Smoking, Urban Housing and Work-Aggravated Asthma are Associated with Asthma Severity in a Cross-Sectional Observational Study

Figures & data

Table 1 Patient Characteristics

Variables	Data Available n=	Number (%)	Mean ± SD
Age at asthma onset (years)	948		27 ± 21
Age at inclusion (years)	948		54 ± 16
Sex: Female	948	592 (62.5%)
Body Mass Index (kg/m^2)	948		28 ± 6
Education: secondary or lower	726	476 (65.5%)
Work-aggravated asthma	948	120 (12.6%)
Occupational status	919
Active		395 (43.0%)
Retired		328 (35.7%)
Unemployed		196 (21.3%)
Smoking history (pack.years)	948		8 ± 13
Active smoker		104 (10.1%)
Former smoker		291 (30.7%)
Type of housing	948
Urban		465 (49%)
Suburban		245 (25.8%)
Rural		238 (25.2%)
Allergy (any)	948	525 (55.4%)
Food allergy		92 (9.7%)
Atopic dermatitis		137 (14.4%)
Chronic rhinitis		439 (46.3%)
Positive aeroallergen skin prick test (any)	694	491 (51.8%)
House dust mite		385 (40.6%)
Grass pollen		231 (24.4%)
Cat		177 (18.7%)
Serum total IgE (IU/L)	595		530 ± 1046
Blood eosinophil count (/mm3)	716		447 ± 459

Table 2 ASSESS Score Components

Score	Number of Points	Number of Patients
ACT score
23–25	0	139 (14.6%)
20–22	1	159 (16.7%)
17–19	2	152 (16.0%)
14–16	3	171 (18.0%)
11–13	4	130 (13.7%)
8–10	5	118 (12.4%)
5–7	6	79 (8.3%)
Pre-bronchodilator FEV1
FEV > 80% predicted	0	206 (21.7%)
FEV1 70–80% predicted	1	63 (6.6%)
FEV1 60–70% predicted	2	177 (18.6%)
FEV1 < 60% predicted	3	502 (52.9%)
Therapy
No treatment	0	0 (0.0%)
SABA alone	1	0 (0.1%)
Low dose ICS (< 500 µg/d beclometasone)	2	5 (0.5%)
Low dose ICS + LABA	3	41 (4.3%)
Medium/high dose ICS (≥500 µg/d) + LABA	4	534 (56.3%)
High dose ICS (>1000 µg/d) + LABA + LAMA	5	368 (38.8%)
Long-term oral corticosteroids	+1	168 (17.7%)
Biologics	+1	276 (29.1%)
Exacerbations ≥ 1 in the last 6 months
Requiring oral corticosteroids	2	443 (46.7%)
Requiring hospitalization	4	249 (26.2%)

Abbreviations: SABA, Short-acting beta-agonists; LABA, Long-acting beta-agonists; ACT, Asthma Control Test; FEV1, Forced expiratory volume in 1 second; LAMA, Long-acting muscarinic antagonists; ICS, Inhaled corticosteroids.

Table 3 Markers Associated with the ASSESS Score by Bivariate and Multivariate Analysis

Characteristic	N	Bivariate			Multivariate
		Beta	95% CI	p-value	Beta	95% CI	p-value
Female sex (vs male)	948	0.64	0.19, 1.1	0.005	0.86	0.36, 1.4	<0.001
Age	948	0.01	0.00, 0.03	0.047	0.01	−0.01, 0.04	0.256
Smoking (pack.years)	948	0.03	0.02, 0.05	<0.001	0.03	0.01, 0.05	0.008
Education secondary or lower (vs higher)	726	1.1	0.63, 1.6	<0.001	0.85	0.33, 1.4	0.001
Employment status: Inactive (vs active or retired)	919	1.3	0.68, 1.8	<0.001	0.85	0.23, 1.5	0.024
Work-aggravated asthma	948	0.72	0.07, 1.4	0.029	0.82	0.12, 1.5	0.022
Urban habitat (vs rural)	948	0.86	0.43, 1.3	<0.001	1.1	0.67, 1.6	<0.001
Any allergic disease	948	0.03	−0.41, 0.47	0.895
Number of allergic diseases (vs 0)	948			0.762
1		0.13	−0.35, 0.61
2		−0.27	−1.0, 0.47
3		0.15	−1.4, 1.7
Atopy	914	−0.04	−0.51, 0.43	0.861
Number of positive aeroallergen skin prick test (vs 0)	694			0.961
1		−0.03	−0.52, 0.46
2		0.03	−0.60, 0.67
≥ 3		−0.29	−1.4, 0.86
Blood eosinophils (/µL)	716	0.00	0.00, 0.00	0.130
Blood eosinophils >300/µL	716	0.30	−0.21, 0.81	0.244

Notes: N: Number of patients with available data. Beta: Beta-coefficient of the regression line.

Figure 1 Asthma severity in patients with urban housing (A), patients with work-aggravated asthma (B) and ever-smokers (C). Asthma severity was quantitated by the ASSESS score. Violin plots show probability density of the data at different values, medians and quartiles. p-value for urban housing <0.001. p-value for work-aggravated asthma = 0.029. p-value for smoking = 0.025.

Table 4 Variables Associated with the Components of the ASSESS Score in Multivariate Analysis

Components	Variables	β-Coefficient (95% CI)	p
High ACT score	Sex: Female (vs male)	0.47 (0.22–0.72)	<0.001
	Tobacco history (pack.years)	0.01 (0.00–0.02)	0.004
	Occupational status: Unemployed (vs active or retired)	0.44 (0.12–0.75)	0.006
	Work-aggravated asthma	0.53 (0.17–0.88)	0.004
	Urban housing (vs rural)	0.39 (0.16–0.63)	0.001
Low FEV1	Tobacco history (pack.years)	1.01 (1.00–1.02)	0.019
	Education: Secondary or lower (vs higher)	1.93 (1.45–2.57)	<0.001
	Occupational status: Unemployed (vs active or retired)	1.53 (1.08–2.17)	0.017
	Urban housing (vs rural)	1.41 (1.08–1.83)	0.011
Number of exacerbations	Sex: Female (vs male)	0.58 (0.09–1.1)	0.021
	Tobacco history (pack.years)	0.02 (0.00–0.04)	0.016
	Occupational status: Unemployed (vs active or retired)	0.74 (0.12–1.4)	0.020
	Urban housing (vs rural)	0.59 (0.12–1.1)	0.014
High therapeutic load	Education: Secondary or lower (vs higher)	1.47 (1.04–2.09)	0.029