Abstract
PURPOSE: To validate the five-item version of the Perceived Deficits Questionnaire for Depression (PDQ-D-5) for assessing subjective cognitive function in Japanese patients with major depressive disorder (MDD) using data from the PERFORM-J study. PATIENTS AND METHODS: A total of 518 Japanese outpatients diagnosed with MDD were assessed on severity of depressive symptoms, cognitive function, social and work function, and quality of life (QoL) over 6 months following initiation of antidepressant therapy. This post hoc analysis evaluated the internal consistency and convergent validity of the PDQ-D-5 in relation to the original PDQ-D-20. Correlations of scores on these measures were examined at each time point and over time. The same set of analyses was explored between PDQ-D-5 and the Patient Health Questionnaire-nine-item (PHQ-9), Montgomery-Asberg Depression Rating Scale (MADRS), Digit Symbol Substitution Test (DSST), five-level version of EQ-5D (EQ-5D-5L), Sheehan Disability Scale (SDS), and Work Productivity and Activity Impairment (WPAI) questionnaire. RESULTS: PDQ-D-5 scores showed good internal consistency. Strong positive correlations were observed between PDQ-D-5 and PDQ-D-20 at each time point (correlation coefficient: baseline, 0.94; month 1, 0.94; month 2, 0.96; month 6, 0.96) and over time (0.92) (all p < 0.0001). Longitudinally, there were positive correlations between PDQ-D-5 scores versus those on the PHQ-9, MADRS, and SDS. Similarly, negative correlations were noted between PDQ-D-5 scores and EQ-5D-5L and DSST scores to a variable degree. There were moderate positive correlations over time between PDQ-D-5 and all WPAI subscale scores except those on absenteeism. CONCLUSION: PDQ-D-5 scores rated in Japanese patients with MDD were found to adequately represent scores on the PDQ-D-20. The short version also showed associations with several measures of functional outcome, depression severity and QoL. This validates the PDQ-D-5 as a feasible and clinically reliable tool to assess subjective experience on cognition, which is applicable to time-limited consultations. UMIN CLINICAL TRIALS REGISTRY FOR PRIMARY STUDY: UMIN000024320.