Validation of the Patient Health Questionnaire-2 (PHQ-2) in Detecting Depression Among Older Adults.

Objectives: Depression screening tools like the Patient Health Questionnaire-2 (PHQ-2) are commonly used to detect depression. However, its performance in elderly populations has been less extensively studied compared to its broader adult use. This study evaluates the PHQ-2's ability to screen for depression in older adults. Methods: A cross-sectional study was conducted by enrolling 320 elderly individuals (≥ 65 years) from a geriatric outpatient service from May 2023 to July 2024. The sample was randomly split into a validation group and a test group. The discriminatory power of PHQ-2 was evaluated by comparing it to the Geriatric Depression Scale (GDS). Results: The PHQ-2 demonstrated good discriminatory ability, with a Receiver Operating Characteristic Area Under the Curve (AUC) of 0.802 (95% CI: 0.703-0.901) in the validation group. The optimal cutoff for the PHQ-2 was 3 points, yielding a sensitivity of 71% and accuracy of 78%. The model showed high specificity (80%) and negative predictive value (93%), suggesting that few depressed individuals would go undetected. These findings were consistent in the test group (AUC: 0.789). Conclusions: The PHQ-2 is a reliable and efficient tool for screening depression in older adults, with strong diagnostic performance and ease of use. This study supports its application in primary care settings, facilitating timely referrals for further evaluation.