Table 2.

Serum 25-OH-vitamin D and optical density of immunohistochemically detected 8-OH-dG in colorectal crypts at baseline and 6 months of follow-up

Baseline6 mo follow-upAbsolute treatment effect*Relative effect
nMean (SE)PnMean (SE)PnMean (SE)P
(A) Serum vitamin D measurements
25-OH-vitamin D, ng/mL
    Placebo2320.7 (1.7)2118.2 (1.8)2101.00
    Calcium2325.7 (1.7)0.052123.4 (1.7)0.03210.2 (1.8)0.921.03
    Vitamin D2321.0 (1.7)0.812229.5 (1.7)<0.00012210.9 (1.8)<0.00011.59
    Calcium + vitamin D2320.9 (1.7)0.842128.9 (1.7)<0.00012110.5 (1.8)<0.00011.57
(B) 8-OH-dG§ labeling optical density in colorectal crypts
Entire crypts
    Placebo232,360.8 (193.2)212,509.0 (202.1)2101.00
    Calcium232,349.4 (193.2)0.97211,946.2 (202.1)0.0521−551.5 (374.4)0.140.78
    Vitamin D232,318.4 (193.2)0.88221,847.3 (197.5)0.0222−619.3 (372.0)0.100.75
    Calcium + vitamin D232,347.8 (193.2)0.96212,642.6 (202.1)0.6421146.5 (264.8)0.701.06
Upper 40% of crypts
    Placebo22677.7 (64.1)21655.9 (67.0)2101.00
    Calcium23704.7 (64.1)0.7721525.1 (67.0)0.1721−157.8 (125.8)0.210.77
    Vitamin D23684.4 (64.1)0.9422505.9 (65.5)0.1122−156.8 (125.0)0.210.76
    Calcium + vitamin D23655.0 (64.1)0.8021741.5 (67.0)0.3721108.3 (125.8)0.391.17
Lower 60% of crypts
    Placebo221,418.7 (112.0)211,459.7 (117.2)2101.00
    Calcium231,431.8 (112.0)0.93211,201.5 (117.2)0.1221−271.3 (213.5)0.210.82
    Vitamin D231,450.7 (112.0)0.84221,145.1 (114.5)0.0622−346.6 (212.1)0.110.77
    Calcium + vitamin D231,390.0 (112.0)0.86211,556.8 (117.2)0.5621125.8 (213.5)0.561.09
  • *Absolute treatment effect = [(treatment group follow-up) − (treatment group baseline)] − [(placebo group follow-up) − (placebo group baseline)].

  • Relative effect = [(treatment group follow-up) / (treatment group baseline)] / [(placebo follow-up) / (placebo baseline)]; interpretation similar to that for an odds ratio (e.g., a relative effect of 1.7 indicates a proportional increase of 70% in the treatment group relative to that in the placebo group.

  • P value for difference between each active treatment group and placebo group from repeated-measures MIXED model.

  • §Biomarker was detected immunohistochemically and then its labeling optical density was quantified by image analysis (see text for details).