The Fear of Asthma Symptoms Scale and the Asthma Behavior Checklist: preliminary validity of two novel patient reported outcome measures

Figures & data

Table 1. The fear of asthma symptoms scale (FAS) with the initial 12 items.

FAS Below you find statements that describe how some people may feel about symptoms related to asthma. Symptoms of asthma may include shortness of breath, cough, wheezing or pressure in the chest. Specify how much you agree or disagree with each statement (0 = Do not agree at all, 5 = Very much agree). I worry that I will feel symptoms of asthma when I leave home. I get worried if I visit a place I have not been to before. I often worry about asthma. I have a hard time having fun because I can’t stop thinking about my asthma symptoms. I am often afraid that I will not be able to have a normal lung function. As soon as I sense symptoms of asthma, I get worried and anxious. I am constantly aware of my breathing. I often think about that asthma is a serious disease. As soon as I wake up, I start to worry that I will have trouble with my asthma during the day. When I feel stressed, I get worried about asthma. I keep thinking about what’s going on with my breathing. When I sense symptoms of asthma, I get anxious.

Table 2. The Avoidance Behavior Checklist (ABC) with the initial 29 items.

ABC Here is a list of common behaviors that many people with asthma do to reduce or avoid asthma symptoms. Indicate how well each statement below is true for you, from 1(Never) to 7 (Always). I prefer not taking the stairs I avoid hurrying I avoid exercise or physical strain I exercise, but less vigorous than I wish to I prefer not to take the bus or the subway when I feel symptoms of asthma. Whenever I can, I avoid crowds I take the stairs, but avoid walking fast or running I try to do calm breathing I often check my breathing I try not to cough out of fear of not being able to stop When I'm with people I do not know very well, I try not to laugh out of fear that it will turn into a cough I avoid taking walks I go for walks, but preferably not with others I avoid going to the cinema / theater / concerts / lectures I go to the cinema / theater / concerts / lectures but prefer to place myself so that I can easily leave the room. When I feel symptoms of asthma, I prefer not to talk in meetings or in other similar contexts. I deliberately breathe through my nose to control my asthma I make sure to breathe through a scarf or other face protection when the weather is cold. I think about taking it easy when I am with children, grandchildren or pets. I do not play wild or strenuous games with children, grandchildren or pets. I avoid becoming short of breath I try to do things as calmly as I can I bring a water bottle or throat tablets I plan my route so I will not have to walk I rest before activities I avoid having sex I hold back, not to exert myself too much I prefer not to travel long distances by train, airplane, or bus I avoid being far from available healthcare

Table 3. Sample characteristics (N = 188).

	N (%)
Female	156 (83%)
Age, mean (SD)	39.4 (15.75)
Education
High school	82 (44%)
University	79 (42%)
Other^a	27 (14%)
Employment^b
Full time	69 (37%)
Part time	44 (23%)
Student	47 (25%)
Retired	26 (14%)
Unemployed	16 (9%)
Asthma^c
Duration years, Mean (SD)	18.61 (14.12)
Controlled asthma (ACT ≥ 20)	67 (36%)
Partially controlled asthma (ACT 16-19)	61 (33%)
Uncontrolled asthma (ACT ≤15)	58 (31%)
Psychiatric diagnoses
Depression	74 (39%)
Anxiety disorder	55 (29%)
Other^d	45 (24%)
Chronic somatic syndromes
Allergies	150 (92%)
Eczema	53 (28%)
Auto-immune disease^e	23 (12%)
Pain disorders^f	35 (18%)

a Elementary School, Vocational School, or not specified. ^bThe total sum exceeds 188, since some participants worked parttime and studied or were part-time retired. ^cAll participants answered demographics about asthma, but 2 were missing from the Asthma Control Scale. ^dADHD, Autism, OCD, Eating disorder, Personality disorder. ^eUlcer Colitis, Chron’s Disease, Diabetes, Hypothyroid, Celiac Disease, Alopecia Universalis, Psoriasis, Rheumatism, Sjogrens Syndrome. ^fFibromyalgia, Chronic Pain, Irritable Bowel Syndrome.*

Table 4. The validated versions of the Fear of Asthma Symptom scale (FAS) and the Asthma Behavior Checklist (ABC).

