Table 1.

Characteristics of posttreatment observational follow-up phase participants

All participants consented to observational phaseParticipants with observational phase adenoma outcome data
Treatment assignment
Full factorial randomizationTwo-group randomizationa
OverallPlaceboCalciumVitamin DCalcium + vitamin DCalcium + placeboCalcium + vitamin D
Baseline characteristicsN (%) or mean ± SDN (%) or mean ± SDN (%) or mean ± SDN (%) or mean ± SDN (%) or mean ± SDN (%) or mean ± SDN (%) or mean ± SDN (%) or mean ± SD
N1,9861,121210215213224132127
Sex
 Female715 (36.0)375 (33.5)25 (11.9)28 (13.0)28 (13.2)35 (15.6)132 (100)127 (100)
 Male1,271 (64.0)746 (66.6)185 (88.1)187 (87.0)185 (86.9)189 (84.4)00
Age (years)58.1 ± 6.757.8 ± 6.458.3 ± 6.758.5 ± 6.757.6 ± 6.658.1 ± 6.457.2 ± 5.656.3 ± 6.1
Race
 Caucasian1,708 (89.4)975 (89.8)189 (92.2)186 (87.7)194 (94.2)200 (90.1)102 (84.3)104 (86.7)
 African American138 (7.2)83 (7.6)14 (6.8)17 (8.0)7 (3.4)20 (9.0)13 (10.7)12 (10.0)
 Asian/Pacific Islander48 (2.5)20 (1.8)1 (0.5)5 (2.4)4 (1.9)1 (0.5)6 (5.0)3 (2.5)
 Other17 (0.9)8 (0.7)1 (0.5)4 (1.9)1 (0.5)1 (0.5)01 (0.8)
BMI (kg/m2)28.9 ± 5.129.0 ± 5.029.1 ± 4.929.6 ± 5.029.1 ± 4.428.6 ± 4.628.8 ± 5.928.3 ± 5.4
 <25459 (23.1)242 (21.6)39 (18.6)33 (15.4)36 (16.9)51 (22.8)39 (29.6)44 (34.7)
 25–29.9818 (41.2)471 (42.0)95 (45.2)97 (45.1)95 (44.6)99 (44.2)43 (32.6)42 (33.1)
 ≥30708 (35.7)408 (36.4)76 (36.2)85 (39.5)82 (38.5)74 (33.0)50 (37.9)41 (32.3)
Alcohol intake (drinks/day)0.78 ± 1.010.79 ± 1.020.89 ± 1.110.88 ± 1.040.92 ± 1.110.94 ± 1.110.31 ± 0.520.53 ± 0.69
End-of-treatment characteristics
Smoking status
 Never1,061 (53.4)578 (51.6)87 (41.4)112 (52.1)102 (47.9)110 (49.1)88 (66.7)79 (62.2)
 Former805 (40.5)471 (42.0)112 (53.3)91 (42.3)103 (48.4)94 (42.0)37 (28.0)34 (26.8)
 Current120 (6.0)72 (6.4)11 (5.2)12 (5.6)8 (3.8)20 (8.9)7 (5.3)14 (11.0)
 Dietary calcium intake (mg/day)814 ± 140817 ± 138850 ± 132854 ± 149834 ± 120843 ± 133720 ± 109725 ± 103
 Dietary vitamin D intake (IU/day)74 ± 7075 ± 7182 ± 7781 ± 7370 ± 6877 ± 6968 ± 6964 ± 66
Supplemental calciumb (mg/day)
 <4001,887 (95.6)1,062 (95.0)201 (96.2)210 (97.7)201 (94.4)215 (96.9)121 (92.4)114 (89.8)
 ≥40086 (4.4)55 (4.9)8 (3.8)5 (2.3)12 (5.6)7 (3.2)10 (7.6)13 (10.2)
Supplemental vitamin D (IU/day)
 <4001,679 (85.1)961 (86.0)190 (90.9)185 (86.1)183 (85.9)196 (88.3)107 (81.7)100 (78.7)
 ≥400294 (14.9)156 (14.0)19 (9.1)30 (14.0)30 (14.1)26 (11.7)24 (18.3)27 (21.3)
 Serum 25-hydroxy-vitamin D (ng/mL)c29.1 ± 10.428.6 ± 10.324.1 ± 8.324.6 ± 9.031.3 ± 8.833.6 ± 10.925.0 ± 9.833.2 ± 10.1
Aspirin use
 <4 days/week1,074 (54.7)611 (54.9)107 (51.4)101 (47.2)105 (49.3)117 (52.7)89 (67.9)92 (73.0)
 ≥4 days/week890 (45.3)503 (45.2)101 (48.6)113 (52.8)108 (50.7)105 (47.3)42 (32.1)34 (27.0)
NSAID use (nonaspirin)
 <4 days/week1,755 (89.8)1,006 (90.6)188 (90.4)199 (93.0)190 (90.1)204 (92.3)109 (83.9)116 (91.3)
 ≥4 days/week199 (10.2)105 (9.5)20 (9.6)15 (7.0)21 (10.0)17 (7.7)21 (16.2)11 (8.7)
Adenoma at end-of-treatment colonoscopy
 No1,115 (57.3)587 (53.4)112 (54.1)108 (51.4)97 (46.6)114 (51.8)81 (62.8)75 (60.0)
 Yes830 (42.7)512 (46.6)95 (45.9)102 (48.6)111 (53.4)106 (48.2)48 (37.2)50 (40.0)
Advanced adenoma at end-of-treatment colonoscopy
 No1,775 (90.6)974 (88.1)183 (88.8)181 (85.4)181 (86.2)197 (88.3)120 (92.3)112 (89.6)
 Yes185 (9.4)132 (11.9)23 (11.2)31 (14.6)29 (13.8)26 (11.7)10 (7.7)13 (10.4)
  • NOTE: Numbers for some characteristics may not sum to total N due to missing data.

  • Abbreviations: SD, standard deviation; BMI, body mass index.

  • aParticipants not randomized to calcium but were given calcium; offered to women who wanted to take calcium.

  • bSupplemental values in elemental mg/day and include separate supplements and multivitamins. Participants were asked to cease these supplements at enrollment as a condition of study entry.

  • cSeasonally adjusted serum 25(OH) vitamin D concentration.