Table 3.

Association of treatment assignment with recurrent colorectal adenoma risk in the posttreatment observational follow-up phase (N = 1,121)

Any adenomaAdvanced adenomaHigh-risk findingsa
Treatment assignmentNo. of patients/total No. (%)Adjusted relative risk (95% CI)bNo. of patients/total No. (%)Adjusted relative risk (95% CI)bNo. of patients/total No. (%)Adjusted relative risk (95% CI)b
Total N569/1,108 (51.4)104/1,113 (9.3)216/1,096 (19.7)
Vitamin D vs. no vitamin D
 No vitamin D275/552 (49.8)Ref45/552 (8.2)Ref103/545 (18.9)Ref
 Vitamin D294/556 (52.9)1.04 (0.93–1.17)59/561 (10.5)1.30 (0.89–1.88)113/551 (20.5)1.05 (0.83–1.34)
Calcium vs. no calcium
 No calcium238/421 (56.5)Ref40/421 (9.5)Ref87/413 (21.1)Ref
 Calcium231/429 (53.9)0.95 (0.84–1.08)45/433 (10.4)1.07 (0.71–1.61)91/425 (21.4)1.01 (0.77–1.31)
Calcium plus vitamin D vs. calcium
 Calcium158/342 (46.2)Ref25/344 (7.3)Ref60/340 (17.7)Ref
 Calcium plus vitamin D173/345 (50.1)1.07 (0.91–1.25)39/348 (11.2)1.55 (0.97–2.49)69/343 (20.1)1.11 (0.81–1.51)
Calcium plus vitamin D vs. neither
 Neither117/210 (55.7)Ref20/208 (9.6)Ref43/205 (21.0)Ref
 Calcium plus vitamin D119/219 (54.3)0.96 (0.81–1.15)27/221 (12.2)1.22 (0.69–2.13)50/217 (23.0)1.05 (0.72–1.52)
  • NOTE: Analyses of no vitamin D vs. vitamin D included all randomized participants; analyses of calcium vs. no calcium and of both agents vs. neither agent were restricted to full factorial participants; analyses of calcium vs. both agents excluded full factorial participants randomized to placebo or vitamin D alone.

  • aHigh-risk findings include advanced adenomas and/or ≥2 adenomas.

  • bAdjusted for age, clinical center, anticipated surveillance interval (3 or 5 years), three-level variable for sex and randomization arm (male, two-arm female, full factorial female), number of baseline adenomas (0, 1, 2+).