Table 5.

Prevalent colorectal adenoma outcomes, by subgroup

SeleniumVitamin E
Active number (%)Placebo number (%)RR95% CIPActive number (%)Placebo number (%)RR95% CIP
Colorectal adenoma
 Aspirin
  Nonusers597 (33.5)629 (36.4)0.920.84–1.010.07600 (34.5)626 (35.3)0.970.89–1.070.55
  Users539 (34.9)521 (34.9)1.000.91–1.100.98559 (36.5)501 (33.3)1.101.00–1.210.06
P 3-way = 0.104
P all 2-way = 0.204
 BMI
  Normal206 (30.2)194 (31.4)0.960.82–1.130.62187 (30.2)213 (31.4)0.960.82–1.130.63
  Overweight562 (35.2)578 (36.5)0.970.88–1.060.47596 (36.8)544 (34.9)1.050.96–1.160.26
  Obesea365 (35.2)374 (37.0)1.090.92–1.280.32372 (36.5)367 (35.7)1.160.99–1.370.07
P 3-way = 0.013
P all 2-way = not tested
 FDRs with CRC
  0921 (33.6)937 (35.7)0.940.88–1.010.11963 (35.7)895 (33.5)1.070.99–1.150.09
  ≥1159 (37.2)147 (33.8)1.090.91–1.310.34138 (33.1)168 (37.7)0.880.74–1.060.18
P 3-way = 0.075
P all 2-way = not tested
 Race/ethnicity
  White973 (34.1)992 (35.6)0.960.89–1.030.22994 (35.2)971 (34.4)1.020.95–1.100.59
  African American126 (35.6)119 (34.9)1.030.84–1.260.76130 (37.4)115 (33.1)1.130.92–1.380.24
  Hispanic22 (35.5)21 (38.2)0.930.58–1.490.7625 (40.3)18 (32.7)1.230.76–2.000.40
P 3-way = 0.467
P all 2-way = 0.933
 Age
  <63 years566 (31.6)609 (34.9)0.910.83–1.000.04631 (34.8)544 (31.6)1.101.00–1.210.05
  ≥63 years570 (37.2)541 (36.6)1.010.92–1.110.77528 (36.2)583 (37.5)0.970.88–1.060.45
P 3-way = 0.601
P all 2-way = 0.082
Advanced colorectal neoplasia
 Aspirin
  Nonusers158 (9.0)163 (9.7)0.940.76–1.150.52161 (9.4)160 (9.2)1.020.83–1.260.84
  Users111 (7.4)119 (8.2)0.900.70–1.160.42119 (8.0)111 (7.5)1.060.83–1.360.63
P 3-way = 0.137
P all 2-way = 0.743
 BMI
  Normal44 (6.6)41 (6.8)0.970.64–1.460.8744 (7.2)41 (6.2)1.170.77–1.760.46
  Overweight133 (8.5)146 (9.5)0.900.72–1.130.36141 (9.0)138 (9.1)0.990.79–1.230.91
  Obese92 (9.1)92 (9.3)0.980.74–1.290.8694 (9.5)90 (8.9)1.060.80–1.400.68
P 3-way = 0.870
P all 2-way = 0.578
 FDRs with CRC
  0b213 (7.9)213 (8.3)1.200.92–1.560.18222 (8.4)204 (7.8)1.341.04–1.750.03
  ≥1c39 (9.4)51 (12.0)0.460.26–0.810.0140 (9.8)50 (11.6)0.510.29–0.880.02
P 3-way = 0.001
P all 2-way = not tested
 Race/ethnicity
  White229 (8.2)245 (9.0)0.910.76–1.080.28244 (8.9)230 (8.3)1.060.89–1.260.50
  African American31 (8.9)31 (9.3)0.950.59–1.530.8430 (8.8)32 (9.4)0.940.58–1.510.79
  Hispanic7 (11.5)5 (9.3)1.230.42–3.640.715 (8.2)7 (13.0)0.640.21–1.880.41
P 3-way = 0.672
P all 2-way = 0.870
 Age
  <63 years129 (7.3)146 (8.5)0.860.68–1.080.18138 (7.8)137 (8.1)0.960.76–1.200.70
  ≥63 years140 (9.4)136 (9.5)0.990.79–1.240.91142 (10.0)134 (8.9)1.130.91–1.420.28
P 3-way = 0.494
P all 2-way = 0.371
  • NOTE: Bold signifies a statistically significant effect within the subgroup (P < 0.05)

  • Abbreviations: CRC, colorectal cancer; P 3-way, P from the test of the 3-way interaction term; P all 2-way, P from the simultaneous test of all 2-way interaction terms.

  • aStatistically significant interaction between selenium and vitamin E treatment assignment: RR = 0.77; 95% CI, 0.61–0.97; P = 0.028.

  • bStatistically significant interaction between selenium and vitamin E treatment assignment: RR = 0.65; 95% CI, 0.45–0.94; P = 0.021.

  • cStatistically significant interaction between selenium and vitamin E treatment assignment: RR = 3.14; 95% CI, 1.38–7.13; P = 0.006.