Anti-dsDNA-NcX ELISA: dsDNA-loaded nucleosomes improve diagnosis and monitoring of disease activity in systemic lupus erythematosus

Table 1 Performance criteria in ROC analysis^a

Criteria	Anti-dsDNA-NcX	Anti-dsDNA	Antinucleosome	Farr
Area under the curve	0.9133^b	0.8455	0.9118	0.8823
95% confidence interval	0.89 to 0.94	0.81 to 0.88	0.89 to 0.94	0.85 to 0.91
Sensitivity at specificity of 95%	72.5%^b	55.6%	67.2%	65.7%
(cutoff)	(>49.7)	(>58.8)	(>6.8)	(>5.1)
Sensitivity at specificity of 98%	66.7%^b	43.0%	58.0%	55.6%
(cutoff)	(>71.5)	(>99.7)	(>11.1)	(>6.0)
Sensitivity at specificity of 98.15%^c	66.7%^b	41.5%	55.6%	55.6
(cutoff)	(>72.03)	(>105.8)	(>12.1)	(>6.0)
Sensitivity at specificity of 99%	59.9%^b	35.8%	53.6%	54.1%
(cutoff)	(>103.4)	(>151.6)	(>14.8)	(>6.5)
Maximum sum of sensitivity + specificity	170.9^b	159.1	168.7	162.1

^adsDNA, double-stranded DNA. Test criteria for the Anti-dsDNA-NcX, anti-dsDNA and antinucleosome enzyme-linked immunosorbent assays (ELISAs), as well as for the anti-dsDNA radioimmunoassay (also known as a Farr assay), were calculated using receiver operating characteristic (ROC) curve analysis based on test readings of 964 samples from 207 systemic lupus erythematosus (SLE) patients, 357 disease controls and 400 healthy donors. Outcome parameters of ROC curve analysis were diagnosis versus no diagnosis of SLE. ^bHighest value over all four assays. ^cThis specificity was calculated for the Crithidia luciliae immunofluorescence (CLIF) assay.

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