Table 4.

Hazard ratios for overall mortality, colorectal cancer-specific mortality, and 5-year overall mortality among colorectal cancer patients by quartile of plasma total 25-hydroxyvitamin D, bioavailable 25-hydroxyvitamin D, and free 25-hydroxyvitamin D

	Hazard ratio (95% confidence interval)				Ptrend
	Quartile 1	Quartile 2	Quartile 3	Quartile 4
Total 25-hydroxyvitamin D
Mean (SD), ng/mL	15.6 (4.3)	23.7 (3.7)	29.4 (3.8)	40.5 (9.0)
No. of patients	155	158	158	156
Overall mortality
No. of events	74	88	89	77
Base modela	Referent	1.19 (0.87–1.63)	1.22 (0.89–1.67)	0.93 (0.67–1.30)	0.70
Multivariable modelb	Referent	1.18 (0.84–1.65)	1.13 (0.80–1.59)	0.72 (0.49–1.05)	0.09
Model further adjusted for VDBPc	Referent	1.18 (0.84–1.65)	1.14 (0.81–1.61)	0.73 (0.50–1.07)	0.11
Colorectal cancer-specific mortality
No. of events	38	51	57	41
Base modela	Referent	1.29 (0.85–1.98)	1.47 (0.97–2.23)	0.97 (0.61–1.53)	0.97
Multivariable modelb	Referent	1.22 (0.77–1.93)	1.45 (0.92–2.30)	0.57 (0.34–0.97)	0.08
Model further adjusted for VDBPc	Referent	1.23 (0.78–1.96)	1.51 (0.95–2.40)	0.60 (0.35–1.01)	0.12
5-year overall mortality
No. of events	49	53	58	43
Base modela	Referent	1.00 (0.68–1.48)	1.12 (0.76–1.65)	0.74 (0.48–1.12)	0.25
Multivariable modelb	Referent	0.92 (0.60–1.40)	1.05 (0.69–1.59)	0.48 (0.30–0.78)	0.01
Model further adjusted for VDBPc	Referent	0.92 (0.60–1.41)	1.08 (0.71–1.65)	0.50 (0.31–0.81)	0.02
Bioavailable 25-hydroxyvitamin Dd
Mean (SD), ng/mL	1.8 (0.7)	2.9 (0.7)	3.9 (0.8)	6.5 (2.3)
No. of patients	146	154	151	152
Overall mortality
No. of events	65	85	84	77
Base modela	Referent	1.22 (0.88–1.69)	1.25 (0.90–1.74)	1.16 (0.83–1.63)	0.41
Multivariable modelb	Referent	1.11 (0.78–1.59)	1.12 (0.78–1.61)	1.19 (0.82–1.73)	0.39
Colorectal cancer-specific mortality
No. of events	38	50	47	47
Base modela	Referent	1.21 (0.79–1.85)	1.14 (0.74–1.76)	1.17 (0.76–1.81)	0.59
Multivariable modelb	Referent	1.07 (0.66–1.71)	1.01 (0.61–1.65)	1.26 (0.77–2.06)	0.43
5-year overall mortality
No. of events	41	54	53	49
Base modela	Referent	1.19 (0.79–1.79)	1.16 (0.77–1.76)	1.10 (0.72–1.69)	0.72
Multivariable modelb	Referent	1.07 (0.68–1.69)	1.03 (0.65–1.63)	1.14 (0.71–1.82)	0.66
Free 25-hydroxyvitamin Dd
Mean (SD), pg/mL	4.5 (1.6)	7.0 (1.6)	9.4 (1.7)	15.8 (5.5)
No. of patients	147	151	153	152
Overall mortality
No. of events	66	81	79	85
Base modela	Referent	1.18 (0.85–1.63)	1.14 (0.82–1.58)	1.33 (0.96–1.85)	0.12
Multivariable modelb	Referent	1.18 (0.82–1.69)	1.11 (0.77–1.59)	1.36 (0.94–1.95)	0.15
Colorectal cancer-specific mortality
No. of events	38	49	44	51
Base modela	Referent	1.21 (0.79–1.86)	1.04 (0.67–1.62)	1.31 (0.85–2.01)	0.35
Multivariable modelb	Referent	1.18 (0.73–1.90)	1.05 (0.64–1.70)	1.35 (0.83–2.18)	0.32
5-year overall mortality
No. of events	42	50	48	57
Base modela	Referent	1.09 (0.72–1.65)	1.01 (0.67–1.54)	1.28 (0.85–1.92)	0.29
Multivariable modelb	Referent	1.03 (0.65–1.64)	0.97 (0.61–1.53)	1.29 (0.82–2.02)	0.31

Abbreviations: SD, standard deviation; VDBP, vitamin D binding protein.

^aAdjusted for age at diagnosis (continuous) and season of blood collection (summer, fall, winter, spring).

^bAddtionally adjusted for sex, body mass index (continuous), physical activity (continuous), cancer stage (I to IV or unknown), grade of tumor differentiation (well differentiated, moderately differentiated, poorly differentiated, unknown), location of primary tumor (proximal colon, distal colon, rectum, unknown), and year of diagnosis (continuous).

^cAdditionally adjusted for vitamin D binding protein levels (quartiles or missing).

^dCalculated by total 25-hydroxyvitamin D, vitamin D binding protein, and albumin levels and the constant affinity of vitamin D binding protein and albumin for 25-hydroxyvitamin D (6×10⁵ and 7×10⁸, respectively).