Table 2.

Mean total 25(OH)D levels (ng/mL) by age group, season of blood draw and study centre location in cases and controls

	All Prostate Cancer Cases (n=1447)			All Controls (n=1449)			p for differencea
	Mean 25(OH)D (ng/mL)	SD	p-valueb	Mean 25(OH)D (ng/mL)	SD	p-valueb
All	23.0	8.7		22.9	8.4		0.72
Age group
50-54*	22.9	8.8		20.9	7.9		0.05
55-59	22.3	8.4	0.53	22.7	8.8	0.04	0.63
60-64	22.8	8.8	0.96	23.0	8.2	0.01	0.70
>=65	23.7	8.8	0.31	23.5	8.3	≤0.001	0.71
p for linear trendc			0.06			≤0.001
Centre Location
North*	23.5	9.1		23.7	8.4		0.62
South	22.6	8.3	0.06d	22.2	8.3	0.005d	0.31
Season of blood draw
Winter*	18.9	7.4		19.3	8.0		0.50
Spring	22.4	8.4	<0.001	22.4	7.6	<0.001	0.94
Summer	27.0	8.8	<0.001	26.9	7.9	<0.001	0.76
Autumn	23.1	8.1	<0.001	22.8	8.1	<0.001	0.61

^*Reference category

^aCalculated using a t-test

^bp-value calculated from regression models, containing total 25(OH)D level and the variable of interest.

^cp-value for linear trend calculated by treating categorical variable as continuous in regression model.

^dRegression model additionally adjusted for season of blood draw

SD=standard deviation