Role of serum anti-C1q antibodies as a biomarker for nephritis activity in pediatric and adolescent Egyptian female patients with SLE

Figures & data

Table 1. Comparison between mean age of patients in all groups.

Variables	Group 1, n = 40	Group 2, n = 40	Group 3, n = 40	p
Age (mean ± SD) years	16.7 ± 3	16.1 ± 2	15.9 ± 3	> 0.05

Table 2. Comparison between the studied groups as regard laboratory data.

Variables	Group 1, n = 40 (mean ± SD)	Group 2, n = 40 (mean ± SD)	Group 3, n = 40 (mean ± SD)	F	P	Post hoc (LSD)^‡
HB (11 – 15) g/dl	9.2 ± 3	9.9 ± 2	10.8 ± 2	0.6	> 0.05
TLC (4 – 11) (10^3 × mm^3)	8.8 ± 2	7.4 + 2	6.8 ± 1.7	0.9	> 0.05
Platelets (150 – 450) (10^3 × mm^3)	191 ± 58	158 ± 60	189 ± 50	1.1	> 0.05
ESR (3 – 14) mm/h	88 ± 11	51 ± 10	12 ± 3	0.8	< 0.001	1 versus 2 and 3
Glucose random < 200 mg/dl	120 ± 38	112 ± 20	109 ± 11	1.6	> 0.05
Urea (8 – 21) mg/dl	52 ± 25	29.6 ± 20	20 ± 8	1.9	> 0.05
Creatinine (0.3 – 1.2) mg/dl	1.5 ± 0.2	1.2 ± 0.3	1.1 ± 0.3	1.6	> 0.05
24 h Protein < 0.3 g	1.9 ± 0.7	0.22 ± 0.4	0.11 ± 0.12	1.3	< 0.001
C3 (90 – 140) U/l	53 + 20	83 + 16	85 ± 19	34	< 0.001	1 versus 2 and 3
C4 (10 – 40) U/l	14.7 + 4	35.7 + 10	39.4 ± 8	40	< 0.001	1 versus 2 and 3
Anti C1q U/l, Median (IQR)	27.5 (14-83)	9 (2.5-30)	7 (2-13)	13*	< 0.001	1 versus 2 and 3
CRP(< 0.5 mg/l)	13(32.5%)	11(27.5%)	-	-	> 0.05

*Kruskal–Wallis test.

^‡Least significant difference.

IQR: Inter quartile range (0.25 – 75th percentile).

Figure 1. Comparison between anti-C1q antibodies in the three groups.

Table 3. Correlation between anti-C1q antibodies versus all variables among cases (group 1).

Variables	Anti-C1q
	r	p
Age	0.19	> 0.05
HB	0.09	> 0.05
TLC	0.11	> 0.05
Platelets	0.14	> 0.05
ESR	0.026	> 0.05
Glucose	-0.02	> 0.05
Urea	0.1	> 0.05
Creatinine	0.24	> 0.05
24 h urine proteins	0.33	< 0.03
C3	-0.33	< 0.04
C4	-0.32	< 0.04
Renal SLEDAI	0.65	< 0.001
Activity index	0.71	< 0.001
Chronicity index	0.15	< 0.33

Figure 2. Correlation between anti-C1q antibodies versus C3, C4, Proteinuria, and renal SLEDAI and Activity index in cases (group 1).

Table 4. Correlation between anti-C1q antibodies versus all variables among group without active lupus nephritis (group 2).

Variables	Anti-C1q
	r	p
Age	0.08	> 0.05
HB	0.02	> 0.05
TLC	0.16	> 0.05
Platelets	0.15	> 0.05
ESR	0.16	> 0.05
Glucose	-0.17	> 0.05
Urea	0.10	> 0.05
Cr	0.20	> 0.05
24 h Proteins	-0.30	> 0.05
C3	-0.42	< 0.001HS
C4	0.07	> 0.05

Figure 3. Correlation between anti-C1q antibodies and C3 among group without active lupus nephritis (group 2).

Table 5. Correlation between anti-C1q antibodies versus all variables among controls (group 3).

Variables	Anti-C1q
	r	p
HB	-0.09	> 0.05
TLC	0.02	> 0.05
Platelets	0.08	> 0.05
ESR	0.18	> 0.05
Glucose	0.17	> 0.05
Urea	-0.03	> 0.05
Cr	0.02	> 0.05
24 h Protein	0.16	> 0.05
C3	0.11	> 0.05
C4	-0.04	> 0.05

Table 6. Validity of anti-C1q antibodies in prediction of lupus nephritis in group 1 patients.

Variables
Area under the curve	0.81
Best cut off	> 12
Sensitivity	97.5%
Specificity	65%
PPV	74%
NPV	96%
Standard error	0.052
Significance level (p)	< 0.0001

Figure 4. ROC curve for anti-C1q in lupus nephritis.

Table 7. Validity of C3 in prediction of lupus nephritis in group 1 patients.

Variables
Area under the curve	0.87
Best cut off	≤ 61
Sensitivity	67.5%
Specificity	95%
PPV	93%
NPV	75%
Standard error	0.041
Significance level (p)	< 0.0001

Figure 5. ROC curve for C3 in lupus nephritis.

Table 8. Validity of C4 in prediction of lupus nephritis in group 1 patients.

Variables
Area under the curve	0.96
Best cut off	≤ 22
Sensitivity	85%
Specificity	100%
PPV	100%
NPV	87%
Standard error	0.021
Significance level (p)	< 0.0001

Figure 6. ROC curve for C4 in lupus nephritis.