FAS	R^2	Item description	Mean	SD
Item 1	0.61	Worry about asthma when leaving home	1.67	1.7
Item 2	0.69	Often worry about asthma	2.34	1.6
Item 3	0.48	Difficult having a good time due to worry about asthma	0.92	1.3
Item 4	0.59	Worry about lung function	2.52	1.8
Item 5	0.61	Sense asthma symptoms, become anxious	2.94	1.7
Item 6	0.54	Constantly aware of breath	2.41	1.6
Item 7	0.54	Often think asthma is a serious disease	2.11	1.7
Item 8	0.55	Anxiety for asthma during the day when waking up	0.90	1.4
Item 9	0.62	When in stress, anxious about asthma	2.06	1.8
Item 10	0.57	Constantly aware of breath changes	1.71	1.6
Item 11	0.52	Asthma symptoms cause fear	2.61	1.7
ABC-8	R^2	Item description	Mean	SD
Item 1	0.48	Prefer not taking the stairs	3.0	1.9
Item 2	0.46	Avoid hurrying	3.3	1.8
Item 3	0.56	Avoid exercise	3.1	1.9
Item 4	0.71	Avoid becoming short of breath	3.5	2.1
Item 5	0.76	Try to do things as calmly as I can	3.2	2.0
Item 6	0.59	Plan my route to avoid walking	2.3	1.8
Item 7	0.58	Rest before activities	3.1	2.1
Item 8	0.75	Hold back not to exert myself	3.2	1.9

Note. FAS: Response range 0–4 (“Do not agree at all” – “Very much agree”).

ABC: Response range 1–7 (“Never” – “Always”).

R² = squared standardized loading on the latent variable.

Table 5. Convergent validity analyzed with average variance extracted (AVE).

Measure	AVE
FAS	.57
ABC-8	.61
CAS	.51
ACT	.39
ASI	.41

Note. AVE > 0.50 is required for convergent validity.

FAS = Fear of Asthma Symptoms Scale. ABC-8 = Asthma.

Behavior Checklist. CAS = Catastrophizing about Asthma Scale.

ACT = Asthma Control Test. ASI = Anxiety Sensitivity Index.

Table 6. Correlations between scales versus the squareroot of AVE.

	FAS	ABC-8	√AVE
FAS		.65	.76
ABC-8	.65		.78
CAS	.87	.60	.71
ACT	-.71	-.61	.63
ASI	.61	.58	.64

Note. AVE = average variance extracted. FAS = Fear of asthma symptoms scale.

ABC-8 = Asthma behavior checklist. CAS = Catastrophizing about asthma scale.

ACT = Asthma control test. ASI = Anxiety sensitivity index.

Table 7. Bivariate correlations.

	ABC -8 (N = 188)	FAS (N = 185)	ACT (N = 185)	ASI (N = 185)	CAS (N = 184)	ABC-8 t2 (N = 177)	FAS t2 (N = 173)
ABC −8		.61	-.42	.54	.56	.88	0.58
FAS	.61		-.55	.57	.83	.61	.85
ACT *	-.42	-.55		-.24	-.55	-.43	-.52
ASI	.54	.57	-.24		.61	.57	.59
CAS	.56	.83	-.55	.61		.59	.77

Note. FAS = Fear of Asthma Symptoms Scale. ABC-8 = Asthma Behavior Checklist. CAS = Catastrophizing About Asthma Scale. ACT = Asthma Control Test. ASI = Anxiety Sensitivity Index.

Bold figures show strong correlations (r= 0.60–0.79), bold and underlined figures very strong correlations (r= 0.80–1.0). * Higher rating on ACT means improved asthma control, while higher rating on all other scales signifies increased problem burden. The ACT is therefore expected to correlate negatively with all other scales. T2 = Repeated assessments after 1 week only on the FAS and the ABC for test-retest analyses.