Depression and anxiety in patients with rheumatoid arthritis: prevalence rates based on a comparison of the Depression, Anxiety and Stress Scale (DASS) and the hospital, Anxiety and Depression Scale (HADS)

Table 3 Fit of the DASS and HADS items and all subscales (testlets) to the Rasch model

Analysis	Subscale	Item Fit Residual		Person Fit Residual		Chi-Square Interaction			PSI	Uni-dimensionality
		Mean	SD	Mean	SD	Value	DF	P		% tests	CI
Depression
8	DASS-D	-0.396	1.541	-0.431	1.244	49.69	28	0.007	0.945	6.59	3.3-9.9
9	DASS-D	-0.276	1.567	-0.354	1.132	39.34	22	0.013	0.940	4.79	1.5-8.1
10	HADS-D	-0.263	0.872	-0.382	0.899	25.16	28	0.619	0.856	3.01	0.0-6.3
Depression Combined
11	D+H-D	-0.560	1.422	-0.442	1.133	68.82	42	0.005	0.920	12.05	8.7-15.4
12	D+H-D	-0.423	1.248	-0.373	1.084	57.31	34	0.007	0.912	7.23	3.9-10.5
Stress
13	DASS-S	-0.025	1.383	-0.425	1.575	41.18	28	0.052	0.949	7.19	3.9-10.5
All Scales combined as testlets
14	All	-0.400	0.729	-0.353	0.842	10.73	10	0.378	0.900	2.52	0.0-5.9
15	All	-0.123	0.749	-0.378	0.968	10.12	10	0.430	0.870	2.00	-1.5-5.5
Ideal Fit		0.0	1.0	0.0	1.0			> 0.05*	> 0.7	< 5.0	Lower CI below 5

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