Table 3

Interaction between sex and smoking among participants of the Health Survey for England 1995, 1996 and 2001, by alternative definitions of chronic obstructive pulmonary disease

		p Value	Interaction, male × pack years	p Value
	Adjusted OR^* (95% CI)	p Value	Adjusted OR^* (95% CI)	p Value
LLN criteria^†
Sex (male)	1.03 (0.83 to 1.26)	0.814
Pack years: never smoker	1.0
Ever smoker: <1	1.13 (0.65 to 1.96)	0.677	0.50 (0.16 to 1.59)	0.242
1–19	1.70 (1.40 to 2.06)	<0.001	0.87 (0.65 to 1.17)	0.360
20–49	2.99 (2.49 to 3.60)	<0.001	0.97 (0.74 to 1.27)	0.815
50+	4.27 (3.09 to 5.88)	<0.001	0.92 (0.62 to 1.37)	0.681
GOLD criteria^†
Sex (male)	1.77 (1.53 to 2.06)	<0.001
Pack years: never smoker	1.0
Ever smoker: <1	1.05 (0.67 to 1.66)	0.832	0.61 (0.28 to 1.31)	0.204
1–19	1.70 (1.45 to 2.00)	<0.001	0.75 (0.60 to 0.94)	0.012
20–49	2.90 (2.48 to 3.38)	<0.001	0.74 (0.60 to 0.91)	0.004
50+	3.79 (2.85 to 5.04)	<0.001	0.81 (0.58 to 1.13)	0.229
NICE criteria^†
Sex (male)	1.81 (1.37 to 2.39)	<0.001
Pack years: never smoker	1.0
Ever smoker: <1	0.97 (0.39 to 2.42)	0.955	0.21 (0.02 to 1.85)	0.160
1–19	2.70 (2.06 to 3.53)	<0.05	0.66 (0.45 to 0.96)	0.028
20–49	5.58 (4.36 to 7.15)	<0.001	0.64 (0.46 to 0.90)	0.011
50+	8.63 (6.00 to 12.41)	<0.001	0.74 (0.48 to 1.16)	0.187

Numbers in bold refer to values with a significance of p<0.05.
↵* Adjusted for age, sex, pack years of smoking, socioeconomic status and sex × pack years.
↵† Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria18: FEV₁/FVC ratio <0.7; National Institute for Health and Clinical Excellence (NICE) criteria: FEV₁/FVC <0.7 and FEV₁ <80% predicted (equivalent to GOLD stage II)19; lower limit of normal (LLN) criteria20 21: participants with FEV₁/FVC values >1.645 SD below the mean reference value.
FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity.