TABLE 2.

Association of vitamin D concentrations with the risk of asthma.

Vitamin D concentration, nmol/L	Total (N = 435,040)			Female (N = 233,393)			Male (N = 201,647)
	Asthma N (%)	OR (95%CI)	P	Asthma N (%)	OR (95%CI)	P	Asthma N (%)	OR (95%CI)	P
Per SD in concentration	58,635 (13.5)	0.960 (0.951–0.970)	<0.001	33,371 (14.3)	0.970 (0.957–0.983)	<0.001	25,264 (12.5)	0.949 (0.935–0.963)	<0.001
Quartiles
12.8–32.6	15,966 (14.7)	Ref		9,125 (15.7)	Ref		6,841 (13.5)	Ref
32.7–46.8	14,993 (13.7)	0.958 (0.935–0.981)	<0.001	8,515 (14.5)	0.964 (0.933–0.996)	0.027	6,478 (12.8)	0.953 (0.919–0.989)	0.011
46.9–62.0	14,279 (13.1)	0.939 (0.916–0.962)	<0.001	8,103 (13.9)	0.956 (0.925–0.988)	0.008	6,176 (12.2)	0.921 (0.887–0.956)	<0.001
62.1–104.0	13,397 (12.4)	0.909 (0.887–0.933)	<0.001	7,628 (13.0)	0.931 (0.900–0.963)	<0.001	5,769 (11.6)	0.887 (0.853–0.921)	<0.001
		Ptrend<0.001			Ptrend = 0.001			Ptrend < 0.001
Category
Deficient (< 25)	8,378 (15.1)	Ref		4,802 (16.3)	Ref		3,576 (13.8)	Ref
Insufficient (25–50)	25,697 (13.8)	0.936 (0.911–0.962)	<0.001	14,607 (14.7)	0.944 (0.911–0.979)	0.002	11,090 (12.8)	0.931 (0.894–0.970)	0.001
Optimal (> 50)	24,560 (12.7)	0.902 (0.877–0.927)	<0.001	13,962 (13.4)	0.922 (0.889–0.957)	<0.001	10,598 (11.9)	0.881 (0.845–0.919)	<0.001
		Ptrend<0.001			Ptrend < 0.001			Ptrend < 0.001

All models were adjusted for age, sex, BMI, ethnicity, income, education, smoking status, and vitamin D supplements.