Development and preliminary validation of a self-rating anxiety inventory for maintenance haemodialysis patients

Figures & data

Table 1. Sociodemographic and clinical characteristics of the participants.

	I-AI-MHD participants			AI-MHD participants
	Anxiety disorders group (n = 33)	Non-anxiety disorders group (n = 64)	p	Anxiety disorders (n = 92)	Non-anxiety disorders group (n = 218)	p
Age (years)	55.09 ± 15.72	54.6 ± 14.43	0.898	53.45 ± 10.04	53.02 ± 11.24	0.612
Gender (N%)			0.226			0.117
Male	10(30.3)	29(45.31)		31(33.69)	96(44.04)
Female	23(69.7)	35(54.69)		61(66.31)	122(55.96)
BMI (W/H^2)	23.78 ± 5.57	21.23 ± 6.32	0.423	23.31 ± 6.78	21.74 ± 7.16	0.532
Length of dialysis (months)	54.36 ± 17.23	51.4 ± 19.19	0.362	50.67 ± 19.62	48.23 ± 19.92	0.135
Employment status (N%)			0.288			0.298
Working	4(12.12)	15(23.43)		14(15.22)	46(21.10)
Not working	29(87.88)	49(76.57)		78(84.78)	172(78.90)
Income status (N%)			0.413			0.613
<2000 Yuan/month	12(36.36)	26(40.62)		33(51.56)	66(30.28)
2000–4000 Yuan/month	17(51.52)	28(43.75)		41(44.57)	100(45.87)
>4000 Yuan/month	4(12.12)	10(15.63)		18(19.57)	52(23.85)
Education level (N%)			0.872			0.748
Primary and secondary school	5(15.15)	8(12.50)		14(15.22)	31(14.22)
High school degree or equivalent	13(39.40)	25(39.06)		35(38.04)	83(38.07)
College degree or above	15(45.45)	31(48.44)		43(46.74)	104(47.71)
ADL (N%)			0.324			0.365
I	18(54.55)	33(51.56)		42(45.65)	134(61.47)
II	11(33.33)	24(37.50)		36(39.13)	66(30.27)
III	2(6.06)	3(4.69)		8(8.69)	12(5.50)
IV	2(6.06)	4(6.25)		6(6.52)	6(2.76)

I-AI-MHD: initial anxiety inventory for MHD patients; AI-MHD: anxiety inventory for MHD patients; BMI: body mass index; ADL: activity of daily living; N: number of participants. The p value represents the comparison between patients with anxiety disorders and patients with non-anxiety disorders. The t-test was used to compare continuous variables; chi-square analysis was used to compare categorical variables. Unless otherwise stated, data are expressed as the mean ± standard deviation.

Table 2. Comparison of I-AI-MHD scores for patients with anxiety and with non-anxiety disorders.

	Item	Anxiety disorders group (n = 33)	Non-anxiety disorders group (n = 64)	p
Item 1	Is it difficult to concentrate?	2.11 ± 0.41	0.91 ± 0.39	<0.001
Item 2	Do you easily feel nervous or anxious or suffering?	2.12 ± 0.75	0.89 ± 0.36	<0.001
Item 3	Are you nervous, afraid or scared of needles?	2.05 ± 1.04	0.93 ± 0.42	<0.001
Item 4	Are you nervous, afraid or scared of dialysis treatment?	1.91 ± 0.66	0.63 ± 0.33	<0.001
Item 5	Do you worry about the disease/dialysis treatment affecting your own work?	0.42 ± 0.75	0.32 ± 1.42	0.326
Item 6	Do you worry about dialysis burdening the family economy?	1.65 ± 0.71	0.73 ± 0.28	0.001
Item 7	Do you worry about dialysis affecting your ability to interact with others?	1.93 ± 0.78	0.92 ± 0.64	0.018
Item 8	Are you worried that your illness will worsen or aggravate at any time?	1.73 ± 0.23	0.55 ± 0.25	<0.001
Item 9	Do you feel as though your mind is restless?	1.96 ± 0.75	0.86 ± 0.48	0.015
Item 10	Do you feel scared for no reason?	2.05 ± 0.97	0.81 ± 0.53	0.019
Item 11	Are you worried that you might lose control or crash?	1.85 ± 0.44	0.76 ± 0.21	<0.001
Item 12	Are you afraid that medical personnel or family members cannot provide you good treatment or care?	2.31 ± 0.58	1.67 ± 0.67	0.088
Item 13	Do you feel fidgety?	2.06 ± 0.89	1.61 ± 0.72	0.235
Item 14	Do you feel as though it is very difficult to relax?	2.07 ± 1.02	0.75 ± 0.34	<0.001
Item 15	Do you feel you are impatient and lose your temper with others around you?	1.95 ± 0.55	0.65 ± 0.31	<0.001

bold indicates that the item was deleted. The p value represents the comparison between anxiety disorder patients and non-anxiety disorder patients using the Mann-Whitney U test. Data are expressed as the mean ± standard deviation.

Table 3. Analysis of the final 12-item AI-MHD.

