Table 2.

Selected baseline characteristics [medians (interquartile range) or number (%)] by season-specific quintile of serum 25(OH)D, ATBC Study

Season-specific quintile of serum 25(OH)D
CharacteristicQ1 (n = 166)Q2 (n = 203)Q3 (n = 206)Q4 (n = 187)Q5 (n = 237)P
Age at blood collection (years)58 (54–62)57 (53–61)56 (53–62)57 (53–61)59 (55–63)0.02
Age at diagnosis (years)69 (66–73)69 (65–73)69 (66–73)69 (65–73)70 (67–74)0.02
Height (cm)173 (169–177)173 (170–178)174 (170–179)174 (170–178)174 (171–178)0.61
Weight (kg)75.6 (69.0–84.3)77.2 (71.0–88.0)77.7 (70.5–86.7)80.0 (71.4–87.8)78.5 (72.1–86.2)0.23
BMI (kg/m2)25.8 (23.6–28.2)26.1 (23.6–28.8)26.0 (23.9–28.3)26.1 (24.5–28.3)25.7 (24.2–28.4)0.50
Cigarettes per day20 (13–30)20 (15–25)20 (15–25)20 (15–25)20 (14–25)0.44
Physically active18 (10.8)42 (20.7)40 (19.4)42 (22.5)53 (22.4)0.06
History of diabetes7 (4.2)5 (2.5)3 (1.5)2 (1.1)5 (2.1)0.35
Family history of prostate cancer11 (6.6)6 (3.0)3 (1.5)15 (8.0)17 (7.2)0.005
Energy intake (kcal/day)2,600 (2,104–3,261)2,643 (2,150–3,197)2,614 (2,206–3,124)2,613 (2,125–3,130)2,582 (2,201–3,160)0.99
Dietary vitamin D (IU/day)3.5 (2.4–4.9)4.1 (2.9–6.2)4.9 (3.3–6.5)4.9 (3.6–6.7)5.9 (4.2–8.4)<0.0001
Dietary calcium (mg/day)1,326 (974–1,825)1,329 (966–1,725)1,306 (1,006–1,708)1,377 (1,044–1,703)1,351 (1,003–1,710)0.85
Ethanol intake (g/day)9.3 (1.6–22.9)9.7 (1.9–24.5)12.1 (2.3–27.1)10.6 (3.4–24)11.8 (3.3–22.9)0.66
Supplemental vitamin D use1 (0.6)9 (4.4)18 (8.7)18 (9.6)32 (13.5)0.0005
Supplemental calcium use15 (9.0)17 (8.4)24 (11.7)21 (11.2)39 (16.5)0.11
Serum cholesterol (mmol/L)6.2 (5.4–6.8)6.2 (5.4–6.9)6.2 (5.4–6.8)6.3 (5.5–7.1)6.1 (5.4–6.8)0.71
Serum α-tocopherol (mg/L)10.6 (8.6–12.9)11.1 (9.8–13.3)11.3 (9.8–13.3)11.8 (10.2–13.9)11.8 (10.3–13.4)<0.0001
Serum β-carotene (µg/L)147 (89–241)169 (116–249)186 (120–259)196 (130–279)213 (139–311)<0.0001
Serum retinol (µg/L)575 (497–634)578 (506–666)588 (512–682)603 (515–684)595 (531–686)0.21
Serum 25(OH)D (nmol/L)14.2 (10.5–18.4)22.7 (20.0–29.9)30.8 (27.3–39.8)41.3 (37.4–50.3)64.1 (53.9–74.3)
Time from baseline to diagnosis (years)11.5 (8.1–14.5)12.7 (8.0–15.1)12.7 (9.0–15.8)12.8 (8.2–15.0)12.8 (9.4–15.7)0.19
Time from diagnosis to death or end of follow-up (years)3.9 (1.8–8.2)4.7 (2.2–9.5)6.6 (2.8–10.2)6.6 (2.6–10.6)6.3 (2.4–10.8)0.0003