Dynamic Shortening of Psychometric Questionnaires: A Focus on PHQ-9

The Patient Health Questionnaire-9 (PHQ-9) is a widely utilized assessment tool designed to screen for and measure the severity of depression. Recent research has explored the viability of shorter versions of the questionnaire, such as the PHQ-DEP-4 and PHQ-2, particularly for screening depressed individuals before clinical trials. However, these short tests use a fixed number of questions. This study investigated whether there is merit in posing a dynamic number of questions in screening individuals for depressive symptomatology. To address this, our study focuses on creating a short and dynamic version of the PHQ-9. Our approach utilizes dynamic thresholds tailored to individual responses to predict depression. Optimal thresholds are determined by minimizing the number of questions while simultaneously maximizing the Youden index. Results indicate the Dynamic PHQ-9 model demonstrated superior discrimination ability achieving highest Youden index, sensitivity, and specificity.