Skip to main content

Table 2 Predictive algorithm outcomes using the random forest algorithm diagnostic characteristics

From: Protein oxidation, nitration and glycation biomarkers for early-stage diagnosis of osteoarthritis of the knee and typing and progression of arthritic disease

 

Algorithm 1

Algorithm 2

Features

Hyp and MetSO, DT, NFK, 3-NT, CEL, CMA, G-H1, MG-H1, 3DG-H and pentosidine

anti-CCP antibody positivity and MetSO, DT, 3-NT, FL, CML, CEL, CMA, MG-H1, 3DG-H and pentosidine

Comparators

Disease versus control

eOA

eRA

non-RA

Training set cross-validation

 Correct, n

44/46

13/13

6/8

8/12

 Sensitivity

0.92 (0.64–1.00)

0.92 (0.64–1.00)

0.80 (0.44 - 0.97)

0.70 (0.35 - 0.93)

 Specificity

0.91 (0.76–0.98)

0.90 (0.68–0.99)

0.78 (0.56–0.93)

0.65 (0.43–0.84)

 AUROC

0.99 (0.97–1.00)

0.98 (0.96–1.00)

0.91 (0.82–1.00)

0.68 (0.49–0.86)

 Positive predictive value

1.0

1.0

0.60

0.80

 Negative predictive value

0.85

1.0

0.84

0.83

 Positive likelihood ratio

10.2

9.2

3.6

2.0

 Negative likelihood ratio

0.09

0.09

0.26

0.46

Test set cross-validation

 Correct, n

119/134

30/31

22/27

27/39

 Sensitivity

0.89 (0.75–0.97)

0.83 (0.65–0.94)

0.77 (0.6–0.9)

0.72 (0.53–0.86)

 Specificity

0.90 (0.82–0.95)

0.84 (0.73–0.92)

0.76 (0.63–0.86)

0.71 (0.58–0.81)

 AUROC

0.96 (0.93–0.99)

0.93 (0.88–0.98)

0.87 (0.8–0.94)

0.77 (0.68–0.86)

 Positive predictive value

0.96

0.97

0.81

0.69

 Negative predictive value

0.75

1.0

0.81

0.91

 Positive likelihood ratio

8.9

5.2

3.2

2.5

 Negative likelihood ratio

0.12

0.20

0.30

0.39

Test set validation

 Correct, n

63/134

18/19

8/35

31/32

 Sensitivity

0.73 (0.56–0.86)

0.83 (0.65–0.94)

0.60 (0.42–0.76)

0.81 (0.64–0.93)

 Specificity

0.72 (0.62–0.81)

0.84 (0.73–0.92)

0.61 (0.46–0.72)

0.80 (0.68–0.89)

 AUROC

0.77 (0.69–0.85)

0.91 (0.84–0.99)

0.62 (0.5–0.75)

0.84 (0.77–0.92)

 Positive predictive value

0.62

0.60

0.23

0.97

 Negative predictive value

0.05

0.99

0.97

0.43

 Positive likelihood ratio

2.6

5.2

1.5

4.1

 Negative likelihood ratio

0.38

0.20

0.67

0.24

  1. The 95 % CI for sensitivity and specificity are given in brackets. eOA early osteoarthritis, aOA advanced osteoarthritis, eRA early rheumatoid arthritis, aRA advanced rheumatoid arthritis, CML Nε-carboxymethyl-lysine, CEL Nε-carboxyethyl-lysine, MetSO methionine sulfoxide, DT dityrosine, FL Nε-fructosyl-lysine, MG-H1 methylglyoxal-derived hydroimidazolone, 3DG-H 3-deoxyglucosone-derived hydroimidazolone isomers, NFK N-formylkynurenine, 3-NT 3-nitrotyrosine, G-H1 glyoxal-derived hydroimidazolone, CMANω-carboxymethylarginine