Predictors of Suicidal Ideation among Depressed Veterans and the Interpersonal Theory of Suicide

Background
We assessed whether key constructs of the interpersonal theory of suicide were associated with suicidal ideation in depressed US Veterans.

Methods
443 patients of the Veterans Health Administration diagnosed with a depressive disorder completed the Beck Depression Inventory, Interpersonal Support Evaluation List, and Beck Hopelessness Scale, from which we derived measures of burdensomeness, belongingness, and hopelessness consistent with the interpersonal theory of suicide. Measures of active and passive suicidal ideation were constructed from the Beck Suicide Scale and Beck Depression Inventory obtained at baseline and 3-months follow-up. Multivariable logistic regression was used to identify predictors of passive and active suicidal ideation while adjusting for demographic characteristics and somatic-affective symptoms of depression (e.g., anhedonia, insomnia).

Results
Burdensomeness and hopelessness were significantly associated with passive suicidal ideation at baseline and 3 months follow-up, but belongingness and the interaction between belongingness and burdensomeness were not significant predictors as proposed by the interpersonal theory of suicide. Somatic-affective depressive symptoms, but not any of the main effects predicted by the interpersonal theory of suicide or their interactions, were associated with active suicidal ideation at baseline. No factors were consistently associated with active suicidal ideation at 3 months follow-up.

Limitations
The measure of burdensomeness used in this study only partially represents the construct described by the interpersonal theory of suicide.

Conclusion
We found little support for the predictions of the interpersonal theory of suicide. Hopelessness appears to be an important determinant of passive suicidal ideation, while somatic-affective depression symptoms may be a key contributor to active suicidal ideation.