Is serum hemoglobin level an independent prognostic factor for IgA nephropathy?: a systematic review and meta-analysis of observational cohort studies

Figures & data

Figure 1. Flow diagram of study screening.

Table 1. Characteristics of included studies.

Author/year	Country	Study type	Follow-up^a (yrs)	Selective criteria for anemia (g/dL)	Patients (n)	Age^a (yrs)	Men n (%)	eGFR^a (mL/min/1.73 m^2)	Proteinuria^a (g/day)	Hemoglobin (g/dL)
Oh et al. [15] 2021	Korea	RCS	6.08	<13^b <12^c	4326	39.3	2141 (49.5)	75	N.R.	13
Zhai et al. [16] 2021	China	PCS	1.17	N.R.	394	35	212 (54)	N.R.	1.86	12.8
Jiang et al. [10] 2021	China	RCS	5.1	<12^b <11^c	1132	34.5	462 (40.81)	N.R.	2.0	N.R.
Yang et al. [18] 2020	China	RCS	3.6	<12^b <11^c	642	33.23	281 (43.77)	85.84	1.43	13.3
Zhu et al. [24] 2020	China	RCS	7	<12^b <11^c	1580	33.89	670 (42.41)	100.07	0.68	12.3
Lu et al. [23] 2020	China	RCS	2.08	<12^b <11^c	193	33.9	74 (38.34)	90.6	1.32	12.98
Xie et al. [14] 2018	China	RCS	4.69	N.R.	934	36.5	462 (49.5)	74.7	0.12	12.9
Caliskan et al. [17] 2016	Turkey	PCS	2.8	N.R.	111	35	69 (62.2)	56	1.8	12.5
Tanaka et al. [25] 2015	Japan	RCS	4.9	<13^b <12^c	694	36	330 (47.55)	80	1.24	13.5
Author/year	Events		UHR (URR) (95% Cl)	AHR (95% Cl)	Medication use, n (%)	Adjustments
	Anemia	Control
Oh et al. [15] 2021	N.R.	N.R.	2.78 [2.353, 3.285]^& 0.768 [0.736, 0.802]^#	1.675 [1.112, 2.522]^& 1.241 [0.871, 1.768]^b& 1.674 [1.097, 2.554]^c& 0.871 [0.773, 0.983]^#	N.R.	Age, sex, diabetes mellitus, serum albumin, systolic blood pressure, smoking history, uric acid and time stratified eGFR, log(urine protein creatinine ratio), total cholesterol, C- reactive protein.
Zhai et al. [16] 2021	N.R.	N.R.	0.96 [0.95, 0.98]^#	N.R.	N.R.	N.R.
Jiang et al. [10] 2021	N.R.	N.R.	N.R.	1.610 [0.962, 2.695]^&	RASI 1132 (100); Immunosuppression therapy if necessary.	Age, sex, total bilirubin,hypertension, ALT, AST, uric acid, triglycerides, total cholesterol,number of erythrocytes in urine at high magnification, lactate dehydrogenase,nephrotic syndrome,Glucocorticoids,CKD stages,Oxford classification (MEST) score, and crescents.
Yang et al. [18] 2020	17/79	64/563	0.99 [0.98, 1.00]^# 1.89 [1.17, 3.06]^&	N.R.	RASI 433(67.45); Immunosuppression therapy 378(58.88).	N.R.
Zhu et al. [24] 2020	80/389	103/1191	2.378 [1.818, 3.111]^&	1.64 [1.01, 2.68]^b& 1.68 [1.02, 2.76]^c&	RASI 1234 (78.1); Corticosteroids 1013 (64.36).	Age, 24-h proteinuria, eGFR, uric acid, mean arterial pressure, Oxford classification (MEST) score, crescents and treatments.
Lu et al. [23] 2020	4/36	6/157	0.968 [0.937, 1]^# 3.005 [0.846, 10.668]^&	N.R.	N.R.	N.R.
Xie et al. [14] 2018	N.R.	N.R.	0.77 [0.72, 0.82]^#	0.84 [0.77, 0.91]^#	RASI 591 (73); Corticosteroids 448 (55.1).	N.R.
Caliskan et al. [17] 2016	N.R.	N.R.	N.R.	0.782 [0.559, 0.973]^#	RASI 59 (53.2); Only prednisolone 25(22.5); Prednisolone + immunosuppressant 14 (12.6); Only Immunosuppressant 13 (11.7).	Age, sex, MAP, eGFR, Hgb, SCr, albumin, proteinuria, hematuria, Oxford classification, intensity and pattern of staining for C3, C1Q, IgA, IgG, IgM.
Tanaka et al. [25] 2015	32/334	43/508	1.132 [0.732, 1.751]^&	N.R.	RASI 341 (49.1); Steriod 235 (33.9).	N.R.

UHR: unadjusted HR; AHR: adjusted HR; ^&HR: calculated by comparing anemia with non-anemia IgAN patients for the incidence of kidney disease progression; ^#HR: calculated using serum Hb level as a continuous variable for the incidence of kidney disease progression in IgAN patients; N.R.: not reported; PCS: prospective cohort study; RCS: retrospective cohort study; ^aMedian or mean; ^bmale; ^cfemale; RASI: reninangiotensin system inhibitors.

Figure 2. Forest plot of correlation between serum Hb and kidney disease progression in IgAN (unadjusted HR).

Figure 3. Sensitivity analyses.

Figure 4. Forest plot of correlation between serum Hb and kidney disease progression in IgAN (adjusted HR).

Figure 5. Forest plot of correlation between serum Hb (as a dichotomous variable) and kidney disease progression in IgAN (unadjusted HR).

Figure 6. Forest plot of correlation between serum Hb (as a dichotomous variable) and kidney disease progression in IgAN (adjusted HR).

Figure 7. Forest plot of correlation between serum Hb and kidney disease progression in IgAN for different gender (adjusted HR).

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