Development and Psychometric Properties of the Chronic Uveitis-Specific Quality of Life Instrument for Patients with Chronic Uveitis

Figures & data

Table 1. Characteristics of participants (n = 322).

Characteristic	N (%)	Scale score (logits)
		Symptoms	Visual Function	Concern about Disease and Treatment	Anxiety and Depression	Social Function
Gender
Female	166 (51.6%)	2.34 ± 0.92	2.19 ± 1.38	0.04 ± 1.93	2.47 ± 1.13	2.60 ± 1.47
Male	156 (48.4%)	2.19 ± 0.84	1.72 ± 1.43	0.02 ± 1.89	2.34 ± 1.24	2.07 ± 1.40
P value		0.052	0.002	0.860	0.275	<0.001
Age
≤ 30 years	57 (17.7%)	2.28 ± 1.02	2.11 ± 1.56	0.07 ± 1.89	2.42 ± 1.23	2.43 ± 1.41
30–50 years	201 (62.4%)	2.22 ± 0.86	1.90 ± 1.44	−0.04 ± 1.97	2.36 ± 1.18	2.21 ± 1.55
≥ 50 years	64 (19.9%)	2.40 ± 0.77	1.94 ± 1.15	0.19 ± 1.74	2.54 ± 1.18	2.64 ± 1.17
P value		0.404	0.434	0.586	0.608	0.178
Education
Primary and below	23 (7.1%)	2.12 ± 1.23	1.53 ± 1.58	0.72 ± 2.13	2.67 ± 1.59	2.43 ± 1.60
Middle and high school	155 (48.1%)	2.25 ± 0.80	1.78 ± 1.43	−0.07 ± 1.80	2.40 ± 1.17	2.27 ± 1.52
College and above	144 (44.7%)	2.31 ± 0.91	2.22 ± 1.35	0.02 ± 1.97	2.37 ± 1.14	2.40 ± 1.38
P value		0.513	0.018	0.266	0.510	0.656
Employment status
Employed	208 (64.6%)	2.29 ± 0.87	1.99 ± 1.41	−0.03 ± 1.86	2.34 ± 1.19	2.33 ± 1.48
Unemployed	37 (11.5%)	2.32 ± 0.82	1.90 ± 1.15	−0.05 ± 1.99	2.48 ± 1.08	2.36 ± 1.18
Retired	57 (17.7%)	2.46 ± 1.02	2.67 ± 1.33	0.91 ± 1.95	3.23 ± 1.13	2.96 ± 1.33
Student	20 (6.2%)	1.97 ± 0.93	1.47 ± 1.77	0.03 ± 1.95	2.21 ± 1.25	2.01 ± 1.75
P value		0.581	0.057	0.090	0.003	0.122
Laterality
Unilateral	109 (33.9%)	2.46 ± 0.85	2.65 ± 1.06	0.57 ± 2.01	2.76 ± 1.17	2.86 ± 1.28
Bilateral	213 (66.1%)	2.17 ± 0.89	1.60 ± 1.45	−0.25 ± 1.79	2.22 ± 1.16	2.07 ± 1.48
P value		0.003	<0.001	0.001	<0.001	<0.001
Anatomical location
Anterior uveitis	22 (6.8%)	2.26 ± 0.99	2.57 ± 1.09	0.82 ± 2.12	2.72 ± 1.22	2.83 ± 1.46
Intermediate uveitis	42 (13%)	2.69 ± 0.73	2.79 ± 1.08	0.38 ± 2.09	2.85 ± 1.24	2.89 ± 1.67
Posterior uveitis	50 (15.5%)	2.43 ± 0.85	2.24 ± 1.21	0.44 ± 1.61	2.83 ± 1.22	2.75 ± 1.17
Panuveitis	208 (64.6%)	2.14 ± 0.88	1.66 ± 1.47	−0.22 ± 1.87	2.18 ± 1.11	2.08 ± 1.42
P value		0.001	<0.001	0.010	<0.001	<0.001
LogMAR BCVA in the better eye
20/20–20/25	187 (58.1%)	2.68 ± 0.67	2.89 ± 0.85	0.70 ± 1.77	2.84 ± 1.09	2.97 ± 1.11
20/32–20/50	109 (33.9%)	1.77 ± 0.72	1.01 ± 0.64	−0.77 ± 1.70	1.91 ± 1.04	1.57 ± 1.34
≥20/63	26 (8.1%)	1.38 ± 1.15	−0.74 ± 0.96	−1.44 ± 1.50	1.31 ± 0.89	1.05 ± 1.84
P value		<0.001	<0.001	<0.001	<0.001	<0.001
LogMAR BCVA in the worse eye
20/20–20/25	107 (33.2%)	2.83 ± 0.66	3.29 ± 0.62	0.88 ± 1.85	2.97 ± 1.17	3.16 ± 1.15
20/32–20/50	159 (49.4%)	2.11 ± 0.74	1.69 ± 0.92	−0.17 ± 1.78	2.27 ± 1.04	2.13 ± 1.30
≥20/63	56 (17.4%)	1.62 ± 1.01	0.19 ± 1.33	−1.03 ± 1.68	1.70 ± 1.14	1.37 ± 1.65
P value		<0.001	<0.001	<0.001	<0.001	<0.001
Activity status
Active	36 (11.2%)	1.87 ± 1.01	0.80 ± 1.62	−1.26 ± 1.59	1.59 ± 0.99	1.57 ± 1.48
Inactive	286 (88.8%)	2.32 ± 0.86	2.10 ± 1.33	0.19 ± 1.88	2.51 ± 1.17	2.44 ± 1.43
P value		0.005	<0.001	<0.001	<0.001	<0.001
Relapse
Yes	131 (40.7%)	2.18 ± 0.92	1.75 ± 1.52	−0.37 ± 1.86	2.19 ± 1.16	2.14 ± 1.57
No	191 (59.3%)	2.33 ± 0.86	2.10 ± 1.34	0.31 ± 1.89	2.55 ± 1.19	2.48 ± 1.37
P value		0.131	0.061	0.001	0.009	0.057
Ocular complications
Yes	112 (34.8%)	2.08 ± 0.75	1.56 ± 1.42	−0.35 ± 1.86	2.10 ± 1.13	1.84 ± 1.47
No	210 (65.2%)	2.37 ± 0.94	2.17 ± 1.38	0.23 ± 1.90	2.57 ± 1.19	2.61 ± 1.39
P value		0.001	<0.001	0.012	0.001	<0.001

