TABLE 2.
Baseline characteristics of participants in 5 case-control studies nested within the Alpha-Tocopherol, Beta-Carotene Cancer Prevention Study1
| Characteristic | Total (n = 1336) | Controls (n = 837) | Cases (n = 499) | P2 | P3 |
| Age at blood draw, y | 57 (54–62) | 58 (54–62) | 57 (53–61) | 0.19 | <0.0001 |
| BMI, kg/m2 | 26 (24–28) | 26 (24–28) | 26 (24–28) | 0.31 | 0.93 |
| Smoked regularly, y | 37 (32–42) | 37 (31–42) | 37 (32–42) | 0.89 | 0.02 |
| Cigarettes smoked/d,4 n | 20 (15–25) | 20 (15–25) | 20 (15–25) | 0.034 | 0.02 |
| Daily energy intake, kcal/d | 2610 (2152–3094) | 2622 (2179–3094) | 2593 (2135–3102) | 0.38 | 0.23 |
| Education | |||||
| Less than elementary | 1053 (79) | 671 (80) | 382 (77) | 0.12 | 0.87 |
| At least elementary | 283 (21) | 166 (20) | 117 (23) | ||
| Leisure-time physical activity | |||||
| Light | 510 (38) | 317 (38) | 193 (39) | 0.77 | 0.007 |
| Moderate or heavy | 826 (62) | 520 (62) | 306 (61) | ||
| Occupational physical activity | |||||
| Nonworking | 575 (43) | 358 (43) | 217 (43) | 0.43 | 0.07 |
| Sedentary | 204 (15) | 119 (14) | 85 (17) | ||
| Light | 235 (18) | 154 (18) | 81 (16) | ||
| Moderate or heavy | 322 (24) | 206 (25) | 116 (23) | ||
Values are medians (IQRs) or n (%). Cases and controls obtained from 5 nested studies are the following: 1) esophageal cancer, n = 64 controls and 69 cases, 2) pancreatic cancer, n = 114 controls and 115 cases, 3) pancreatic and lung cancer, n = 146 controls and 175 cases, 4) pancreatic cancer, n = 326 controls and 140 cases, and 5) prostate cancer, n = 187 controls only.
Comparison of cases and controls. Wilcoxon’s Signed Rank test for continuous variables and chi-square or Fisher’s exact test for categorical variables.
Comparison across 5 nested studies. Kruskal-Wallis test for continuous variables and chi-square or Fisher’s exact test for categorical variables comparing differences across the 5 nested case-control studies.
Mean number of cigarettes smoked per day was 19.5 for controls and 20.5 for cases. Data were not normally distributed.