The PHQ-9 was compared to a gold standard structured mental health interview. The point that maximized sensitivity and specificity was a score of ≥11. However a score of ≥10 (the standard cut-off for adults) had only a slightly lower specificity and might also be a reasonable choice in systems where adults are also being seen and a single diagnostic cut-off is preferred. Results are provided below:
Among “false positive youth” (youth who were positive on the PHQ-9 but did meet criteria for current major depression), 82% met criteria for at least one other mental health disorder.
Access the article at http://www.ncbi.nlm.nih.gov/pubmed/21041282
Access to the PHQ-9 can be found here: http://www.integration.samhsa.gov/images/res/PHQ%20-%20Questions.pdf