Prediction of suicidal behavior using self-reported suicidal ideation among patients with bipolar disorder

People with bipolar disorder have elevated suicide risk. We estimated the ability of the Patient Health Questionnaire (PHQ9) to predict suicide outcomes for outpatients with bipolar disorder.

Visits by adults with bipolar disorder who completed a PHQ9 were identified using electronic health record (EHR) data. Bipolar diagnoses and suicide attempts were ascertained from EHR and claims data, and suicide deaths from state and federal records. Depression severity was assessed via the first eight items of the PHQ9, while suicidal ideation was assessed by the ninth item.

37,243 patients made 126,483 visits. Patients reported at least moderate symptoms of depression in 49% and suicidal ideation in 30% of visits. Risk of suicide attempt was 4.21% in the subsequent 90 days for those reporting nearly daily suicidal ideation compared to 0.74% in those reporting none. Patients with nearly daily suicidal ideation were 3.85 (95% CI 3.32-4.47) times more likely to attempt suicide and 13.78 (95% CI 6.56-28.94) times more likely to die by suicide in the subsequent 90 days than patients reporting none. Patients with self-harm in the last year were 8.86 (95% 7.84-10.02) times more likely to attempt suicide in the subsequent 90 days than those without.

Our sample was limited to patients completing the PHQ9 and did not include data on some important social risk or protective factors.

The PHQ9 was a robust predictor of suicide. Suicidal ideation reported on the PHQ9 should be considered a strong indicator of suicide risk and prompt further evaluation.