Table 4 Sensitivity, specificity, and likelihood ratios for persistent arthritis for different minimum cut-off levels for anti-CCP2 and IgM RF

2

0.71

0.55

0.63

1.59 (1.32 to 1.91)

0.53 (0.41 to 0.69)

3

0.58

0.72

0.65

2.06 (1.60 to 2.65)

0.58 (0.48 to 0.71)

4

0.47

0.80

0.65

2.38 (1.73 to 3.27)

0.66 (0.56 to 0.77)

5

0.43

0.87

0.67

3.23 (2.18 to 4.77)

0.66 (0.57 to 0.77)

10

0.35

0.93

0.66

4.98 (2.88 to 8.58)

0.71 (0.69 to 1.79)

15

0.32

0.95

0.66

5.91 (3.20 to 10.92)

0.72 (0.64 to 0.80)

20

0.31

0.95

0.65

5.59 (3.02 to 10.37)

0.74 (0.66 to 0.82)

25

0.30

0.95

0.64

6.04 (3.17 to 11.51)

0.74 (0.67 to 0.82)

Cut-off IgM RF

(units/ml)

Sensitivity

Specificity

Accuracy

LR+

LR-

2

0.71

0.41

0.55

1.20 (1.04 to 1.39)

0.71 (0.53 to 0.94)

3

0.62

0.54

0.58

1.34 (1.13 to 1.65)

0.70 (0.55 to 0.88)

5

0.51

0.69

0.61

1.67 (1.30 to 2.15)

0.71 (0.59 to 0.84)

7

0.43

0.77

0.61

1.85 (1.37 to 2.51)

0.74 (0.64 to 0.86)

10

0.33

0.87

0.62

2.49 (1.66 to 3.76)

0.77 (0.68 to 0.87)

15

0.31

0.92

0.64

3.69 (2.22 to 6.12)

0.75 (0.68 to 0.84)

20

0.29

0.95

0.64

5.28 (2.84 to 9.81)

0.75 (0.68 to 0.83)

25

0.28

0.95

0.64

5.69 (2.97 to 10.89)

0.76 (0.69 to 0.83)