Reliability and validity of the Chinese version of the Patient Health Questionnaire-9 (C-PHQ-9) in patients with psoriasis: a cross-sectional study

ObjectiveTo evaluate the clinical reliability and validity of the Chinese version of the Patient Health Questionnaire-9 (C-PHQ-9) in patients with psoriasis.DesignCross-sectional study.SettingTertiary care centre.ParticipantsPatients with psoriasis who have not been diagnosed with depression (n=148; mean age 43.37±17.46 years; 31.19% female).Primary and secondary outcome measuresThe primary outcome measures considered in this study were the C-PHQ-9 and the Hamilton Depression Scale (HAMD). The American Diagnostic and Statistical Manual of Mental Disorders Fifth Edition (DSM-V) was used as the gold standard for the diagnosis of depression. Cronbach’s α and test–retest reliability after 1 week were evaluated using reliability analysis, and criterion and structural validity were assessed using validity analysis. Receiver operating characteristic (ROC) analysis was performed to identify the best demarcation score and diagnostic accuracy.ResultsCompared with DSM-V (27.27%), both C-PHQ-9 (39.19%) and HAMD (31.01%) had higher rates for detecting depression. The mean completion time for C-PHQ-9 evaluation (2.02±0.84 min) was significantly less than that for HAMD (23.37±3.21 min, p