Anti-Double-Stranded DNA Isotypes and Anti-C1q Antibody Improve the Diagnostic Specificity of Systemic Lupus Erythematosus

Table 6

Diagnostic value of anti-dsDNA isotypes, anti-C1q antibody, and low C3 and/or C4 for disease activity of SLE.

	Sensitivity	Specificity	PPV	NPV	OR (95% CI)
Anti-dsDNA IgG	83%	46%	69%	64%	4.029 (1.592–10.196)
Anti-dsDNA IgA	42%	80%	75%	48%	2.818 (1.103–7.203)
Anti-C1q	63%	74%	78%	58%	4.971 (2.025–12.202)
Anti-dsDNA IgG and IgA	42%	82%	77%	49%	3.325 (1.257–8.790)
Anti-dsDNA IgG and anti-C1q	54%	79%	79%	54%	8.495 (3.436–21.002)
Anti-dsDNA IgA and anti-C1q	32%	87%	78%	47%	3.138 (1.053–9.356)
Anti-dsDNA IgG, IgA, and anti-C1q	32%	90%	82%	47%	4.038 (1.246–13.085)
Low C3 and/or C4	80%	71%	81%	69%	9.6 (3.566–25.844)

SLE: systemic lupus erythematosus; PPV: positive predictive value; NPV: negative predictive value; OR: odds ratio; CI: confidence interval.