Is the Psychotic Depression Assessment Scale a useful diagnostic tool? The CRESCEND study

Background The Psychotic Depression Assessment Scale (PDAS) has been validated as a method of assessing the severity and treatment outcomes of psychotic depression (PD). We aimed to compare the results of the PDAS in PD and non-psychotic depression (non-PD) patients and validate the PDAS as a diagnostic tool for PD. Methods We included 53 patients with PD and 441 with non-PD who participated in the Clinical Research Center for Depression study in South Korea. In addition to the PDAS, psychometric tools including the HAMD ₁₇, HAMA, BPRS, CGI-S, SOFAS, SSI-Beck, WHOQOL-BREF, AUDIT, and FTND were used to assess, respectively, depression, anxiety, overall symptoms, global severity, social functioning, suicidal ideation, quality of life, alcohol use, and nicotine use. Results After adjusting for age and total HAMD₁₇ score, PD patients had higher scores for depressive mood, hallucinations, unusual thought content, suspiciousness, blunted affect, and emotional withdrawal on the PDAS and higher total scores on the SSI-Beck than non-PD patients. Binary logistic regression identified hallucinatory behavior and emotional withdrawal as predictors of PD. Receiver operating characteristic analysis showed that emotional withdrawal could be used to differentiate psychotic from non-psychotic depression. Limitations The inter-rater reliability for psychometric assessments was not evaluated. Conclusions In addition to assessing the severity and treatment outcomes of PD, PDAS can help in the diagnosis of PD.