Common Methods of Suicide and Self-Inflicted Poisoning/Injury by Individuals With Major Depressive Disorder and Bipolar Disorder: A Nationwide Inpatient Sample Analysis.

Objective: Individuals with major depressive disorder (MDD) and bipolar disorder (BD) are at increased risk of suicide. The objective of this study was to examine the prevalence of different methods of suicide and self-inflicted poisoning/injury in individuals with MDD or BD. Methods: This study used a US National Inpatient Sample dataset from years 2012-2015. Data were collected from discharge records of patients aged ≥ 18 years admitted for MDD or BPD. The prevalence of different methods of suicide and self-inflicted poisoning/injury was evaluated. Highly prevalent subtypes of depression and bipolar disorder among the 2 groups were investigated, and psychiatric comorbidities were compared. Results: We identified 13,556 unweighted records of patients admitted to the hospital for MDD diagnosis, and 6,506 unweighted records of patients admitted for BD diagnosis. Suicide and self-inflicted poisoning/injury by cutting instrument was highly prevalent among both groups, with a greater prevalence among patients with BD compared to MDD (35.5% vs 30.8%, P < .001). Use of tranquilizers/other psychotropic agents (29.2% vs 29.4%, P = .72) and other specified drugs and medicinal substances (14.3% vs 14.0%, P = .546) was high among both groups; however, there was no significant difference. Analgesics (16.7% vs 11%, P = .000), other sedatives and hypnotics (4.9% vs 3.7%, P < .001), other and unspecified solid and liquid substances (3.9% vs 3.3%, P = .037), and hanging by strangulation and suffocation (3.7% vs 2.5%, P < .001) were more prevalent in patients in the MDD group. Conclusions: The results indicate that it is critical to investigate and understand the methods used by individuals with MDD and BD to commit suicide. Restricting access to the most prevalent forms of self-injury could be a practical suicide prevention approach.