comorbid tobacco smoking in addition to another SUD displayed the strongest association with suicide attempts. Specifically, tobacco smoking with AUD (odds ratio [OR], 3.58; 95% CI, 1.94-6.59) and tobacco smoking with CUD (OR, 2.65; 95% CI, 1.15-6.1) were associated with significantly greater odds of recurrent suicide attempts when compared with no substance use. Tobacco smoking only was associated with greater odds of recurrent suicide attempts (OR, 1.75; 95% CI, 1.16-2.63), although at a lesser magnitude. Tobacco use with AUD, CUD, or both was associated with increased odds of 1 lifetime suicide attempt. However, tobacco smoking combined with both AUD and CUD did not increase the odds of recurrent suicide attempts.
Tobacco smoking, both independently and in the presence of other SUDs, was significantly associated with recurrent suicide attempts in patients with bipolar disorder. Screening for tobacco use in clinical practice is thus important for identifying patients at high risk for suicidality. Further research that investigates substance use in tandem with other suicidality risk factors, such as childhood trauma, anxiety, and personality disorders, is necessary to expand on these findings.
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