Determinants for a low health-related quality of life in asthmatics

Figures & data

Figure 1. Study population and subgroups 1990–2003.

Table I. The characteristics of the study sample (n (%) and mean ± SD).

	All (n = 616)	16 y (n = 160)	30–39 y (n = 233)	60–69 y (n = 223)	P value
Women	359 (58)	85 (53)	138 (59)	136 (61)	0.29
FEV1 % of predicted	93 ± 15	96 ± 3	94 ± 15	90 ± 17	< 0.05
Skin prick test reactivity
None	293 (48)	53 (33)	72 (31)	168 (75)	< 0.001
1 type of allergen^a	132 (21)	30 (19)	57 (25)	45 (20)
2 types of allergens	124 (20)	46 (29)	72 (31)	6 (3)
3 types of allergens	51 (8)	24 (15)	24 (10)	3 (1)
4 types of allergens	15 (2)	7 (4)	7 (3)	1 (0)
Airway responsiveness to irritants
None	55 (9)	10 (6)	21 (9)	24 (11)	< 0.01
1 irritant	112 (18)	31 (19)	42 (18)	39 (17)
2 irritants	144 (23)	38 (24)	56 (24)	50 (22)
3 irritants	157 (26)	46 (29)	65 (28)	46 (21)
4 irritants	108 (18)	27 (17)	39 (17)	42 (19)
5 irritants	38 (16)	8 (5)	8 (3)	22 (10)
Respiratory symptom severity
None	57 (9)	15 (9)	22 (9)	20 (9)	< 0.01
Wheeze last year	90 (15)	27 (17)	43 (18)	20 (9)
Nocturnal symptoms	402 (65)	108 (68)	148 (64)	146 (65)
Daily symptoms	67 (11)	10 (6)	20 (9)	37 (17)
Allergic rhinitis	231 (43)	75 (50)	107 (53)	49 (27)	< 0.001
Asthma medication
None	324 (54)	65 (42)	119 (52)	140 (65)	< 0.001
Bronchodilators	87 (15)	36 (23)	32 (14)	19 (9)
Inhaled corticosteroids	162 (27)	52 (34)	61 (27)	49 (23)
Oral corticosteroids	24 (4)	2 (1)	15 (7)	7 (3)
Smoking history
Non-smokers	334 (54)	147 (92)	70 (30)	117 (52)	< 0.001
Ex-smokers	135 (22)	5 (3)	71 (31)	59 (26)
Smokers	146 (24)	8 (5)	91 (39)	47 (21)
Oral tobacco use	84 (14)	24 (15)	41 (18)	19 (9)	< 0.05
Emergency visits ever
None	358 (59)	82 (52)	134 (58)	142 (64)	0.16
≥1 emergency department visit	128 (21)	36 (23)	53 (23)	39 (17)
≥hospitalization	125 (20)	40 (25)	43 (19)	42 (19)
Sick-leave during last 12 months
None	526 (85)	118 (74)	197 (85)	211 (95)	< 0.001
1–8 days	37 (6)	20 (13)	16 (7)	1 (0)
8–30 days	44 (7)	20 (13)	16 (7)	8 (4)
30–90 days	5 (1)	1 (1)	3 (1)	1 (0)
>90 days	4 (1)	1 (1)	1 (0)	2 (1)
Living in an apartment	190 (33)	31 (21)	74 (32)	85 (43)	< 0.001
Living in a city	371 (64)	102 (69)	152 (67)	117 (57)	< 0.05
Health-related quality of life
Symptom score	3.7 ± 1.3	4.0 ± 1.1	3.8 ± 1.4	3.7 ± 1.3	0.12
Social well-being	5.4 ± 0.9	5.4 ± 0.9	5.3 ± 0.9	5.5 ± 1.0	< 0.05
Physical well-being	4.2 ± 0.8	4.4 ± 0.8	4.3 ± 0.8	4.1 ± 0.8	< 0.001
Mental well-being	5.1 ± 1.0	5.2 ± 1.0	5.1 ± 1.1	5.1 ± 1.0	0.57

^aPollen, pets, mites, and mould.

Table II. Determinants of asthma subjects. Multivariate linear regression, imputed data (n = 616). A negative value indicates lower quality of life. All coefficients for the score variables are per unit increase in the score unless noted otherwise.

