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

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). 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. 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. This study is among mood disorder patients so additional research would be necessary among populations with different conditions. 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. •The sensitivity and specificity of the PHQ-9 suicide item compared to the Columbia-Suicide Severity Rating Scale was >70%•The internal validity of the PHQ-9 suicide item varies by demographic and clinical characteristics•The PHQ-9 suicide item is a modest screening tool of suicide risk