Measuring Population-Level Adolescent Mental Health Using a Single-Item Indicator of Experiences of Sadness and Hopelessness: Cross-Sectional Study.

Associations between having felt sad or hopeless for 2 weeks or more and moderate to severe depressive symptoms, frequent mental distress, and functional limitation due to poor mental health suggest the single-item indicator may represent relevant symptoms associated with poor mental health and be associated with unmet health needs. Findings suggest the single-item indicator provides a population-level snapshot of adolescent experiences of poor mental health.