*Data are presented as mean ± SD. Wilcoxon rank sum test, p-values below 0.05 are bolded. BCVA, best-corrected visual acuity; SD, standard deviation

Table 2. Exploratory factor analysis of the Chronic Uveitis-Related Quality of Life Questionnaire version 1.0 (CUQOL 1.0).

Items	Factor 1 Symptoms	Factor 2 Visual Function	Factor 3 Concern about Disease and Treatment	Factor 4 Anxiety and Depression	Factor 5 Social Function
Q1	0.25	0.12	−0.02	0.07	0.78
Q2	0.16	0.05	0.21	0.07	0.75
Q3	0.18	0.09	0.12	0.31	0.68
Q4	0.54	0.15	0.08	0.06	0.45
Q5	0.29	0.21	0.05	0.04	0.56
Q6	0.80	0.10	0.13	0.24	0.13
Q7	0.73	0.14	0.17	0.20	0.19
Q8	0.80	0.11	0.11	0.17	0.16
Q9	0.83	0.16	0.12	0.11	0.13
Q10	0.72	0.21	0.07	0.11	0.23
Q11	0.70	0.09	0.15	0.26	0.23
Q12	0.72	0.05	0.16	0.40	0.10
Q13	0.19	0.42	0.72	0.11	0.09
Q14	0.08	0.26	0.78	0.03	0.12
Q15	0.16	0.21	0.82	0.23	0.06
Q16	0.23	0.22	0.76	0.30	0.06
Q17	0.15	0.25	0.78	0.21	0.13
Q18	0.09	0.68	0.31	0.14	0.09
Q19	0.10	0.74	0.27	0.13	0.12
Q20	0.07	0.64	0.23	0.21	0.18
Q21	0.12	0.76	0.13	0.25	0.16
Q22	0.22	0.67	0.24	0.28	0.06
Q23	0.21	0.72	0.16	0.18	0.04
Q24	0.24	0.28	0.19	0.73	0.08
Q25	0.17	0.23	0.18	0.70	0.13
Q26	0.29	0.24	0.17	0.71	0.17
Q27	0.24	0.14	0.21	0.76	0.09
Q28	0.24	0.29	0.07	0.62	0.09
Explained variance (%)	18.14	13.74	12.96	12.24	9.14
Cumulative variance (%)	18.14	31.88	44.83	57.07	66.21

Extraction method: principal component analysis; Rotation method: Varimax with Kaiser Normalization

The factor loading for each item in its dimensions is indicated in bold.

Figure 1. (a) Category probability curves (CPC) of five response categories for Symptoms subscale. (b) CPC for Visual Function subscale. (c) CPC for Concern about Disease and Treatment subscale. (d) CPC for Emotional subscale. (e) CPC for Social function subscale.

Table 3. Dimensionality and Local Dependence Analysis of the subscales of the Chronic Uveitis-Related Quality of Life Questionnaire version 1.0 (CUQOL 1.0).

