Validation and Functional Relevance of the Short Form of the Perceived Deficits Questionnaire for Depression for Japanese Patients with Major Depressive Disorder

Figures & data

Figure 1 Total scores of (A) PDQ-D-5 and (B) PDQ-D-20 at baseline and over the 6 months following initiation of antidepressant medication. Data show the median and interquartile range (IQR) scores at baseline and at 1, 2, and 6 months after the initiation of antidepressant medication. The additional symbol inside the box shows the mean score at each time point. The upper error bar shows (Q3 [max]) at each time point. If outliers are present (shown as symbols above Q3), the upper error bar will be (Q3; Q3 + 1.5 × IQR), where IQR = Q3 − Q1. The lower error bars show (Q1 [min]).

Abbreviations: IQR, interquartile range; max, maximum; min, minimum; PDQ-D-5, Perceived Deficits Questionnaire for Depression–five-item; PDQ-D-20, Perceived Deficits Questionnaire for Depression–20-item; Q, quartile.

Figure 2 Correlation between the PDQ-D-20 and PDQ-D-5 total scores at baseline and over the 6 months following the initiation of antidepressant medication. Data show PDQ-D-20 total scores against PDQ-D-5 total scores plotted for each patient at (A) baseline, (B) month 1, (C) month 2, and (D) month 6. The correlation coefficients between the PDQ-D-20 and PDQ-D-5 are shown at each time point, where an absolute value > 0.7, 0.4–0.7, or < 0.4 indicates a strong, moderate, or weak correlation, respectively.

Abbreviations: PDQ-D-5, Perceived Deficits Questionnaire for Depression–five-item; PDQ-D-20, Perceived Deficits Questionnaire for Depression–20-item.

Table 1 Pearson Correlation Coefficients Between WPAI Subscale Scores and PDQ-D-5 Total Scores

WPAI Subscale	Baseline		Month 1		Month 2		Month 6		rmcorr (n)
	CC (n)	p value	CC (n)	p value	CC (n)	p value	CC (n)	p value
Absenteeism	0.00 (347)	0.94	0.09 (222)	0.18	0.17 (219)	0.01	0.21 (177)	0.004	−0.04 (965)
Presenteeism	0.50 (290)	< 0.0001	0.63 (161)	< 0.0001	0.61 (168)	< 0.0001	0.56 (155)	< 0.0001	0.51 (774)
Overall work impairment	0.47 (285)	< 0.0001	0.55 (158)	< 0.0001	0.58 (167)	< 0.0001	0.58 (152)	< 0.0001	0.51 (762)
Impairment of general activity	0.43 (510)	< 0.0001	0.50 (400)	< 0.0001	0.62 (390)	< 0.0001	0.63 (329)	< 0.0001	0.54 (1629)

Notes: To integrate all visits in the analyses, rmcorr was used to account for non-independence among repeated measures. A correlation coefficient with an absolute value 0.4–0.7 represents a moderate correlation (blue), while < 0.4 (white) represents a weak correlation. n is the number of observations used for each correlation. P values are statistically significant at the level of 0.001.

Abbreviations: CC, correlations coefficient; rmcorr, repeated measures correlation; PDQ-D-5, Perceived Deficits Questionnaire for Depression–five-item; WPAI, Work Productivity and Activity Impairment.

Table 2 Correlation Matrices for PDQ-D-5, MADRS, EQ-5D-5L, SDS, DSST, and PHQ-9 Scores

(A) Baseline
Assessment	PDQ-D-5 (n)	MADRS	EQ-5D-5L	SDS	DSST	PHQ-9
PDQ-D-5	1 (512)
MADRS	0.38 (512)	1
EQ-5D-5L	−0.45 (510)	−0.47	1
SDS	0.47 (437)	0.38	−0.57	1
DSST	−0.08 (512)	−0.14	0.12	−0.08	1
PHQ-9	0.63 (506)	0.53	−0.61	0.62	−0.09	1
(B) Month 1
Assessment		PDQ-D-5 (n)	MADRS	EQ-5D-5L	SDS	PHQ-9
PDQ-D-5		1 (404)
MADRS		0.46 (404)	1
EQ-5D-5L		−0.62 (403)	−0.53	1
SDS		0.54 (323)	0.57	−0.68	1
PHQ-9		0.67 (396)	0.68	−0.73	0.73	1
(C) Month 2
Assessment	PDQ-D-5 (n)	MADRS	EQ-5D-5L	SDS	DSST	PHQ-9
PDQ-D-5	1 (393)
MADRS	0.53 (393)	1
EQ-5D-5L	−0.66 (392)	−0.6	1
SDS	0.67 (309)	0.62	−0.73	1
DSST	−0.14 (391)	−0.25	0.23	−0.14	1
PHQ-9	0.75 (389)	0.67	−0.76	0.77	−0.2	1
(D) Month 6
Assessment	PDQ-D-5 (n)	MADRS	EQ-5D-5L	SDS	DSST	PHQ-9
PDQ-D-5	1 (336)
MADRS	0.61 (336)	1
EQ-5D-5L	−0.70 (336)	−0.65	1
SDS	0.71 (266)	0.65	−0.73	1
DSST	−0.27 (333)	−0.24	0.3	−0.28	1
PHQ-9	0.75 (331)	0.72	−0.81	0.82	−0.27	1
(E) Repeated Measures Correlation
Assessment			rmcorr (n)		p value
MADRS			0.60 (1645)		< 0.0001
EQ-5D-5L			−0.57 (1641)		< 0.0001
SDS			0.56 (1335)		< 0.0001
DSST			−0.37 (1237)		< 0.0001
PHQ-9			0.69 (1622)		< 0.0001

Notes: Parts A–D show Pearson correlation coefficients between PDQ-D-5, MADRS, EQ-5D-5L, SDS, DSST, and PHQ-9 scores, at baseline and over the 6 months following the initiation of antidepressant medication. Note that the DSST score was not measured at month 1. To integrate the longitudinal nature of the data, rmcorr was used to account for non-independence among repeated measures (Part E). A correlation coefficient with an absolute value > 0.7 indicates a strong correlation (green), while 0.4–0.7 (blue) or < 0.4 (white) indicates moderate and weak correlations, respectively. n is the number of observations used for each correlation. P values are statistically significant at the level of 0.001.

Abbreviations: DSST, Digit Symbol Substitution Test; EQ-5D-5L, EuroQol five-dimension, five-level quality of life questionnaire; MADRS, Montgomery–Asberg Depression Rating Scale; PHQ-9, Patient Health Questionnaire–nine-item; PDQ-D-5, Perceived Deficits Questionnaire for Depression–five-item; rmcorr, repeated measures correlation; SDS, Sheehan Disability Scale.