Differential Associations of the Number of Comorbid Conditions and the Severity of Depression and Anxiety with Self-Reported Suicidal Ideation and Attempt in Major Depressive Disorder and Bipolar Disorder

Background: Previous studies have shown that the number of comorbidity, depression and anxiety severity were associated with increased risk for suicidal behaviors. This study was to investigate the interaction of the number of comorbidities, depression and anxiety severity with self-reported suicidal ideation (SR-SI) and suicide attempt (SA) in patients with major depressive disorder (MDD) or bipolar disorder (BPD). Methods: Three-hundred routine clinical outpatients were diagnosed with the MINI-STEP-BP version at the initial evaluation. Symptom-severity was measured with the 16-item Quick Inventory of Depressive Symptomatology-selfreport (QIDS-SR-16) for depression, Zung Self-Rating Anxiety Scale (SAS), and Clinical Global ImpressionsSeverity (CGI-S) for overall severity. SR-SI was based on QIDS-SR-16 item 12 and SA was based on the MINI suicidality module. Chi-square, Fisher-exact, and linear regression were used for analyses. Results: Of 103 patients with MDD and 147 with BPD, the SR-SI and SA was 23.3% and17.5% for MDD, and 35.0% and 20.4% for BPD, respectively. SR-SI and SA were positively associated with the number of comorbidities in BPD, but not in MDD. SR-SI was positively associated with depressive severity and overall illness severity in both MDD and BPD. However, anxiety severity had a positive linear correlation with SR-SI only in BPD. Anxiety and depressive severity had additive effect on SR-SI in BPD, but had opposite effect on SR-SI in MDD. Conclusion: These data suggest that suicide risk assessment should be disorder specific in patients with a mood disorder. Diagnosing all psychiatric disorders and meausring depression and anxiety severity is essential for managing suicidal behaviors.