Analysis of Erythrocyte C4d to Complement Receptor 1 Ratio: Use in Distinguishing between Infection and Flare-Up in Febrile Patients with Systemic Lupus Erythematosus

Table 4

Receiver operating characteristic (ROC) curve analysis of the utility of the C4d/CR1 ratio and serum CRP level in febrile SLE patients with infection.

Rules			Number(s)	Sensitivity (%)	Specificity (%)
A	C4d/CR1 > 1.2447	CRP > 4.67	1	4.55	100.0
		CRP < 4.67	3	13.64	12.5
	C4d/CR1 < 1.2447	CRP > 4.67	9	40.91	100.0
		CRP < 4.67	9	40.91	69.2
	Total		22
B	C4d/CR1 > 1.2447	CRP > 2.2	4	18.18	80.0
		CRP < 2.2	0	0	0
	C4d/CR1 < 1.2447	CRP > 2.2	13	50.09	86.7
		CRP < 2.2	5	22.73	71.4
	Total		22