	Symptom score		Social well-being		Physical well-being		Mental well-being		P value
Male sex	0.37	(0.14 to 0.60)	0.07	(–0.12 to 0.26)	–0.02	(–0.16 to 0.12)	0.22	(0.04 to 0.41)	< 0.001
Age group
16 y	–0.05	(–0.34 to 0.24)	0.03	(–0.19 to 0.2)	–0.02	(–0.19 to 0.16)	–0.07	(–0.31 to 0.17)	0.102
30–39 y		0		0		0		0
60–69 y	–0.08	(–0.36 to 0.19)	0.04	(–0.18 to 0.2)	–0.19	(–0.35 to –0.02)	0.01	(–0.21 to 0.23)
Skin prick test reactivity score	0.16	(0.04 to 0.28)	0.03	(–0.06 to 0.13)	0.05	(–0.02 to 0.12)	0.10	(0.01 to 0.19)	0.059
Airway responsiveness to irritants
None	0.47	(0.07 to 0.86)	–0.14	(–0.45 to 0.17)	0.18	(–0.05 to 0.42)	0.04	(–0.28 to 0.36)	< 0.001
1 irritant	0.59	(0.26 to 0.92)	0.35	(0.09 to 0.60)	0.43	(0.24 to 0.62)	0.37	(0.11 to 0.62)
2 irritants	0.14	(–0.17 to 0.45)	0.17	(–0.05 to 0.40)	0.22	(0.05 to 0.40)	0.16	(–0.07 to 0.40)
3 irritants		0		0		0		0
4 irritants	–0.08	(–0.41 to 0.25)	0.11	(–0.14 to 0.36)	0.13	(–0.07 to 0.32)	0.05	(–0.22 to 0.32)
5 irritants	–0.41	(–0.88 to 0.06)	0.24	(–0.14 to 0.62)	0.20	(–0.07 to 0.48)	0.20	(–0.17 to 0.58)
Respiratory symptom severity score
Females	–0.29	(–0.48 to –0.10)	–0.08	(–0.22 to 0.05)	–0.15	(–0.27 to –0.04)	–0.24	(–0.39 to –0.09)	0.187
Males	–0.27	(–0.47 to –0.06)	0.04	(–0.12 to 0.21)	–0.02	(–0.14 to 0.10)	0.00	(–0.16 to 0.17)
Allergic rhinitis	–0.24	(–0.49 to 0.02)	–0.13	(–0.36 to 0.10)	–0.05	(–0.20 to 0.10)	–0.21	(–0.41 to –0.01)	0.169
Asthma medication score	0.10	(0.01 to 0.19)	0.05	(–0.03 to 0.12)	0.06	(0.00 to 0.11)	0.03	(–0.05 to 0.10)	0.154
Smoking habits
Non-smokers		0		0		0		0	0.011
Ex-smokers	–0.11	(–0.39 to 0.17)	–0.14	(–0.35 to 0.07)	–0.28	(–0.45 to –0.11)	–0.25	(–0.49 to –0.02)
Smokers	–0.36	(–0.65 to –0.08)	–0.24	(–0.47 to –0.01)	–0.27	(–0.44 to –0.10)	–0.34	(–0.57 to –0.11)
Oral tobacco use	0.03	(0.32 to 0.38)	0.27	(0.03 to 0.52)	0.15	(–0.05 to 0.34)	0.13	(–0.13 to 0.39)	0.188
Sick-leave during last 12 months
No sick leave		0		0		0		0	0.025
<8 days	–0.23	(–0.65 to 0.20)	–0.06	(–0.38 to 0.27)	–0.01	(–0.26 to 0.25)	–0.14	(–0.49 to 0.21)
8–30 days	–0.81	(–1.21 to –0.41)	–0.24	(–0.53 to 0.06)	–0.24	(–0.47 to 0.00)	–0.44	(–0.76 to –0.11)
30–90 days	–1.13	(–2.20 to –0.07)	–0.28	(–1.14 to 0.59)	0.08	(–0.58 to 0.75)	–0.51	(–1.41 to 0.40)
>90 days	–1.23	(–2.42 to –0.04)	–0.56	(–1.60 to 0.49)	–0.39	(–1.13 to 0.34)	–0.98	(–1.98 to 0.03)

Figure 2. Distribution of the Gothenburg Quality of Life instrument subscales by sex. Solid dots indicate mean values, and solid line segments inside the boxes indicate the 25th, 50th, and 75th percentiles, respectively. Small ticks indicate observations outside the 5th and 95th percentiles. The x-axis represents the score on the seven-step Likert scale ranging from 1 = ‘very bad’, to 7 = ‘excellent/could not be better’.