A validation study of PHQ-9 suicide item with the Columbia Suicide Severity Rating Scale in outpatients with mood disorders at National Network of Depression Centers

Background: In the United States, suicide is one of the serious public health problems and a major cause of death. Several researchers and clinical settings use the patient health questionnaires (PHQ-9) to gauge depression and psychological distress among adults and to predict suicide and death. This study aimed to assess the sensitivity, specificity, and predictive potential of suicide Q9 of the PHQ-9 compared to the Columbia-suicide severity rating scale (C-SSRS). Methods: Adults aged 19 or older, identified with a primary mood disorder diagnosis during their initial clinic visit between 2012 and 2020 from the National Network of Depression Centers, were included in the study. The accuracy of the PHQ-9 suicide item was compared with the gold standard, the C-SSRS. Results: Out of 2677 study participants, 31.6 % (n = 846) and 11.65 % (n = 312) had positive responses to the PHQ-9 suicide item and C-SSRS response, respectively. The sensitivity of the PHQ-9 compared to the C-SSR was 74.7 % (95%CI: 69.6 %–79.2 %), specificity 74.1 % (95%CI: 72.3 %–75.8 %), positive predictive value 27.5 % (95%CI: 24.6 %–30.6 %), and negative predictive value 95.7 % (95%CI: 94.7 %–96.5 %). The secondary analysis results showed better validity results of the PHQ-9 suicide item when compared to the suicide ideation item of the C-SSRS. Limitations: This study is among mood disorder patients so additional research would be necessary among populations with different conditions. Conclusion: For initial suicide screening, the PHQ-9 suicide item would over identify patients as at risk for suicide and the C-SSRS should be used mood disorder clinics to identify suicide risk.