Validation of the Chinese version of the PHQ-15 in a tertiary hospital

BMC Psychiatry

Table 6 Thresholds for the three possible factors of the PHQ-15 based on IRT analysis

	Diff.	Coef.	Std. Err.	z	P > z	[95 % Conf.	Interval]
Factor 1
Item 2	1 vs 0	0.351	0.064	5.49	<0.001	0.226	0.477
	2 vs 1	2.094	0.114	18.31	<0.001	1.870	2.318
Item 3	1 vs 0	0.320	0.065	4.92	<0.001	0.193	0.448
	2 vs 1	1.577	0.095	16.52	<0.001	1.390	1.764
Item 4	1 vs 0	2.590	0.126	20.50	<0.001	2.342	2.838
	2 vs 1	2.685	0.237	11.32	<0.001	2.220	3.150
Item 5	1 vs 0	0.792	0.068	11.58	<0.001	0.658	0.926
	2 vs 1	2.567	0.145	17.71	<0.001	2.282	2.851
Item 6	1 vs 0	0.734	0.068	10.85	<0.001	0.602	0.867
	2 vs 1	2.427	0.136	17.83	<0.001	2.160	2.693
Item 7	1 vs 0	0.385	0.064	6.09	<0.001	0.261	0.509
	2 vs 1	2.684	0.144	18.61	<0.001	2.401	2.966
Item 8	1 vs 0	1.910	0.099	19.38	<0.001	1.716	2.103
	2 vs 1	2.277	0.164	13.90	<0.001	1.956	2.598
Item 11	1 vs 0	1.849	0.096	19.19	<0.001	1.661	2.038
	2 vs 1	2.292	0.162	14.14	<0.001	1.975	2.610
Factor 2
Item 9	1 vs 0	0.366	0.040	9.16	<0.001	0.288	0.445
	2 vs 1	1.872	0.080	23.43	<0.001	1.715	2.029
Item 10	1 vs 0	0.558	0.042	13.18	<0.001	0.475	0.641
	2 vs 1	1.641	0.070	23.30	<0.001	1.503	1.779
Factor 3
Item 1	1 vs 0	0.867	0.063	13.80	<0.001	0.745	0.992
	2 vs 1	2.052	0.112	18.37	<0.001	1.833	2.271
Item 12	1 vs 0	0.122	0.055	2.21	0.027	0.014	0.230
	2 vs 1	1.737	0.089	19.42	<0.001	1.561	1.912
Item 13	1 vs 0	0.152	0.055	2.76	0.006	0.044	0.260
	2 vs 1	1.831	0.093	19.67	<0.001	1.649	2.014
Item 14	1 vs 0	−0.469	0.057	−8.18	<0.001	−0.581	−0.357
	2 vs 1	1.598	0.081	19.64	<0.001	1.439	1.758
Item 15	1 vs 0	−0.118	0.056	−2.10	0.035	−0.228	0.008
	2 vs 1	1.329	0.075	17.62	<0.001	1.181	1.477

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