Diagnostic value and clinical laboratory associations of antibodies against recombinant ribosomal P0, P1 and P2 proteins and their native heterocomplex in a Caucasian cohort with systemic lupus erythematosus

Table 1 Test values of antiribosomal P_NH, P_R0, P_R1 and P_R2 antibodies calculated in receiver-operating characteristics analysis^a

Statistics	aRibP _N H	aRibP _R 0	aRibP _R 1	aRibP _R 2	Anti-Sm	Anti-dsDNA Farr assay	Anti-dsDNA ELISA
Area under curve	0.7014	0.7368^b	0.5811	0.6220	0.6791	0.8463	0.8621
95% CI	0.65 to 0.75	0.69 to 0.79	0.52 to 0.64	0.57 to 0.67	0.62 to 0.74	0.80 to 0.89	0.82 to 0.90
P value	<0.0001	<0.0001	0.0021	<0.0001	<0.0001	<0.0001	<0.0001
Sensitivity at 95% specificity cutoff	24.4% (4.5)	29.2% (2.7)^b	20.4% (6.6)	20.2% (10.5)	38.7% (2.0)	61.4% (5.4)	53.9% (73.9)
Sensitivity at 98% specificity cutoff	19.1% (6.7)	22.0% (3.7)^b	16.1% (8.4)	17.9% (12.1)	33.7% (2.4)	56.4% (6.5)	42.9% (105.8)
Sensitivity at 99% specificity cutoff	14.3% (9.4)	22.0% (4.2)^b	10.7% (13.0)	14.9% (13.9)	19.6% (4.8)	55.8% (6.8)	37.4% (151.0)
Sensitivity at 100% specificity cutoff	11.9 (11.5)^b	11.3% (9.1)	8.9% (14.7)	11.3% (17.4)	12.3% (7.9)	49.1% (9.0)	31.3% (169.0)
Maximum sum of specificity and sensivity	133.2%	140.7%^b	118.2%	117.9%	138.9%	161.8%	160.8%

^aaRibP_NH, antibody against native ribosomal P heterocomplex; aRibP_R0, antibody against recombinant ribosomal P0 protein; aRibP_R1, antibody against recombinant ribosomal P1 protein; aRibP_R2, antibody against recombinant ribosomal P2 protein; anti-Sm, anti-Smith antibody; anti-dsDNA, anti-double-stranded DNA antibody; ELISA, enzyme-linked immunosorbent assay; 95% CI, 95% confidence interval; ^bhighest values of sensitivity, area under the curve and lowest cutoff values (in parentheses) among autoantibodies against ribosomal P protein (aRibP).