Table 2.
Folic acid treatment at 1mg/day and risk of any adenomas and advanced lesions by baseline dietary, total intake, plasma and RBC folate levels§
| 1st Follow-up | 2nd Follow-up | |||||||
|---|---|---|---|---|---|---|---|---|
| Placebo (n=486) | Folic Acid (n= 501) | RR (95% CI) | p-value¥ | Placebo (n=373) | Folic Acid (n=403) | RR (95% CI) | p-value¥ | |
| Dietary folate intake† | ||||||||
| Any adenoma | ||||||||
| T1: 63.9-246.1 mcg* | 74(47.1%) | 67(43.2%) | 0.91(0.71-1.17) | 0.13 | 40(34.5%) | 43(34.7%) | 0.99(0.70-1.41) | 0.67 |
| T2: 246.5-352.9 mcg* | 55(36.9%) | 85(50.3%) | 1.30(1.01-1.69) | 44(35.8%) | 53(38.1%) | 1.04(0.76-1.44) | ||
| T3: 353.1-1285.6 mcg* | 70(43.8%) | 64(40.5%) | 0.98(0.76-1.27) | 52(42.6%) | 58(46.0%) | 1.21(0.89-1.65) | ||
| Advanced lesions | ||||||||
| T1: 63.9-246.1 mcg* | 15(9.6%) | 13(8.4%) | 0.88(0.43-1.80) | 0.43 | 10(8.6%) | 11(8.9%) | 0.89(0.38-2.11) | 0.21 |
| T2: 246.5-352.9 mcg* | 12(8.1%) | 24(14.2%) | 1.69(0.87-3.28) | 11(8.9%) | 13(9.4%) | 1.01(0.46-2.21) | ||
| T3: 353.1-1285.6 mcg* | 15(9.4%) | 19(12.0%) | 1.34(0.70-2.58) | 8(6.6%) | 17(13.5%) | 2.38(1.03-5.48) | ||
| Total folate intake† | ||||||||
| Any adenoma | ||||||||
| T1: 67.3-303.9 mcg* | 78(50.7%) | 73(45.1%) | 0.85(0.67-1.09) | 0.01 | 40(35.1%) | 45(34.9%) | 0.97(0.69-1.36) | 0.71 |
| T2: 304.5-551.3 mcg* | 62(42.5%) | 72(42.1%) | 0.99(0.76-1.28) | 45(37.2%) | 59(43.1%) | 1.18(0.86-1.61) | ||
| T3: 552.0-1807.8 mcg* | 59(35.5%) | 71(47.7%) | 1.46(1.12-1.89) | 51(40.5%) | 50(40.7%) | 1.09(0.79-1.50) | ||
| Advanced lesions | ||||||||
| T1: 67.3-303.9 mcg* | 15(9.7%) | 20(12.4%) | 1.30(0.68-2.48) | 0.94 | 9(7.9%) | 9(7.0%) | 0.87(0.35-2.17) | 0.58 |
| T2: 304.5-551.3 mcg* | 14(9.6%) | 21(12.3%) | 1.17(0.61-2.25) | 9(7.4%) | 16(11.7%) | 1.43(0.63-3.23) | ||
| T3: 552.0-1807.8 mcg* | 13(7.8%) | 15(10.1%) | 1.39(0.68-2.85) | 11(8.7%) | 16(13.0%) | 1.61(0.74-3.48) | ||
| Plasma folate‡ | ||||||||
| Any adenoma | ||||||||
| T1: 2.4-13.6 nmol/L | 70(46.1%) | 70(47.0%) | 0.98(0.76-1.27) | 0.40 | 46(38.3%) | 55(43.7%) | 1.17(0.86-1.60) | 0.77 |
| T2: 13.6-26.7 nmol/L | 62(42.8%) | 69(44.0%) | 1.02(0.78-1.33) | 45(38.1%) | 50(37.6%) | 1.01(0.73-1.40) | ||
| T3: 26.7-159.9 nmol/L | 55(36.9%) | 66(43.7%) | 1.26(0.58-2.42) | 45(38.8%) | 45(38.5%) | 1.02(0.73-1.43) | ||
| Advanced lesions | ||||||||
| T1: 2.4-13.6 nmol/L | 13(8.6%) | 15(10.1%) | 1.18(0.58-2.42) | 0.35 | 11(9.2%) | 15(11.9%) | 1.31(0.61-2.80) | 0.93 |
| T2: 13.6-26.7 nmol/L | 13(9.0%) | 15(9.6%) | 1.02(0.50-2.10) | 7(5.9%) | 15(11.3%) | 1.52(0.63-3.69) | ||
| T3: 26.7-159.9 nmol/L | 11(7.4%) | 22(14.6%) | 2.06(1.02-4.16) | 11(9.5%) | 12(10.3%) | 1.21(0.53-2.76) | ||
| RBC folate‡ | ||||||||
| Any adenoma | ||||||||
| T1: 64.9-338.0 ng/ml | 68(45.3%) | 81(45.0%) | 0.95(0.74-1.21) | 0.60 | 32(29.6%) | 56(39.2%) | 1.31(0.92-1.85) | 0.50 |
| T2: 339.0-449.0 ng/ml | 73(42.4%) | 68(43.6%) | 1.06(0.82-1.36) | 53(39.6%) | 49(36.8%) | 1.00(0.73-1.37) | ||
| T3: 450.0-1133.0 ng/ml | 64(39.5%) | 71(43.6%) | 1.14(0.88-1.47) | 56(43.4%) | 55(44.0%) | 1.04(0.77-1.40) | ||
| Advanced lesions | ||||||||
| T1: 64.9-338.0 ng/ml | 10(6.7%) | 18(10.0%) | 1.45(0.69-3.05) | 0.92 | 7(6.5%) | 17(11.9%) | 1.74(0.73-4.14) | 0.79 |
| T2: 339.0-449.0 ng/ml | 11(6.4%) | 13(8.3%) | 1.37(0.63-2.96) | 7(5.2%) | 10(7.5%) | 1.57(0.61-4.01) | ||
| T3: 450.0-1133.0 ng/ml | 21(13.0%) | 26(16.0%) | 1.21(0.70-2.11) | 15(11.6%) | 18(14.4%) | 1.20(0.61-2.37) | ||
†
Adjusted for age, sex, center, duration of follow-up, aspirin treatment group, multivitamin use and log calories;
‡
Adjusted for age, sex, center, duration of follow-up, multivitamin use, aspirin treatment group;
*
Ranges are based on 2000 calories/day;
¥
p-value for heterogeneity;
§
counts do not necessarily add to the total sum due to missing data.