Instrument: Patient Health Questionnaire (PHQ-9)
Article: Accuracy of Patient Health Questionnaire-9 (PHQ-9) for screening to detect major depression: Individual participant data meta-analysis.
Appropriateness for Dx: This tool screens patients to detect major depression and bipolar disorders (Levis et al., 2019). It is a well-validated DSM-IV criterion-based measure for assessing severity and monitoring treatment responses. Mental health practitioners use PHQ-9 to track a patient’s improvement of symptoms with treatment. The DSM-5 also recommends the tool for evaluation of depression severity. PHQ-9 is recommended in primary care settings due to its ease of use, validity, reliability, and sensitivity to change over time.
Response to Therapy/Treatment: The PHQ-9 is appropriate for screening bipolar I depression, tracking its symptoms and severity, in addition to tracking the improvement of specific symptoms with treatment according to studies. To score the tool, one tallies the numbers of all the checked responses under not at all, which is 0 to nearly every day, representing 3, and added together to get the total score (Beard et al., 2016).
Psychometrics: The (PHQ-9) is a self-administered nine-item questionnaire version of the PRIME-MD diagnostic tool for mental disorders. The cut-off score for screening for possible depression is 10 and above. A total score can range from 0 to 27. It has a sensitivity to reduce symptoms during treatment of 61% and specificity of 94% in adults (Costantini at al., 2021). The tool’s validity and reliability show that it has sound psychometric properties. It has proved to be adequate, with good internal consistency, as well as, strong and interpretable factor structure. The tool, further, has a high adaptability for individuals with MDD in psychiatric hospital. Levis et al. (2019) assessed the tool’s reliability through test-retest and internal consistency.
Limitations: The instrument’s limitations include its inability to assess differences across patient subgroups. It does not exclude participants already diagnosed as having or being treated for depression. PHQ-9, further, combines accuracy estimates without distinguishing between reference standards.
References
Beard, C., Hsu, K. J., Rifkin, L. S., Busch, A. B., & Björgvinsson, T. (2016). Validation of the PHQ-9 in a psychiatric sample. Journal of Affective Disorders, 193, 267-273. https://doi.org/10.1016/j.jad.2015.12.075
Costantini, L., Pasquarella, C., Odone, A., Colucci, M. E., Costanza, A., Serafini, G., … & Amerio, A. (2021). Screening for depression in primary care with Patient Health Questionnaire-9 (PHQ-9): A systematic review. Journal of Affective Disorders, 279, 473-483. https://doi.org/10.1016/j.jad.2020.09.131
Levis, B., Benedetti, A., & Thombs, B. D. (2019). Accuracy of Patient Health Questionnaire-9 (PHQ-9) for screening to detect major depression: Individual participant data meta-analysis. BMJ, 365. https://doi.org/10.1136/bmj.l1476
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