Table 4– Crude associations between potential determinants and the bronchodilator-induced change in lung function

	ΔR_rs₆ % baseline			log₁₀(−ΔR_rs₆(z-score)+2)			√(ΔAX+100) % baseline
Continuous variables	B	se	p-value	B	se	p-value	B	se	p-value
Current height cm	0.014	0.137	0.920	−0.002	0.001	0.240	−0.043	0.018	0.018
Current weight kg	−0.155	0.260	0.552	0.001	0.002	0.872	−0.093	0.034	0.007
Gestational age weeks	0.793	0.364	0.030	−0.008	0.003	0.024	0.084	0.048	0.083
Birth weight kg	2.853	1.134	0.012	−0.028	0.011	0.008	0.225	0.151	0.137
Categorical variables	Mean	se	p-value^#	Mean	se	p-value^#	Mean	se	p-value^#
Postnatal ETS
Never	−22.3	0.7	Ref.	0.505	0.007	Ref.	6.94	0.09	Ref.
First in first year	−26.4	2.4	0.056	0.544	0.023	0.054	6.61	0.33	0.240
First after first year	−23.6	2.2	0.596	0.500	0.020	0.825	6.74	0.25	0.514
LRTI
Never	−20.8	1.1	Ref.	0.487	0.095	Ref.	7.26	0.14	Ref.
First in first year	−21.8	3.5	0.814	0.494	0.031	0.863	6.61	0.38	0.201
First after first year	−24.2	1.1	0.025	0.525	0.010	0.008	6.69	0.13	0.003
Number of LRTIs
0	−20.8	1.1	Ref.	0.478	0.095	Ref.	7.26	0.14	Ref.
1	−24.1	1.7	0.101	0.521	0.016	0.074	6.47	0.20	0.002
>1	−24.9	1.8	0.047	0.535	0.019	0.014	6.73	0.23	0.045
Timing of wheeze
Never	−20.9	1.1	Ref.	0.487	0.097	Ref.	7.22	0.14	Ref.
Early/transient	−23.0	1.2	0.207	0.512	0.011	0.113	6.79	0.15	0.047
Late onset	−26.6	6.1	0.267	0.589	0.0.73	0.034	5.74	0.63	0.027
Persistent	−25.4	2.0	0.038	0.543	0.0.20	0.006	6.49	0.27	0.009
Number of wheeze episodes
0	−20.9	1.1	Ref.	0.487	0.097	Ref.	7.22	0.14	Ref.
1	−23.0	1.7	0.335	0.512	0.017	0.218	6.92	0.22	0.279
>1	−25.1	1.3	0.015	0.539	0.013	0.001	6.45	0.18	0.001
Inhalant atopy
Never	−21.9	0.7	Ref.	0.502	0.007	Ref.	7.00	0.10	Ref.
First at 1 year	−30.1	3.4	0.005	0.593	0.032	0.001	5.82	0.50	0.003
First at 4 years	−23.4	1.2	0.373	0.506	0.012	0.776	7.02	0.19	0.925
Number of inhalant allergens
0	−21.9	0.7	Ref.	0.502	0.007	Ref.	7.00	0.10	Ref.
1	−25.3	1.2	0.075	0.523	0.012	0.233	6.85	0.21	0.564
>1	−24.4	2.7	0.268	0.532	0.025	0.168	6.57	0.37	0.175
Food atopy
Never	−21.9	0.7	Ref.	0.501	0.006	Ref.	6.99	0.09	Ref.
First at 1 year	−24.2	1.8	0.203	0.521	0.018	0.245	7.05	0.27	0.799
First at 4 years	−26.0	2.8	0.117	0.542	0.027	0.097	6.53	0.38	0.214
Number of food allergens
0	−21.9	0.7	Ref.	0.501	0.006	Ref.	6.99	0.09	Ref.
1	−22.3	1.8	0.825	0.502	0.016	0.926	6.95	0.20	0.891
>1	−30.3	2.4	0.002	0.571	0.022	0.005	6.84	0.55	0.686

Numbers in bold indicate p<0.05. Δ: change (expressed as relative change compared to baseline and as z-score); R_rs₆: respiratory resistance at 6 Hz; AX: area under the reactance curve; B: unstandardised regression coefficient; ETS: environmental tobacco smoke; LRTI: lower respiratory tract infection.^#: least-significant difference post hoc test.