Screening depressive episodes in adolescents. Validation of the Patient Health Questionnaire-9 (PHQ-9)

Background: There is a paucity of validated instruments for screening depression in adolescent populations in Chile. Aim: To determine the diagnostic accuracy of the adolescent version of Patient Health Questionnaire-9 (PHQ-9). Material and Methods: The PHQ-9 was transculturally adapted and administered to adolescents aged 15 to 19 years residing in Santiago de Chile, who were then evaluated with a semi structured interview (Kiddie-Schedule for Affective Disorders and Schizophrenia-Present and Lifetime Version or K-SADS-PL) and the Beck Depression Inventory. Internal validity, concurrent validity, and discriminatory power of the PHQ-9 were analyzed. Results: We evaluated 245 adolescents aged 16.2 +/- 1 years (71% females). Two hundred and ten presented with a depressive episode and 35 were healthy. The sensitivity and specificity of the scale were 86.2 and 82.9% for 11 points, with a positive likelihood ratio of 5.02. Conclusions: The PHQ-9 is sensitive and specific enough to be used as a screening tool in adolescents with suspected depression. At a 11-point cut-off score as proposed, the likelihood to find a positive result in a subject with depression is five times higher.