Table 3

Logistic regression predictive models results by using changes in biomarker levels from baseline to week 4 and clinical response at week 14. Model included training and test datasets combined

ACR 20


CRP-only modela (n = 308)


True/Predicted

NR

R

Accuracy

NR

35

115

Specificity = 23%

R

16

142

Sensitivity = 90%

Predictive value

NPV = 68%

PPV = 55%

Threshold = -0.35


Biomarker modela (n = 308)


True/Predicted

NR

R

Accuracy

NR

62

88

Specificity = 41%

R

16

142

Sensitivity = 90%

Predictive value

NPV = 79%

PPV = 61%


Threshold = -0.35


Predictors from biomarker modelb

Weight

Odds ratio

Multivariate P value


Hyaluronic acid

0.60

1.82

0.0001

Apolipoprotein C3

-0.98

0.38

0.003

Rheumatoid factor positive at baseline

-0.91

0.4

0.014

Basic fibroblast growth factor

0.72

2.05

0.023

Interleukin-16

0.83

2.29

0.031

Interleukin-6 serum

0.21

1.23

0.049

C-reactive protein

0.17

1.19

0.062


ACR 50


CRP-only modela (n = 308)


True/Predicted

NR

R

Accuracy

NR

108

116

Specificity = 48%

R

17

67

Sensitivity = 80%

Predictive Value

NPV = 86%

PPV = 36%

Threshold = -1.3


Biomarker modela (n = 308)


True/Predicted

NR

R

Accuracy

NR

137

87

Specificity = 61%

R

17

67

Sensitivity = 80%

Predictive value

NPV = 89%

PPV = 44%

Threshold = -1.2


Predictors from biomarker modelb

Weight

Odds ratio

Multivariate P value


Hyaluronic acid

0.53

1.70

0.001

Haptoglobin

0.79

2.2

0.001

Apolipoprotein C3

-0.94

0.39

0.007

Interleukin-16

1

2.72

0.014

STJC at baseline

0.17

1.19

0.015

Anti-CCP antibodies

-0.82

0.44

0.044


aAll biomarker values were log transformed before inclusion in the models. Model accuracy (sensitivity, specificity, NPV, PPV) was estimated by using cross validation. bWeights are the coefficients in the logistic regression model. Odds ratios are the exponential of the weights. Multivariate P values are the P values when all of the terms are included in the model. ACR, American College of Rheumatology; anti-CCP, cyclic citrullinated peptide; CRP, C-reactive protein; NPV, negative predictive value; NR, nonresponder; PPV, positive predictive value; R, responder; STJC, swollen and tender joint count.

Visvanathan et al. Arthritis Research & Therapy 2010 12:R211   doi:10.1186/ar3188

Open Data