TABLE 3.

MULTIVARIABLE ANALYSIS OF THE RAW VARIABLE SET IN RELATION TO ASTHMA SEVERITY (MILD VS. MODERATE–SEVERE)

Variable	Full Covariate Set Models
	Model 1 (AIC = 383)			Model 2 (AIC = 300)
	OR	95% CI	P Value	OR	95% CI	P Value
Age, yr	1.09	0.97–1.23	0.1336	1.01	0.86–1.19	0.8864
Sex, female vs. male	1.17	0.64–2.16	0.6085	1.15	0.52–2.52	0.7358
Age of asthma onset, yr	0.86	0.78–0.95	0.0031	0.9	0.79–1.03	0.1293
BMI, obese vs. normal	2.11	0.66–6.78	0.2101	1.55	0.38–6.28	0.5389
BMI, overweight vs. normal	0.35	0.14–0.85	0.0208	0.25	0.08–0.8	0.0192
Allergic rhinitis	1	0.5–2	0.9987	0.75	0.3–1.85	0.5273
Allergic conjunctivitis	0.59	0.08–4.32	0.6052	0.5	0.05–4.97	0.5557
Eczema	1.63	0.36–7.43	0.5297	2.44	0.39–15.19	0.3405
Maternal allergic rhinitis	0.72	0.23–2.29	0.5838	1	0.26–3.88	0.9964
Maternal eczema	0.93	0.12–7.03	0.9456	1.3	0.11–15.66	0.8378
Paternal allergic rhinitis	0.48	0.11–2.17	0.3403	0.81	0.11–5.78	0.833
Paternal eczema	3.58	0.43–29.76	0.2375	1.65	0.05–52.19	0.7753
Maternal asthma	0.69	0.17–2.74	0.5982	1.12	0.16–7.73	0.9077
Paternal asthma	3.51	1.16–10.64	0.0264	2.92	0.69–12.39	0.147
Exposure to tobacco smoke	1.34	0.72–2.5	0.355	1.09	0.49–2.39	0.8383
Presence of animals or pets in the home	0.79	0.24–2.59	0.7026	0.8	0.17–3.64	0.769
IgE, per log higher	0.84	0.64–1.09	0.191	0.77	0.55–1.09	0.1387
Eosinophil, %	1.02	0.93–1.12	0.7172	1.03	0.91–1.16	0.6615
Atopy	1.44	0.69–3.03	0.3349	1.19	0.46–3.07	0.7165
FEV1, % predicted				0.94	0.9–0.98	0.0035
FVC, % predicted	0.93	0.9–0.96	<0.0001	0.95	0.92–0.98	0.0021
FEV1/FVC ratio	0.9	0.84–0.96	0.0022	0.92	0.85–1	0.0374
FEF25-75, % predicted	0.99	0.97–1.01	0.2101	0.98	0.96–1.01	0.1558
% Fall in FEV1 after exercise (Q1 vs. Q4)	0.42	0.03–6.27	0.5324	0.09	0–5.52	0.2554
% Fall in FEV1 after exercise (Q2 vs. Q4)	0.35	0.06–2.21	0.2644	0.53	0.05–5.73	0.6037
% Fall in FEV1 after exercise (Q3 vs. Q4)	0.51	0.13–2.04	0.3421	0.57	0.09–3.56	0.5515
Bronchodilator reversibility (Q1 vs. Q4)	1.65	0.43–6.4	0.467	3.36	0.58–19.26	0.1745
Bronchodilator reversibility (Q2 vs. Q4)	2.12	0.91–4.97	0.0831	2.18	0.69–6.88	0.1852
Bronchodilator reversibility (Q3 vs. Q4)	0.68	0.3–1.54	0.3529	0.99	0.36–2.71	0.9829
PC20 methacholine (Q1 vs. Q4)	2.52	0.19–32.96	0.4803	0.4	0.01–11.9	0.599
PC20 methacholine (Q2 vs. Q4)	1.45	0.05–39.25	0.8264	0.08	0–1428.31	0.6191
PC20 methacholine (Q3 vs. Q4)	1.49	0.11–19.81	0.7638	1.49	0.07–29.86	0.7961
Asthma symptoms within the last 4 wk				2.52	0.94–6.74	0.0655
No. of exacerbations within the last year	1.05	0.95–1.16	0.3488	1	0.87–1.15	0.9753
No. of hospitalizations	0.94	0.46–1.93	0.868	0.95	0.42–2.16	0.9025
ICS > 300 μg* vs. none				3.58	1.37–9.36	0.0093
ICS ≤ 300 μg* vs. none				0.98	0.38–2.58	0.9743
LABA				56.33	11.38–278.94	<0.0001
Montelukast				7.08	1.59–31.44	0.0101
Stepwise-selected Variable	Stepwise Models
	Model 3 (AIC = 357)			Model 4 (AIC = 260)
	OR	95% CI	P Value	OR	95% CI	P Value
Age of asthma onset, yr	0.89	0.81–0.97	0.0057
FEV1, % predicted				0.95	0.92–0.97	0.0003
FVC, % predicted	0.93	0.91–0.95	<0.0001	0.96	0.94–0.99	0.0018
FEV1/FVC ratio	0.88	0.85–0.91	<0.0001
FEF25-75, % predicted				0.97	0.95–0.98	<0.0001
Asthma symptoms within the last 4 wk				3.01	1.35–6.72	0.0071
ICS >300 μg* vs. none				4.26	1.91–9.5	0.0004
ICS ≤300 μg* vs. none				1.35	0.6–3.05	0.4694
LABA				34.02	9.51–121.7	<0.0001
Montelukast				6.6	1.69–25.84	0.0067

Definition of abbreviations: AIC = Akaike Information Criterion; BMI = body mass index; CI = confidence interval; FEF = forced expiratory flow; ICS = inhaled corticosteroids; LABA = long-acting β₂-agonists; OR = odds ratio; Q1 = 1st quartile; Q2 = 2nd quartile; Q3 = 3rd quartile; Q4 = 4th quartile; SABA = short-acting β₂-agonists.

Logistic regression models: Model 1 excluded FEV₁, symptoms within the last 4 weeks, and medication step as they were used to define severity; Model 2 included all variables; Model 3 and 4 were stepwise of 1 and 2.

^*Betamethasone-equivalent dosage.