Table 1 ROB of retrospective observational studies with MINORS [18]

Clearly stated aim

1

1

2

2

1

2

2

2

1

Inclusion of consecutive patients

2

2

2

2

2

2

2

2

2

Prospective collection of data

2

1

2

2

2

2

2

1

2

Endpoints appropriate to aim of study

1

2

2

1

1

2

2

2

2

Unbiased assessment of the study endpoint

1

0

1

1

1

1

2

0

0

Follow-up period appropriate to aim of study

2

1

2

2

2

2

2

2

2

Loss to follow up less than 5%

2

2

2

2

2

2

2

1

2

Prospective calculation of the study size

1

0

0

0

0

0

0

0

0

An adequate control group

1

-

1

1

0

0

1

1

-

Contemporary groups

2

-

2

2

2

2

2

2

-

Baseline equivalence of groups

1

-

1

0

0

0

0

1

-

Adequate statistical analyses

1

-

1

1

0

1

1

1

-

Total

17/24

9/16

18/24

16/24

13/24

16/24

18/24

15/24

10/16