Table 4

Sensitivity and specificity of aggrecan fragment measurements

Assay

Cut-off

AUC

Sensitivity

Specificity

OA-1 ARGS ELISA

1 pmol ARGS/ml

82%

67%

92%

Alcian blue precipitation

88.5 μg sGAG/ml

63%

40%

92%

1-F21 ELISA

188.5 μg aggrecan/ml

53%

32%

91%

ARGS/sGAG*

5%

83%

65%

96%

*The molar proportion of aggrecan fragments in SF detected as ARGS neoepitope fragments, measured by Alcian blue precipitation and the ARGS ELISA respectively.

Sensitivity = the proportion of positives (diseased) correctly identified by the test.

Specificity = the proportion of negatives (healthy) correctly identified by the test.

AUC = area under receiver operating characteristic (ROC) curve.

Cut-offs were chosen based on ROC curve analysis where the sum of sensitivity and specificity was highest.

Larsson et al. Arthritis Research & Therapy 2009 11:R92   doi:10.1186/ar2735