Baseline characteristics of study populations
| US 4 | UK 10 | TPT 5 | HOT 6 | |
| Number | 22071 | 5139 | 2540 | 18790 |
| Aspirin | 11037 | 3429 | 1268 | 9399 |
| Placebo | 11034 | 1710 | 1272 | 9391 |
| Aspirin dose (mg/day) | 162.5 | 500 | 75 | 75 |
| Trial duration (years) | 5.0 | 6.0 | 6.8 | 3.8 |
| Male (%) | 100 | 100 | 100 | 53 |
| Mean age (years) | NA | NA | 57.5 | 61.5 |
| < 60 years (%) | 75 | 47 | NA | NA |
| Smokers (%) | 11 | 13 | 41 | 16 |
| Hypertension (%) | 9 | 10 | 26 | 100 |
| Diabetes mellitus (%) | 2 | 2 | NA | 8 |
NA, not available.