Table 1.

Characteristics of the included studies

Reference	Complement protein	Country	Adult/pediatric	Number	Method	Age, years	Male, %	eGFR, ml/mina	P-uria, g/daya
Yang et al.,22 2020	C4	China	Adult	642	IF	33.2	44	85.8 (60.9–110.3)	1.4 (0.7–2.9)
Bi et al.,23 2019	C4	China	Adult	1356	serum, turbidimetric	37	50	83.8 ± 34.2	2.2 ± 2.5
Pan et al.,24 2017	C3, C4	China	Adult	403	serum, turbidimetric	37.1	45	94.5 ± 30.9	1.2 ± 1.5
Nam et al.,25 2020	C3, C4d	Korea	Adult	380	IF:C3; IHC:C4d	36.1	43	85.2 ± 27.7	0.8 (0.3–1.7)
Segarra et al.,26 2018	C4d	Spain	Adult	190	IHC	29	65	100 (86–112)	1.8 (0.8–3.9)
Sato et al.,16 2019	C4d	Japan	Pediatric	25	IHC	11	36	125 (112–137)	1.4 (0.6–2.5)
Faria et al.,27 2020	C4d	Portugal	Adult	126	IHC	42	63	69.1 ± 40.5	1.8 (0.9–3.4)
Vellaisamy et al.,28 2021	C4d	India	Adult	76	IHC	35	38	64.9 ± 60.0	NA
Zhou et al.,29 2023	C4d	China	Pediatric	65	IF	NA	NA	NA	NA
Medrano et al.,30 2022	C4d	Spain	Adult	34	IHC	34	46	85 (72–101)	2.9 (0.9–3.7)
Wang et al.,11 2022	C4d	China	Adult	34	urine, ELISA	34	56	33.4 (16.2–61.7)	3.5 (1.7–5.1)
Itami et al.,31 2020	C3, C4, C4d, C1q, C5b9, MBL, MASP1/3, MASP2, properdin, factor B	Japan	Adult	132	IF	52	55	61.1 (9.7–162)	1.3 (0.04–7.8)
Yang et al.,32 2022	C4d	China	Adult	120	IHC	32	47	85.8 (60.3–110.7)	1.0 (0.8–3.5)
Baek et al.,33 2018	C4d	Korea	Pediatric	56	IHC	12.1	59	109.5 ± 32.4	0.5 (0.2–2.0)
Wen et al.,34 2019	Factor H, MBL, C5b9	Denmark	Adult	85	plasma, urine, ELISA	38	59	71.3 (43.3–111.6)	2.8 (1.4–4.9)
Guo et al.,35 2021	FHR5	China	Adult	56	IF; plasma, ELISA	40.1	38	96.4 (56.5–119.0)	1.4 (0.6–2.7)
Ouyang et al.,36 2019	MBL	China	Adult	606	SNP genotyping	36.9	51	73.3 (15.4–163.9)	1.3 (0.03–12.7)
Park et al.,37 2020	C3	Korea	Adult	453	IF	40.3	45	89.5 ± 28.5	0.7 (0.3–1.5)
Mizerska-Wasiak et al.,17 2021	C3	Poland	Pediatric	148	IF; plasma, turbidmetric	11.6	67	95.8 ± 33.5	1.4 (0.02–9.6)
Lang et al.,18 2021	C3; IgA/C3 ratio	China	Pediatric	41	IF:C3;IgA/C3: turbidmetric	9.3	63	118.8 ± 41.2	NA
Wu et al.,38 2021	C3	China	Pediatric	98	IF; plasma, turbidmetric	9.7	67	108.5 ± 37.1	2.7 (1.1–8.3)
Xie et al.,14 2023	C3	China	Adult	821	IF	34	53	91.8 (60.2–109.3)	1.5 (0.7–2.7)
Wu et al.,39 2021	C3	China	Adult	136	IF	36	49	96.9 (72.2–125.9)	1.0 (0.5–1.8)
Jullien et al.,15 2018	FHR1, FHR3, C3	France	Adult	639	PCR: FHR; IF:C3	40.1	75	74 (50–94)	0.7 (0.2–1.8)
Juan et al.,40 2022	C5a, Ba fragment	Taiwan	Adult	84	plasma, ELISA	44.7	46	54.9 ± 33.1	2.8 ± 3.1
Medjeral-Thomas et al.,41 2017	FHR1, FHR5	UK	Adult	294	plasma, ELISA	48.2	66	52.7 (28.7–82.7)	0.4 (0.1–1.1)
Guo et al.,13 2017	MBL	China	Adult	749	plasma, ELISA	34.7	48	83.8 ± 30.6	1.2 (0.6–2.5)
Zhu et al.,42 2018	FHR5	China	Adult	1126	plasma, ELISA	33	51	82.7 ± 30.6	1.3 (0.6–2.5)
Dumont et al.,19 2020	C5b9	Canada	Pediatric	67	IF	10.9	61	NA	NA
Yu et al.,43 2022	C5b9	Korea	Adult	33	urine, ELISA	40	52	79.7 ± 22.7	1.0 ± 1.0
Stefan et al.,44 2020	IgA/C3 ratio	Romania	Adult	95	serum, turbidmetric	41	70	39.4 (25.2–56.5)	1.7 (0.8–3.0)
Karahisar Sirali and Buberci,45 2022	IgA/C3 ratio	Turkey	Adult	43	serum, turbidmetric	43	40	77 ± 22.0	NA
Pan et al.,12 2018	C3/C4 ratio	China	Adult	712	serum, turbidimetric	37.3	43	90 ± 31	1.3 (0.7–2.6)
Coppo et al.,46 2019	CD46, CD55	VALIGA	Adult/Pediatric	157	PCR	36.8	67	70.9 (48.4–98.7)	1.1 (0.4–2.0)

ELISA, enzyme-linked immunosorbent assay; FHR, factor H-related protein; IF, immunofluorescence; IHC, immunohistochemistry; MASP, MBL associated serine protease; MBL, mannan binding lectin; PCR, polymerase chain reaction; SNP, single nucleotide polymorphism.

^aexpressed as mean with standard deviation (±) or median with interquartile range as reported in the original studies.