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

Consecutive adult patients attending Auckland family practices completed the PHQ-9, after which they completed the Composite International Diagnostic Interview (CIDI) depression reference standard. Sensitivities and specificities for PHQ-2 and PHQ-9 were analyzed.

There were 2,642 patients who completed both the PHQ-9 and the CIDI. Sensitivity and specificity of the PHQ-2 for diagnosing major depression were 86% and 78%, respectively, with a score of 2 or higher and 61% and 92% with a score 3 or higher; for the PHQ-9, they were 74% and 91%, respectively, with a score of 10 or higher. For the PHQ-2 a score of 2 or higher detected more cases of depression than a score of 3 or higher. For the PHQ-9 a score of 10 or higher detected more cases of major depression than the PHQ determination of major depression originally described by Spitzer et al in 1999.