Patient Health Questionnaire 9 (PHQ-9)

CPP Cohort 4

The Patient Health Questionnaire 9 (PHQ-9)* is a self-report questionnaire for adult caregivers of depressive symptoms and behaviors.  Higher scores indicate greater severity of depression.

Descriptive Statistics: Pre- and post-treatment assessment measure means, standard deviations, and standard errors for the PHQ-9 are listed in the table below, as well as the range of possible scores.

PHQ-9: Descriptive Statistics

1 A score of 10 has been suggested as an adequate cut-point for screening or identifying possible cases where further assessment for depression may be warranted (Kroenke & Spitzer, 2002).

Repeated Measures Analyses: Paired samples t-tests were conducted to examine pre-post group mean differences for the PHQ-9 overall score.  Analyses did not show statistically significant change in the PHQ-9 overall score.

PHQ-9: Paired Sample T-Test

PHQ-9: Pre-Post Mean Scores

Individual Clinically Significant Change: Individual clinically significant change for the PHQ-9 overall score was based on the suggested screening cut-point of 10. At pre-treatment, 7 clients had PHQ-9 overall scores at or above the cut-point of 10. Of note, 5 of these 7 clients were missing the PHQ-9 overall score at post-treatment. Analysis of the clients with post-treatment data showed that the PHQ-9 overall score for 1 of the 2 clients (50%) decreased below the cut-point of 10.


*Kroenke, K., Spitzer, R.L., & Williams, J.B.W. (2001). The PHQ-9: Validity of a Brief Depression Severity Measure. Journal of General Internal Medicine, 16(9), 606–613

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