Item response theory analysis of Centers for Disease Control and Prevention Health-Related Quality of Life (CDC HRQOL) items in adults with arthritis

Table 1 Observed Frequencies and recoding scheme for the HDCM and HDSM

Freq	HDCM 2	HDCM 3	HDCM 4	HDSM 1	HDSM 2	HDSM 3	HDSM 4	HDSM 5
0	339	588	761	469	580	456	327	654
1	45	56	43	49	80	66	26	32
2	91	123	82	97	136	131	87	68
3	86	83	55	71	95	102	72	56
4	67	44	41	51	44	52	50	35
5	123	128	98	91	129	147	109	124
6	25	21	15	17	19	24	29	16
7	43	38	33	28	37	35	38	26
8	26	13	18	14	20	12	25	17
9	7	4	6	6	5	2	4	5
10	143	137	106	120	137	142	157	138
11	0	1	3	2	5	1	0	1
12	13	12	10	13	11	9	26	9
13	1	3	4	3	2	2	2	4
14	24	13	17	10	7	11	14	6
15	141	117	99	103	106	118	134	126
16	5	2	3	0	2	2	2	4
17	3	1	3	1	1	3	3	1
18	11	4	5	8	4	5	6	6
19	1	1	1	0	0	0	2	3
20	155	113	105	133	93	106	165	98
21	10	4	2	6	3	1	9	7
22	5	3	3	1	3	8	4	3
23	2	1	1	5	2	1	5	8
24	3	4	5	3	0	1	1	6
25	54	50	54	64	47	45	95	91
26	4	2	5	4	4	2	2	13
27	5	3	2	8	5	2	3	18
28	15	16	6	14	6	14	15	44
29	4	6	3	2	4	4	1	12
30	315	177	185	385	177	264	366	107
Missing	54	52	46	42	56	52	41	82

HDCM items 2-4 = 4-item Healthy Days Core Module (HDCM 1: self-rated global health with five responses is not shown here), HDCM 2: Physical health not good, HDCM 3: Mental health not good, HDCM 4: Poor health; HDSM = 5-item Healthy Days Symptoms Module, HDSM 1: Pain limited activities, HDSM 2: Depressed, HDSM 3: Stress HDSM 4: Not enough rest, HDSM 5: Full of energy (reversed scored)

ISSN: 1477-7525