Table 1 Adjustments included in the 12 pooled observational studies into RBC transfusions relationship with mortality

Cardio-vascular comorbidities

6

1

1

9

13

13

43

Demographic/Socio-economic factors

5

2

3

3

2

3

3

4

2

1

5

33

Severity of disease scores

3

3

2

1

1

1

3

1

1

2

18

Other admission adjustments

6

3

1

1

1

12

Perioperative adjustments

3

3

5

11

Tests and procedure results

1

1

3

2

2

1

10

Hemoglobin/Hematocrit

2

2

1

1

1

1

8

Diabetes

1

2

1

1

5

Alcohol/Tobacco use

1

2

2

5

Medication

1

1

3

5

Renal comorbidities

1

1

1

1

4

Smoking status

1

1

2

Blood loss

1

1

2

Family history of disease

1

1

2

Other blood products

2

2

Respiratory comorbidities

1

1

Liver comorbidities

1

1

Pre-operative transfusion

1

1

Age of blood transfused

1

1

Septic shock

1

1

Total

30

3

7

5

18

8

29

9

28

4

4

22

167