	Symptoms subscale		Visual Function subscale		Concern about Disease and Treatment subscale		Emotional subscale		Social function subscale
	Eigen	%	Eigen	%	Eigen	%	Eigen	%	Eigen	%
Total raw variance	10.1	100.0	20.7	100.0	15.6	100.0	14.0	100.0	13.5	100.0
Explained by measures	5.1	50.4	13.7	66.1	10.6	68.0	8.0	57.2	8.5	63.0
Explained by persons	4.6	45.6	11.5	55.8	10.6	67.6	7.1	50.3	7.5	55.7
Explained by items	0.5	4.8	2.1	10.3	0.1	0.4	1.0	7.0	1.0	7.3
Total unexplained	5.0	49.6	7.0	33.9	5.0	32.0	6.0	42.8	5.0	37.0
1st contrast	1.9	18.5	1.8	8.8	1.9	12	1.8	12.7	1.5	11.4
2st contrast	1.1	11.2	1.3	6.3	1.3	8.0	1.4	10.0	1.3	9.7
3st contrast	1.0	9.7	1.3	6.1	0.8	5.1	1.1	8.0	1.1	8.3
4st contrast	0.0	0.0	1.0	5.0	0.0	0.0	1.0	6.9	1.0	7.5
5st contrast	0.0	0.0	0.8	4.1	0.0	0.0	0.7	5.1	0.0	0.0
	Correlation	Item Item	Correlation	Item Item	Correlation	Item Item	Correlation	Item Item	Correlation	Item Item
	0.43	Q3 Q4	0.32	Q7 Q12	0.07	Q13 Q14	0.21	Q22 Q23	0.37	Q25 Q28
	0.41	Q3 Q5	0.30	Q6 Q7	0.01	Q15 Q16	0.43	Q18 Q23	0.33	Q24 Q26
	0.39	Q2 Q4	0.28	Q6 Q10	0.49	Q13 Q15	0.38	Q21 Q22	0.33	Q24 Q28
	0.38	Q2 Q5	0.28	Q8 Q12	0.43	Q14 Q16	0.34	Q19 Q20	0.32	Q27 Q28
	0.34	Q1 Q4	0.25	Q10 Q12	0.39	Q14 Q17	0.29	Q18 Q22	0.30	Q25 Q26
	0.30	Q1 Q5	0.24	Q7 Q9	0.34	Q13 Q16	0.27	Q20 Q23	0.26	Q24 Q27
	0.13	Q1 Q3	0.24	Q6 Q9	0.34	Q14 Q15	0.26	Q20 Q22	0.19	Q26 Q28
	0.02	Q1 Q2	0.24	Q10 Q11	0.25	Q13 Q17	0.23	Q19 Q22	0.17	Q26 Q27
	0.02	Q4 Q5	0.23	Q9 Q11	0.24	Q16 Q17	0.21	Q19 Q23	0.11	Q25 Q27
	0.02	Q2 Q3	0.22	Q8 Q11	0.11	Q15 Q17	0.19	Q21 Q23	0.07	Q24 Q25

Table 4. Summary of psychometric analysis of the Chronic Uveitis-Related Quality of Life Questionnaire version 1.0 (CUQOL 1.0).

