Does Suicidal Ideation as Measured by the PHQ-9 Predict Suicide Among VA Patients?

OBJECTIVE: Frequency of suicidal ideation in the past two weeks, assessed by item 9 of the nine-item Patient Health Questionnaire (PHQ-9), has been positively associated with suicide mortality among patients in a setting other than the Veterans Health Administration (VHA). To inform suicide prevention activities at the VHA, it is important to evaluate whether item 9 is associated with suicide risk among patients in the VHA system. METHODS: PHQ-9 assessments (N=447,245) conducted by the VHA between October 1, 2009, and September 30, 2010, were collected. National Death Index data were used to ascertain suicide mortality from the date of PHQ-9 assessment through September 30, 2011. Multivariable proportional hazards regressions were used to evaluate associations between responses to item 9 and suicide mortality. RESULTS: After the analyses adjusted for covariates, a response of "several days" for item 9 was associated with a 75% increased risk of suicide (hazard ratio [HR]=1.75, 95% confidence interval [CI]=1.24-2.46), a response of "more than half the days" was associated with a 115% increased risk of suicide (HR=2.15, CI=1.32-3.51), and a response of "nearly every day" was associated with a 185% increased risk of suicide (HR=2.85, CI=1.81-4.47), compared with a response of "not at all." However, 71.6% of suicides during the study period occurred among patients who responded "not at all" to item 9 from their most recent PHQ-9. CONCLUSIONS: Higher levels of suicidal ideation, indicated by item 9 of the PHQ-9, were associated with increased risk of suicide among patients in the VHA system.