	Item	Factor load	Corrected item-total correlation	Mean value (SD)
Item 1	Is it difficult to concentrate?	0.70	0.65	1.31 ± 0.35
Item 2	Do you easily feel nervous or anxious or suffering?	0.72	0.68	1.29 ± 0.36
Item 3	Are you nervous, afraid or scared of needles?	0.67	0.61	1.30 ± 0.41
Item 4	Are you nervous, afraid or scared about dialysis treatment?	0.65	0.60	1.07 ± 0.32
Item 5	Do you worry about dialysis burdening the family economy?	0.63	0.59	1.04 ± 0.34
Item 6	Do you worry about dialysis affecting your ability to interact with others?	0.60	0.55	1.27 ± 0.47
Item 7	Are you worried that your illness will worsen or aggravate at any time?	0.58	0.54	0.94 ± 0.19
Item 8	Do you feel as though your mind is restless?	0.62	0.58	1.23 ± 0.56
Item 9	Do you feel scared for no reason	0.69	0.64	1.22 ± 0.59
Item 10	Are you worried that you might lose control or crash?	0.57	0.53	1.12 ± 0.36
Item 11	Do you feel as though it is very difficult to relax?	0.68	0.63	1.19 ± 0.60
Item 12	Do you feel as though you are impatient and lose your temper with others around you?	0.66	0.61	1.08 ± 0.39

Table 4. Comparison of GAD-7, HADS-A, and AI-MHD mean values for patients with anxiety disorders and non-anxiety disorders.

	Anxiety disorders group (n = 92)	Non-anxiety disorders group (n = 218)	p
GAD-7	8.03 ± 3.10	3.15 ± 0.81	<0.001
HADS-A	7.05 ± 2.62	2.85 ± 0.89	<0.001
AI-MHD	23.24 ± 4.78	9.28 ± 2.89	<0.001

the t-test was used to compare the scores for patients with anxiety disorders and non-anxiety disorders. Data are expressed as the mean ± standard deviation.

Table 5. Correlation analysis of AI-MHD scores and GAD-7 and HADS-A scores.

	AI-MHD Kappa value	p
GAD-7	0.879	<0.001
HADS-A	0.698	<0.001

McNemar’s test was used for the comparison.

Table 6. Exploratory factor analysis of the promax rotation of the AI-MHD scale.

	Factor Load
	F1	F2	F3
Item 3	0.768	0.141	0.126
Item 4	0.737	0.167	0.127
Item 5	0.699	0.326	0.016
Item 6	0.673	0.386	−0.117
Item 2	0.013	0.892	0.075
Item 9	−0.128	0.778	0.059
Item 12	0.065	0.694	0.299
Item 7	0.370	0.592	0.229
Item 1	0.081	0.079	0.883
Item 11	−0.140	0.099	0.719
Item 8	0.027	0.329	0.697
Item 10	0.151	0.391	0.573

bold indicates the highest load coefficient. F1: disease related; F2: affective; F3: physical.

Table 7. Correlation analysis of AI-MHD subscale scores.

	F1	F2	F3
F1	1	0.735**	0.799**
F2		1	0.723**
F3			1

Pearson correlation was used to analyse the correlation among AI-MHD subscale scores.

F1: Disease related; F2: Affective; F3: Physical

(Physical) ** p ≤ 0.01.

Table 8. Cut-off values for the AI-MHD, GAD-7, and HADS-A.

	Cut-off Score	Sensitivity	Specificity	Youden index	PV,%	NPV,%
AI-MHD
	20.00	0.97	0.57	0.45	0.81	0.91
	21.00	0.96	0.71	0.60	0.86	0.90
	22.00	0.94	0.82	0.74	0.91	0.93
	23.00	0.93	0.90	0.89	0.93	0.95
	24.00	0.90	0.91	0.86	0.96	0.87
	25.00	0.86	0.93	0.71	0.92	0.72
	26.00	0.79	0.95	0.63	0.90	0.57
GAD-7
	5.00	0.92	0.60	0.55	0.49	0.95
	6.00	0.90	0.70	0.62	0.62	0.94
	7.00	0.88	0.75	0.67	0.76	0.93
	8.00	0.86	0.86	0.75	0.82	0.92
	9.00	0.79	0.92	0.77	0.87	0.90
	10.00	0.61	0.95	0.61	0.89	0.85
	11.00	0.45	0.97	0.44	0.92	0.72
HADS-A
	4.00	0.92	0.46	0.37	0.41	0.93
	5.00	0.89	0.61	0.48	0.53	0.95
	6.00	0.87	0.75	0.59	0.67	0.93
	7.00	0.83	0.87	0.68	0.79	0.91
	8.00	0.74	0.92	0.66	0.83	0.89
	9.00	0.61	0.94	0.49	0.87	0.85
	10.00	0.45	0.98	0.30	0.90	0.79

bold indicates the best cut-off point for each scale. NPV = negative predictive value; PPV = positive predictive value.

Figure 1. ROC curve for the AI-MHD, GAD-7, and HADS-A. Note: ROC: receiver operating characteristic; AUC: area under the curve; CI: confidence interval.