Scales	No. of Items	Classical Test Theory							Rasch Analysis
		Missing Data (%)	Floor effects (%)	Ceiling effects (%)	Item-total score correlations	Cronbach’s Alpha(n = 322)	Test-Retest (ICC)(n = 158)		Location(logits)	Infit MNSQ	OutfitMNSQ	DIF contrastby ender	PSI
Symptoms subscale
Eye redness	1	1.6	0.3	39.4	0.42*	0.75	0.95**		−0.49	0.76	0.89	0.00	1.40
Ocular pain	2	0.9	0.0	39.2	0.46*				−0.46	0.84	0.85	0.50
Photophobia	3	1.2	1.3	29.9	0.55*				0.39	1.04	1.01	0.80
Blurred vision	4	0.0	1.2	31.7	0.57*				0.6	1.08	1.07	0.21
Floaters	5	2.8	1.6	38.3	0.47*				−0.04	1.16	1.15	0.25
Visual Function subscale
Difficulty reading messages on the screen of your electronic device	6	0.0	2.5	35.1	0.67**	0.91	0.97**		0.24	0.95	0.92	0.16	2.53
Difficulty reading street signs or store signages	7	0.0	0.9	28	0.67**				0.01	0.96	1.03	0.35
Difficulty noticing objects off to the side while walking	8	1.6	1.3	46.4	0.65**				−0.92	0.97	0.81	0.14
Difficulty crossing a road while traffic is flowing	9	1.6	0.6	42.9	0.64**				0.35	0.33	1.29	0.12
Difficulty doing household chores	10	0.9	3.1	29.2	0.59**				−1.29	0.65	0.64	0.13
Difficulty driving (bicycle or car) in a familiar street during daytime	11	2.5	6.7	33.8	0.67**				0.39	0.32	1.28	0.19
Difficulty completing your work or other activities	12	0.0	4.3	13	0.67**				1.22	0.79	0.80	0.12
Concern about Disease and Treatment subscale
Being distressed by the lengthy treatment process	13	0.0	7.8	10.6	0.69**	0.91	0.98**		−0.16	0.90	0.93	0.21	2.46
Being concerned about the side effects of long-term medication	14	0.9	8.2	10	0.57**				−0.05	1.16	1.13	0.51
Being worried about developing uveitis complications	15	0.0	10.9	12.1	0.68**				0.09	0.89	0.86	0.0
Being afraid of losing your vision	16	0.0	9.3	13.7	0.70**				−0.11	1.02	1.02	0.76
Getting upset about recurrent relapses of disease	17	0.0	13.4	12.7	0.69**				0.23	1.00	0.97	0.04
Emotional subscale									0.28
Being irritable, impatient, or less tolerant	18	1.9	0.3	25	0.60**	0.87	0.96**			1.01	1.03	0.39	1.98
Worrying thoughts go through your mind	19	0	0.6	23	0.61**				0.73	1.00	1.00	0.00
Trouble falling asleep, staying asleep, or sleeping too much	20	1.6	0.0	37.2	0.58**				−0.37	1.19	1.19	0.42
Feeling down, depressed, or hopeless	21	0.0	0.3	24.5	0.64**				0.42	0.84	0.84	0.04
Thought all bad things happened to you	22	0.6	0.0	36.6	0.68**				−0.29	1.00	1.01	0.45
Lowering expectations for your present life	23	1.9	0.3	39.6	0.61**				−0.77	0.92	0.89	0.31
Social function subscale
Avoided going out of the house to visit friends or relatives, or attending other social activities	24	0.0	2.2	37.3	0.69**	0.86	0.97**		0.81	1.07	0.99	0.13	1.98
Affecting your romantic relationships or marriage	25	2.8	1.0	39.6	0.60**				0.80	0.99	0.98	0.51
Affecting your professional role, career advancement, or choices	26	3.4	1.0	36	0.64**				−0.04	0.86	0.87	0.11
Changed your role in routine family activities	27	0.9	2.8	19.1	0.68**				−0.62	0.94	0.90	0.09
Caused a heavy economic burden for your family	28	1.9	1.6	18	0.59**				−0.96	1.13	1.16	0.33

ICC, intraclass correlation coefficient; DIF, Differential item functioning; PSI, person separation index; MNSQ, mean square.

*Represents p value < 0.05, **Represents p value < 0.01, Spearman’s rank correlation.

Table 5. Correlations between the Chronic Uveitis-Related Quality of Life Questionnaire version 1.0 (CUQOL 1.0) scores and the National Eye Institute Visual Function Questionnaire (NEI-VFQ-25).

	NEI-VFQ-25
CUQOL 1.0 Subscale/Total Score	LFVFS25	LFSES25
Symptoms	0.50*	0.43*
Visual Function	0.82*	0.73*
Concern about Disease and Treatment	0.43*	0.41*
Anxiety and Depression	0.43*	0.44*
Social Function	0.51*	0.65*

LFVFS 25: long-form visual functioning scale derived from NEI-VFQ-25

LFSES 25: long-form socioemotional scale derived from NEI-VFQ-25

*Represents p value < 0.01, Spearman rank’s correlation.

Table 6. Responsiveness of the Chronic Uveitis-Related Quality of Life Questionnaire version 1.0 (CUQOL 1.0) in 107 patients.

Variables	Occasion 1	Occasion 2	P value
The CUQOL 1.0 score (logits), mean (SD)
Symptoms	2.19(0.94)	2.60(0.68)	<.001
Visual Function	1.89(1.42)	2.67(1.13)	<.001
Concern about Disease and Treatment	−0.11(1.90)	0.36(1.70)	<.001
Anxiety and Depression	2.44(1.25)	2.65(1.13)	<.001
Social Function	2.27(1.56)	2.47(1.39)	.018
LogMAR BCVA, mean (SD)
Better-seeing eye	0.3(0.3)	0.2(0.2)	<.001
Worse-seeing eye	0.2(0.2)	0.1(0.1)	<.001

BCVA, best-corrected visual acuity; SD standard deviation

Occasion 1: the first survey; Occasion 2: six months after the first survey.