Table 4.

Methodological items for non-randomized studies

Study	Ilchmann 1998	Kolling 2003	Sanders 2011
1. A clearly stated aim	2	2	2
2. Inclusion of consecutive patients	2	2	2
3. Prospective collection of data	0	2	0
4. Endpoints appropriate to the aim of the study	2	2	2
5. Unbiased assessment of the study endpoint	0	0	2
6. Follow-up period appropriate to the aim of the study	2	2	2
7. Loss to follow up less than 5%	0	0	0
8. Prospective calculation of the study size	0	0	0
9. An adequate control group	2	2	2
10. Contemporary groups	2	2	2
11. Baseline equivalence of groups	2	2	2
12. Adequate statistical analyses	2	2	2
Total score	16	18	18