Table 1

The effects of anaemia and acidosis on bias and limits of agreement

Haemoglobin concentration (g/dl)

Hydrogen ion concentration (nmol/l)

Total

<8

8–12

>12

25–63

>63

n (measurements)

1132

49

963

120

1064

58

Bias

1.34

2.09*

1.37*

0.72^†‡

1.39

0.38^§

Upper limit

4.97

7.04

4.87

4.37

4.95

4.61

Lower limit

-2.29

-2.79

-2.14

-2.93

-2.18

-3.85

P < 0.01, versus *haemoglobin >12 g/dl, ^†haemoglobin <8 g/dl, ^‡haemoglobin 8–12 g/dl and ^§hydrogen 25–63 nmol/l.

Perkins et al. Critical Care 2003 7:R67   doi:10.1186/cc2339