Table 3

Mean lung function and prevalence of chronic obstructive pulmonary disease by fifths of total vitamin D intake and serum 25(OH)D concentrations

	Range of vitamin D (μg)	FEV₁ (l)			FVC (l)			FEV₁/FVC ratio			COPD
	Range of vitamin D (μg)	N	Mean	SD	N	Mean	SD	N	Mean	SD	Total N	N	%
Fifths of total vitamin D intake:
1 (lowest)	0.54–2.59	589	2.35	0.69	588	3.33	0.93	588	0.706	0.09	588	133	22.6
2	2.59–3.42	588	2.42	0.67	586	3.40	0.93	586	0.713	0.09	586	104	17.7
3	3.42–5.21	589	2.47	0.68	589	3.46	0.93	589	0.715	0.08	589	113	19.2
4	5.22–7.63	588	2.44	0.67	586	3.41	0.92	586	0.719	0.09	586	98	16.7
5 (highest)	7.64–59.5	588	2.50	0.65	587	3.45	0.90	587	0.728	0.07	587	73	12.4

	Range of vitamin D (nmol/l)	FEV₁ (l)			FVC (l)			FEV₁/FVC ratio			COPD
	Range of vitamin D (nmol/l)	N	Mean	SD	N	Mean	SD	N	Mean	SD	Total N	N	%
Fifths of serum 25(OH)D concentration:
1 (lowest)	11.4–27.4	241	2.27	0.62	240	3.13	0.83	240	0.726	0.09	240	41	17.1
2	27.5–38.2	239	2.36	0.65	239	3.26	0.87	239	0.728	0.08	239	37	15.5
3	38.3–48.0	244	2.38	0.67	244	3.31	0.90	244	0.721	0.09	244	41	16.8
4	48.1–62.8	234	2.46	0.71	233	3.43	0.96	233	0.717	0.08	233	50	21.5
5 (highest)	62.9–336.5	239	2.50	0.69	239	3.52	0.92	239	0.712	0.09	239	49	20.5

FEV₁, forced expiratory volume in 1 s; FVC, forced vital capacity; 25(OH)D, 25 hydroxy vitamin D.