Antibodies against C1q Are a Valuable Serological Marker for Identification of Systemic Lupus Erythematosus Patients with Active Lupus Nephritis

Table 6

Significant differences in concentration, sensitivity, specificity, and odds ratio (OR) based on disease activity in SLE patients ().

	Sensitivity (%)	Specificity (%)	PPV (%)	NPV (%)	OR (95% CI)
Anti-C1q Ab	40/51 (78.4)	34/44 (77.3)	40/50 (80.0)	34/45 (75.6)	12.364 (4.683–32.640)
Anti-dsDNA Abs	50/51 (98.0)	16/44 (36.4)	50/78 (64.1)	16/17 (94.1)	28.571 (3.596–227.008)
Levels of C3 and C4	46/51 (90.2)	29/44 (65.9)	46/61 (75.4)	29/34 (85.3)	17.787 (5.840–54.172)
Anti-dsDNA Ab, levels of C3 and C4	45/51 (88.2)	24/44 (54.5)	45/65 (69.2)	24/30 (80.0)	17.885 (6.134–52.143)
Abs to C1q and dsDNA	39/51 (76.5)	40/44 (90.9)	39/43 (90.7)	40/52 (76.9)	14.625 (5.365–39.846)
Anti-C1q Ab, levels of C3 and C4	40/51 (78.4)	42/44 (95.5)	40/42 (95.2)	42/53 (79.2)	23.030 (7.749–68.451)
Abs to C1q and dsDNA, levels of C3 and C4	37/51 (72.5)	41/44 (93.2)	37/40 (92.5)	41/55 (74.5)	26.429 (7.987–87.549)

The sensitivity, specificity, and predictive values were calculated using formula described in a previous report [27]. PPV: positive predictive value; NPV: negative predictive value.