Comparing five depression measures in depressed Chinese patients using item response theory: an examination of item properties, measurement precision and score comparability

Table 2 Results from classical item analysis and unidimensionality analysis of BDI-II, CES-D, PHQ-9, DASS-Depression, and HADS-Depression

Scale^a	no ^b	M ^c	SD ^d	α^e	Item-Total Correlation		Exploratory Factor Analysis (EFA)			Confirmatory Factor Analysis (CFA)
Scale^a	no ^b	M ^c	SD ^d	α^e	Range	Mean	First eigenvalue	Second eigenvalue	Ratio^f	CFI^g	TLI^h	RMSEAⁱ
BDI-II	21	22.4	13.0	.92	.43 – .73	.59	9.49	1.10	8.63	0.95	0.94	0.075
CES-D	20	26.2	11.9	.92	.27 – .79	.59	9.30	1.04	8.94	0.94	0.93	0.093
PHQ-9	9	10.8	7.2	.91	.61 – .79	.68	5.59	0.37	15.11	0.97	0.97	0.117
DASS-Depression	7	15.5	11.2	.91	.58 – .80	.73	4.81	0.25	19.24	0.98	0.98	0.119
HADS-Depression	7	8.7	4.5	.82	.44 – .65	.57	3.42	0.29	11.79	0.98	0.97	0.093
All Items	64	-	-	.98	.21 – .81	.62	29.95	2.52	11.88	0.95	0.95	0.051
		Correlation (in lower triangle)/Disattentuated Correlations (in upper triangle)
		BDI-II			CES-D		PHQ-9		DASS-Depression		HADS-Depression
BDI-II		-			0.91		0.88		0.88		0.86
CES-D		0.84			-		0.93		0.91		0.86
PHQ-9		0.81			0.85		-		0.89		0.85
DASS-Depression		0.81			0.83		0.81		-		0.87
HADS-Depression		0.75			0.75		0.73		0.75		-

Note
^a BDI-II = Beck Depression Inventory–II. Raw scores range from 0 to 63; higher scores indicate more depressive symptoms
CES-D = Center for Epidemiologic Studies Depression Scale. Raw scores range from 0 to 60; higher scores indicate more depressive symptoms
PHQ-9 = Nine-item Patient Health Questionnaire. Raw scores range from 0 to 27; higher scores indicate more depressive symptoms
DASS-Depression = Depression subscale of the 21-item Depression, Anxiety and Stress Scale. Raw scores range from 0 to 21; higher scores indicate more depressive symptoms
HADS-Depression = Depression subscale of the Hospital Anxiety and Depression Scale. Raw scores range from 0 to 21; higher scores indicate more depressive symptoms
^b no = number of items
^c M = mean
^d SD = standard deviation
^e α = Cronbach’s alpha
^f Ratio = the ratio of the first eigenvalue to the second eigenvalue (Ratio > 4 supports unidimensionality)
^g CFI = comparative fit index (CFI > .90 indicates adequate fit; CFI > .95 indicates very good fit)
^h TLI = Tucker Lewis index (TLI > .90 indicates adequate fit; TLI > .95 indicates very good fit)
ⁱ RMSEA = root mean square error of approximation (RMSEA < .10 indicates adequate fit; RMSEA < .05 indicates very good fit)

ISSN: 1477-7525