Table 3 Results of univariate logistic regression analysis of risk factors between birth and 30 months corrected age for wheeze, nocturnal cough, wheeze on exercise (all in the past year) and peak expiratory flow for 219 extremely preterm children at 6 years

	Miss-ing data†	Any wheeze (n = 219)		Night cough (n = 219)		Exercise induced wheeze (n = 218)		Peak expiratory flow (n = 200)
	Miss-ing data†	OR (95% CI)	p Value	OR (95% CI)	p Value	OR (95% CI)	p Value	Coeff, l/min(95% CI)	p Value
Gestational age (per week)	0	0.54 (0.36 to 0.81)	0.003*	0.89 (0.60 to 1.31)	0.55	0.68 (0.45 to 1.05)	0.083	1 (−6 to 9)	0.77
Birthweight SD score	0	1.24 (0.92 to 1.68)	0.15	1.13 (0.84 to 1.51)	0.42	1.27 (0.91 to 1.77)	0.15	1 (−5 to 7)	0.74
Black ethnic group	0	0.81 (0.32 to 2.04)	0.65	1.09 (0.46 to 2.60)	0.84	1.32 (0.52 to 3.36)	0.56	−4 (−20 to 12)	0.63
Singleton	0	2.23 (1.09 to 4.54)	0.027*	1.13 (0.60 to 2.14)	0.7	1.47 (0.70 to 3.09)	0.32	5 (−7 to 18)	0.41
Male sex	0	0.93 (0.53 to 1.64)	0.81	1.15 (0.66 to 2.00)	0.63	1.08 (0.58 to 2.02)	0.81	7 (−4 to 18)	0.20
Clinical chorioamnionitis	2	1.66 (0.85 to 3.24)	0.14	1.29 (0.66 to 2.52)	0.46	2.67 (1.32 to 5.39)	0.006*	3 (−11 to 17)	0.67
Antenatal steroids	1	0.56 (0.28 to 1.12)	0.099	1.06 (0.52 to 2.16)	0.87	0.95 (0.43 to 2.10)	0.9	−13 (−27 to 2)	0.081
Surfactant treatment	0	1.04 (0.46 to 2.33)	0.93	0.85 (0.39 to 1.84)	0.68	0.90 (0.38 to 2.15)	0.82	6 (−10 to 21)	0.49
Postnatal steroids prior to discharge	1	1.07 (0.56 to 2.04)	0.84	1.11 (0.58 to 2.09)	0.76	0.95 (0.47 to 1.92)	0.89	−3 (−10 to 14)	0.69
Postnatal steroids per week of use	1	1.01 (0.91 to 1.11)	0.88	1.01 (0.92 to 1.11)	0.76	1.01 (0.91 to 1.21)	0.81	−1.1 (−3.1 to 0.8)	0.26
BPD (oxygen at 36 weeks PMA)	0	2.32 (1.12 to 4.83)	0.024*	1.59 (0.81 to 3.12)	0.18	1.83 (0.83 to 4.05)	0.14	−18 (−31 to −6)	0.004*
Oxygen at 40 weeks	0	2.02 (1.13 to 3.61)	0.018*	1.59 (0.90 to 2.79)	0.11	1.88 (0.99 to 3.57)	0.055	−17 (−28 to −6)	0.002*
Home oxygen	0	1.79 (0.99 to 3.23)	0.053	1.39 (0.77 to 2.49)	0.27	1.92 (1.01 to 3.66)	0.047*	−17 (−29 to −5)	0.007*
Maternal smoking in pregnancy	3	2.13 (1.17 to 3.88)	0.014*	1.74 (0.97 to 3.15)	0.065	2.35 (1.23 to 4.49)	0.01*	−4 (−16 to 8)	0.46
Mother smoking since discharge home to 30 months	1	2.08 (1.16 to 3.70)	0.014*	1.72 (0.97 to 3.03)	0.062	2.04 (1.08 to 3.85)	0.028*	1 (−10 to 13)	0.81
Mother currently smoking at 30 months	0	2.00 (1.11 to 3.58)	0.02*	1.82 (1.03 to 3.24)	0.04*	2.01 (1.06 to 3.81)	0.032*	3 (−9 to 15)	0.60
Any smoking at home at 30 months	15	2.17 (1.21 to 3.86)	0.009*	1.73 (0.99 to 3.04)	0.056	2.05 (1.08 to 3.88)	0.028*	10 (−1 to 21)	0.08
Damp in house at 30 months	0	2.22 (0.62 to 7.92)	0.22	1.99 (0.56 to 7.09)	0.29	2.28 (0.62 to 8.43)	0.22	−12 (−37 to 13)	0.34
Mould in house at 30 months	2	2.99 (0.65 to 13.8)	0.16	5.14 (0.97 to 27.2)	0.054	4.75 (1.03 to 22.0)	0.046*	13 (−17 to 44)	0.40
Family history of atopy at 30 months	2	1.72 (0.92 to 3.24)	0.091	1.15 (0.64 to 2.09)	0.64	1.30 (0.66 to 2.57)	0.45	2 (−10 to 14)	0.76

*Significant p value; †number where the question was not answered by the parents.
BPD, bronchopulmonary dysplasia; Coeff, coefficient; OR, odds ratio; PMA, postmenstrual age.