Psychometric properties of the Anxiety Inventory for Respiratory Disease in patients with COPD in China

Figures & data

Table 1 COPD patients’ characteristics (N=181)

Characteristics	n	%/mean (SD)
Age (years)	181	67.21 (8.1)
Gender
Female	59	32.6
Male	122	67.4
Body mass index (kg/m^2)	181	23.89 (4.08)
Comorbidities
None	57	31.5
1	69	38.1
≥2	55	30.4
Smoking status
Never	44	24.3
Ex-smoker	114	63.0
Current smoker	23	12.7
MRC dyspnea scale
0	14	7.7
1	22	12.2
2	72	39.8
3	50	27.6
4	23	12.7
Frequency of exacerbations in the last year
0	39	21.5
1	70	38.7
2	43	23.8
≥3	29	16
Grades of COPD	150
GOLD 1	4	2.67
GOLD 2	52	34.67
GOLD 3	64	42.68
GOLD 4	30	19.98
Total score of AIR	181	7.15 (3–11)
Total score of CCQ	181	2.53 (0.86)
Total score of HADS	181	12.56 (7.89)
HADS-A		4.83 (3.88)
HADS-D		7.73 (4.62)
Total score of ADLS	181	21.65 (14.5–25)
Somatic dimension		7.7 (6–8)
Instrument dimension		13.95 (8.5–17)

Notes: Continuous variables are expressed as mean (standard deviation) or median (first and third quartiles Q1–Q3), and categorical variables are expressed as relative frequencies and proportion.

Abbreviations: MRC, Medical Research Council; GOLD, Global Initiative for Chronic Obstructive Lung Disease; AIR, Anxiety Inventory for Respiratory Disease; CCQ, Clinical COPD Questionnaire; HADS, Hospital Anxiety and Depression Scale; A, anxiety; D, depression; ADLS, Activities of Daily Living Scale.

Table 2 Experts’ ratings and CVI calculation (n=9)

Item	Experts’ ratingsa									I-CVIb
	A	B	C	D	E	F	G	H	I
H1	4	3	3	4	3	4	4	3	3	1
H2	4	4	4	4	4	4	4	4	4	1
H3	4	4	4	4	4	4	4	4	4	1
H4	4	4	4	4	4	4	3	3	4	1
H5	4	4	3	2	3	4	3	3	4	0.89
H6	3	4	4	4	4	4	4	4	4	1
H7	4	4	4	4	4	4	4	4	4	1
H8	4	4	4	4	4	4	4	4	4	1
H9	4	4	4	4	4	4	4	4	4	1
H10	3	4	4	4	4	4	4	4	4	1

Notes:

a Nine expert ratings for the 10-item AIR scale.

b According to the criteria for I-CVI, a scale with an I-CVI value ≥0.78 was considered acceptable.

Abbreviations: CVI, content validity index; I-CVI, item-level CVI; AIR, Anxiety Inventory for Respiratory Disease.

Table 3 Spearman’s ρ correlations of AIR with other measures

Measure	AIR total
HADS-Total	0.83
HADS-A	0.81*
HADS-D	0.76
ADLS	0.36*
CCQ	0.44*

Note:

* Correlation is significant at the 0.05 level.

Abbreviations: AIR, Anxiety Inventory for Respiratory Disease; HADS, Hospital Anxiety and Depression Scale; HADS-A, Hospital Anxiety and Depression Scale-Anxiety; HADS-D, Hospital Anxiety and Depression Scale-Depression; ADLS, Activities of Daily Living Scale; CCQ, Clinical COPD Questionnaire.

Table 4 Model fit indices for the four models of the AIR-C scale

Model	TLI	GFI	IFI	CFI	RMSEA	RMR
Model 1	0.92	0.90	0.94	0.94	0.1	0.02
Model 2	0.92	0.90	0.94	0.94	0.09	0.02
Model 3	0.95	0.93	0.97	0.97	0.07	0.01

Abbreviations: TLI, Tucker–Lewis Index; GFI, Goodness-of-Fit Index; IFI, Incremental Fit Index; CFI, Comparative Fit Index; RMSEA, root mean square error of approximation; RMR, root mean square residual; AIR-C, Anxiety Inventory for Respiratory Disease-Chinese version.

Figure 1 Model 1, two-factor model.

Note: Item 10 belongs to both the Panic and the GenAnx.

Abbreviation: GenAnx, general anxiety.

Figure 2 Model 2 and Model 3, modified two-factor models for AIR-C.

Notes: (A) Model 2, two-factor model. Item 10 belongs to the GenAnx. (B) Model 3, modified two-factor models (model 2) for AIR, allowing error terms in items 3 and 7, 6 and 10, and 3 and 10 to covary.
Abbreviations: AIR-C, Anxiety Inventory for Respiratory Disease-Chinese version; GenAnx, generalized anxiety.