En innføring i depresjonsvurdering med PHQ-9

Assessment of depression is a routine task in clinical practice in Norway. National guidelines (Helsedirektoratet, 2009) recommend the use of measurement instruments in assessment of depression. PHQ-9 is widely used in research and practice. The official PHQ-9 manual provides practical guidance on interpreting test results with the use of clinical cutoff scores and a diagnostic algorithm for DSM-IV. With background from clinical practice and research, we summarize and provide guidance on the practical use of PHQ-9 beyond what the official PHQ-9 manual offers, applied to a Norwegian context. We provide a general introduction to diagnostic assessment of depression and the limited role of measurement instruments in such assessments. We describe how the original diagnostic algorithm can be adapted to ICD-10 criteria, we describe how to apply clinical significance to use PHQ-9 as a feedback instrument to monitor treatment progress, and we describe how to interpret results with missing answers. Finally, we discuss the shortcomings of relying on measurement instruments in assessment of depression and conclude that PHQ-9 is better suited in ordinary practice than other instruments recommended in the national guidelines.