Table I.
Baseline characteristics of cohort participants by amount of caffeine consumed
| Amount of daily intake |
||||
|---|---|---|---|---|
| Characteristic | <50 mg | 50 to <250 mg | 250 to <400 mg | ≥400 mg |
| Participants, n | 10,330 | 42,361 | 6634 | 1996 |
| Skin cancer cases, n | 124 | 421 | 50 | 14 |
| Mean age at recruitment ± SD, y | 56.9 ± 8.4 | 56.4 ± 8.0 | 55.7 ± 7.6 | 55.5 ± 7.5 |
| Men, n (%) | 3378 (32.7) | 18,518 (43.7) | 4037 (60.8) | 1360 (68.1) |
| Dialect, n (%) | ||||
| Cantonese | 4749 (46.0) | 19631 (46.3) | 3142 (47.4) | 803 (40.3) |
| Hokkein | 5581 (54.0) | 22,730 (53.7) | 3492 (52.6) | 1193 (59.7) |
| Secondary school or higher, n (%) | 2977 (28.8) | 11,818 (27.9) | 2037 (30.7) | 604 (30.3) |
| Ever-smoker, n (%) | 1844 (17.9) | 12,729 (30.0) | 2969 (44.7) | 1196 (60.0) |
| Mean BMI, kg/m2 | 23.0 ± 3.3 | 23.2 ± 3.2 | 23.2 ± 3.4 | 23.1 ± 3.4 |
| Mean time sitting at work ± SD, h/d | 0.83 ± 1.3 | 0.92 ± 1.3 | 1.02 ± 1.4 | 1.03 ± 1.4 |
| Mean time watching television ± SD, h/d | 2.25 ± 0.9 | 2.26 ± 0.9 | 2.21 ± 0.9 | 2.18 ± 0.9 |
| Mean time engaging in moderate activity ± SD, h/wk | 0.99 ± 2.7 | 0.82 ± 2.5 | 0.99 ± 2.8 | 0.83 ± 2.7 |
| Mean time engaging in vigorous activity ± SD, h/wk | 0.31 ± 2.3 | 0.50 ± 3.1 | 0.98 ± 4.3 | 1.06 ± 4.4 |
| Mean time engaging in strenuous sports ± SD, h/wk | 0.18 ± 1.0 | 0.17 ± 1.0 | 0.24 ± 1.2 | 0.21 ± 1.1 |
| Diabetes, n (%) | 1158 (11.2) | 3689 (8.7) | 492 (7.4) | 130 (6.5) |
| Alcohol intake, n (%) | ||||
| Nondrinker | 9690 (93.8) | 37,346 (88.2) | 5464 (82.4) | 1644 (82.4) |
| Weekly drinker | 466 (4.5) | 3451 (8.1) | 851 (12.8) | 250 (12.5) |
| Daily drinker | 174 (1.7) | 1564 (3.7) | 319 (4.8) | 102 (5.1) |
| Mean coffee intake ± SD, cups/wk | 0.5 ± 0.9 | 9.5 ± 5.9 | 18.7 ± 7.5 | 31.5 ± 9.5 |
| Mean green tea ± SD, cups/wk | 0.4 ± 0.8 | 1.7 ± 4.2 | 6.6 ± 10.2 | 6.9 ± 12.5 |
| Mean black tea intake ± SD, cups/wk | 0.4 ± 1.0 | 1.5 ± 3.5 | 3.4 ± 5.9 | 2.8 ± 7.0 |
| Mean soda intake ± SD, glasses/wk | 0.3 ± 1.0 | 0.5 ± 1.9 | 1.2 ± 3.4 | 1.4 ± 3.8 |
P values are based on chi-square test for categoric variables and 1-way analysis of variance for continuous variables; all P values <.0001. BMI, Body mass index; SD, standard deviation.