Measuring Symptoms of Depression Comparing the Cornell Scale for Depression in Dementia and the Patient Health Questionnaire-9-Observation Version

The purpose of this study was to extend available psychometric data on the Patient Health Questionnaire-9-Observation Version (PHQ-9-OV) by comparing it with the Cornell Scale for Depression in Dementia (CSDD) in a new sample of long-term care residents. Data were collected post intervention in a quasi-experimental storytelling study across six communities. The sample (N = 54) was 87% women with mean age of 84.5, mean CSDD score of 3.96, and mean PHQ-9-OV score of 4.22. Prevalence of depressive symptoms by CSDD criteria was 20.4% and by PRO-9-OV criteria was 40.7%. The CSDD and PHQ-9-OV were well correlated (r(s) = 0.78, p < 0.0001). Neither scale was significantly correlated with depression diagnosis nor antidepressant agent use. Both measures demonstrated adequate reliability. The PHQ-9-OV item scoring and established cut-off points designate a lower threshold than the CSDD to detect clinically significant depressive symptoms. Further study is needed to determine the sensitivity of the PHQ-9-OV in identifying treatment effects.