Led by adolescent medicine specialist Dr. Laura P. Richardson the research team tested the PHQ-9 as a screening tool for depression in 442 teenagers, age 13-17, who were patients at Group Health. The test is brief, available free of charge, easy to score and understand, and proven in adults to find major depression that fits standard, diagnostic criteria. This study, the first to assess the screening tool in teens, is in the November 2010 Pediatrics.
“This is important not only because depression is relatively common among adolescents, but also because we have effective treatment for them,” said Richardson. She is an associate professor of pediatrics at the UW, an adolescent medicine specialist at Seattle Children’s, and an affiliate investigator at Group Health Research Institute. “Primary care clinicians are advised to screen teens for depression,” she said, “and they need a convenient tool like this.” The team of researchers were from the Group Health, Children’s and the UW
The team compared the PHQ-9 to the more labor-intensive gold standard, an independent structured mental health interview called the Child Diagnostic Interview Schedule 4 (DISC-IV), and to published data on use of the screening test in adults.
They found that the PHQ-9 had a sensitivity (89.5%) and specificity (77.5%) in teens are similar to those in adults.
Sensitivity is a measure of a test’s ability to correctly identify people who have the disease in question, or a true positive. Specificity measures how accurately a test identifies people who don’t have the condition, or a true negative.
They found, however, that the best cut point for maximizing the PHQ-9 screening test’s sensitivity without losing specificity is higher among teens than in adults. A cut point is a mark above which test results are considered to indicate disease, and below which the results are considered normal. A cut point can be adjusted for different clinical situations depending on whether the goal is to reduce false positives or false negatives.
The team interpreted that their study data showed that the PHQ-9 is a suitable choice for health-care professionals and researchers who want to screen for depression in teens in primary care.