Table 2

Decline in lung function in participants with more than one spirometric measurement using a non-parametric trend test

Smoking history	Lung function	Seasonally adjusted plasma 25-hydroxyvitamin D quintiles
Smoking history	Lung function	1st (lowest)	2nd	3rd	4th	5th (highest)	P for trend
All participants (N=5819)	Decline in FEV₁ % predicted/year	0.47 (0.38 to 0.56)	0.29 (0.23 to 0.27)	0.18 (0.11 to 0.26)	0.24 (0.19 to 0.33)	0.19 (0.13 to 0.28)	2×10⁻⁵
All participants (N=5819)	Decline in FVC % predicted/year	0.30 (0.18 to 0.38)	0.16 (0.05 to 0.22)	0.06 (0.00 to 0.14)	0.14 (0.08 to 0.20)	0.09 (0.02 to 0.16)	4×10⁻⁴
Continuous smokers (N=2250)	Decline in FEV₁ % predicted/year	0.69 (0.54 to 0.82)	0.61 (0.41 to 0.71)	0.32 (0.18 to 0.45)	0.59 (0.44 to 0.71)	0.43 (0.32 to 0.55)	0.02
Continuous smokers (N=2250)	Decline in FVC % predicted/year	0.46 (0.33 to 0.56)	0.21 (0.12 to 0.31)	0.12 (0.00 to 0.24)	0.24 (0.11 to 0.40)	0.16 (0.02 to 0.24)	0.003
Quitters (N=2295)	Decline in FEV₁ % predicted/year	0.26 (0.09 to 0.40)	0.22 (0.11 to 0.31)	0.14 (0.03 to 0.30)	0.19 (0.09 to 0.28)	0.13 (0.06 to 0.28)	0.4
Quitters (N=2295)	Decline in FVC % predicted/year	0.12 (0.02 to 0.29)	0.13 (−0.01 to 0.24)	0.02 (−0.07 to 0.16)	0.11 (0.02 to 0.21)	0.13 (0.02 to 0.22)	0.7
Never smokers (N=1274)	Decline in FEV₁ % predicted/year	0.14 (−0.44 to 0.18)	0.06 (−0.24 to 0.08)	0.02 (−0.20 to 0.12)	0.06 (−0.18 to 0.12)	0.00 (−0.10 to 0.09)	0.3
Never smokers (N=1274)	Decline in FVC % predicted/year	0.08 (−0.12 to 0.37)	−0.02 (−0.16 to 0.26)	0.06 (−0.05 to 0.15)	0.06 (−0.08 to 0.19)	0.00 (−0.09 to 0.11)	0.2