Validation of PHQ-2 and PHQ-9 to Screen for Major Depression in the Primary Care Population

We report the largest validation study of the PHQ-2 and PHQ-9, compared with a reference standard interview, undertaken in an exclusively primary care population. The PHQ-2 score or 2 or higher had good sensitivity but poor specificity in detecting major depression. Using a PHQ-2 threshold score of 2 or higher rather than 3 or higher resulted in more depressed patients being correctly identified. A PHQ-9 score of 10 or higher appears to detect more depressed patients than the originally described PHQ-9 scoring for major depression.