1. A clearly stated aim | 2 | 2 | 2 | 2 | 2 | 2 |
2. Inclusion of consecutive patients | 2 | 2 | 2 | 2 | 2 | 2 |
3. Prospective collection of data | 2 | 0 | 2 | 0 | 2 | 0 |
4. End points appropriate to the aim of the study | 2 | 2 | 2 | 2 | 2 | 2 |
5. Unbiased assessment of the study end point | 0 | 0 | 0 | 0 | 0 | 0 |
6. Follow-up period appropriate to the aim of the study | 2 | 2 | 2 | 2 | 2 | 2 |
7. Loss to follow-up less than 5% | 0 | 0 | 1 | 0 | 0 | 0 |
8. Prospective calculation of the study size | 0 | 0 | 0 | 0 | 0 | 0 |
9. An adequate control group | 2 | 2 | 2 | 2 | 2 | 2 |
10. Contemporary groups | 2 | 2 | 2 | 2 | 2 | 2 |
11. Baseline equivalence of groups | 2 | 2 | 2 | 2 | 2 | 2 |
12. Adequate statistical analyses | 2 | 2 | 2 | 2 | 2 | 2 |