Table 1.
Baseline characteristics of women with follow-up endoscopies by treatment assignment with combined folic acid, vitamin B6, vitamin B12 treatment vs placebo in the Women’s Antioxidant and Folic Acid Cardiovascular Study (WAFACS)
| Characteristics | Folic acid, vitamin B6, and vitamin B12 (n=741) | Placebo (n=729) | P* |
|---|---|---|---|
| Mean age, y (SD) | 62.1 (7.6) | 61.8 (7.6) | .54 |
| Mean body mass index (SD), kg/m2 | 30.6 (6.4) | 30.1 (6.0) | .09 |
| Smoking status, no. (%) | |||
| Current | 56 (7.6) | 55 (7.5) | .47 |
| Past | 328 (44.3) | 340 (46.6) | |
| Never | 357 (48.2) | 334 (45.8) | |
| Mean alcohol intake (SD), g/d | 3.2 (7.5) | 3.6 (7.7) | .16 |
| Mean physical activity, kcal/wk, no. (%) | |||
| <1000 | 445 (60.1) | 437 (59.9) | .97 |
| ≥1000 | 296 (39.9) | 292 (40.1) | |
| Menopausal status, no. (%) | |||
| Premenopausal | 41 (5.5) | 46 (6.3) | .17 |
| Uncertain | 23 (3.1) | 10 (1.4) | |
| Postmenopausal | 677 (91.4) | 673 (92.3) | |
| Postmenopausal hormone use, no. among postmenopausal women only (%) | |||
| Current | 426 (62.9) | 434 (64.5) | .59 |
| Past | 112 (16.5) | 107 (15.9) | |
| Never | 139 (20.5) | 132 (19.6) | |
| Baseline dietary intake | |||
| Total folate, mean (SD) µg† | 516.3 (259.6) | 515.0 (234.5) | .66 |
| Total vitamin B6, mean (SD), mg† | 5.1 (15.2) | 5.6 (17.4) | .99 |
| Total vitamin B12, mean (SD), µg† | 9.3 (11.4) | 9.5 (9.5) | .54 |
| Red meat (servings/d) | 0.8 (0.6) | 0.8 (0.6) | .20 |
| Processed meat (servings/d) | 0.1 (0.2) | 0.1 (0.2) | .82 |
| Methionine, mean (SD), g/d† | 1.9 (0.6) | 2.0 (0.7) | .65 |
| Baseline plasma concentrations | |||
| Folate, mean (SD), ng/mL | 13.1 (8.3) | 13.9 (8.9) | .29 |
| Vitamin B6, mean (SD), pmol/mL | 65.8 (58.7) | 61.3 (50.5) | .24 |
| Vitamin B12, mean (SD), pg/mL | 490.5 (227.7) | 494.2 (216.9) | .48 |
| Homocysteine, mean (SD), nmol/mL | 11.0 (4.2) | 11.1 (4.1) | .89 |
| Cysteine, mean (SD), nmol/mL | 277.8 (49.2) | 274.9 (49.9) | .37 |
| Cysteinylglycine, mean (SD), nmol/mL | 345.6 (184.6) | 346.6 (150.6) | .59 |
| Current multivitamin use before random assignment, no. (%) | |||
| Yes | 188 (25.4) | 176 (24.1) | .59 |
| No | 553 (74.6) | 553 (75.9) | |
| CVD health history, no. (%)‡ | |||
| Previous CVD | 461 (62.2) | 440 (60.4) | .47 |
| ≥Three risk factors | 280 (37.8) | 289 (39.6) | |
| History of cancer within past 10 years except nonmelanoma skin cancers, no. (%) | |||
| Yes | 38 (5.1) | 50 (6.9) | .16 |
| No | 703 (94.9) | 679 (93.1) | |
| History of diabetes, no. (%) | |||
| Yes | 120 (16.2) | 94 (12.9) | .07 |
| No | 621 (83.8) | 635 (87.1) | |
| History of endoscopy before random assignment, no. (%) | |||
| Yes | 119 (16.1) | 120 (16.5) | .83 |
| No | 622 (83.9) | 609 (83.5) | |
| History of any adenoma before random assignment among those with prerandomization endoscopy, no. (%) among those with prerandomization endoscopy | |||
| No adenoma | 77 (64.7) | 91 (75.8) | .43 |
| Early adenoma (small/tubular) | 20 (16.8) | 8 (6.7) | |
| Advanced adenoma (large or villous histology or high-grade dysplasia) | 15 (12.6) | 11 (9.2) | |
| Stage not specified/missing | 7(5.9) | 10 (8.3) | |
| No. of adenomas before random assignment among those with prerandomization endoscopy (%) | |||
| 0 | 77 (64.7) | 91 (75.8) | .09 |
| 1 | 26 (21.9) | 18 (15.0) | |
| 2 | 9 (7.6) | 7 (5.8) | |
| ≥3 | 7 (5.9) | 4 (3.3) | |
| Total no. of endoscopies during follow-up (%)§ | |||
| 1 | 487 (65.7) | 464 (63.7) | .60 |
| 2 | 182 (24.6) | 196 (26.9) | |
| ≥3 | 72 (9.7) | 69 (9.5) | |
| Time between start of trial and endoscopy (mo)§ | |||
| First endoscopy | 52.2 (28.4) | 52.7 (27.9) | .84 |
| Second endoscopy | 75.8 (22.7) | 75.0 (22.5) | .70 |
| Last endoscopy | 71.9 (25.3) | 72.8 (24.5) | .58 |
| No. randomly assigned to receive vitamin E (%) | |||
| Yes | 364 (49.1) | 373 (51.2) | .43 |
| No | 377 (50.9) | 356 (48.8) | |
| No. randomly assigned to receive vitamin C (%) | |||
| Yes | 390 (52.6) | 369 (50.6) | .44 |
| No | 351 (47.4) | 360 (49.4) | |
| No. randomly assigned to receive β-carotene (%) | |||
| Yes | 374 (50.5) | 358 (49.1) | .60 |
| No | 367 (49.5) | 371 (50.9) | |
* Two-sided P values were calculated by using Wilcoxon rank-sum test for continuous variables and Mantel–Haenszel χ2 test for categorical variables. CVD = cardiovascular disease; PMH = postmenopausal hormone.
† The energy-adjusted nutrient intake was calculated.
‡ CVD health history was categorized as women with a self-reported history of myocardial infarction, stroke, coronary revascularization, angina pectoris, transient ischemic attack, carotid endarterectomy, or peripheral artery surgery; or those with no previous CVD but with at least three of the following: hypertension, high cholesterol level, diabetes mellitus, parental history of premature myocardial infarction (before age 60 years), obesity (body mass index ≥30kg/m2), current cigarette smoking, and inconsistent report of previous CVD.
§ Endoscopies performed between May 1, 1998 (the initiation of trial) and June 30, 2007 (≤23 months after completion of the trial) (trial ended on July 31, 2005) were counted as endoscopies performed during the study period.