Urinary protein and renal prognosis in idiopathic membranous nephropathy: a multicenter retrospective cohort study in Japan

Figures & data

Table 1. Clinical characteristics of patients with IMN.

	Total cohort
Number	171
Baseline characteristics
Age (years)	64 (57–70)
Male [n (%)]	118 (69.0)
Body mass index (kg/m^2)	23.1 (21.5–25.3)
Systolic blood pressure (mmHg)	130 (120–143)
Diastolic blood pressure (mmHg)	77 (70–85)
Serum creatinine (mg/dL)	0.80 (0.69–1.00)
eGFR (mL/min/1.73 m^2)	76 (60–91)
Serum albumin (g/dL)	2.5 (2.1–3.2)
Urinary protein (g/day)	4.3 (2.6–7.5)
Urinary protein ≥3.5 (g/day) [n (%)]	114 (66.7)
Total cholesterol (mg/dL)	285 (238–372)
Leg edema [n (%)]	131 (76.6)
Pleural effusion [n (%)]	33 (19.3)
ACE inhibitor or ARB therapy [n (%)]	156 (91.2)
Initial immunosuppressive therapy [n (%)]	101 (59.0)
Prednisolone [n (%)]	30 (17.5)
Prednisolone + cyclosporine [n (%)]	55 (32.1)
Interval until start of immunosuppressive   therapy (months)	0.7 (0–24)
Observation period (months)	37 (16–71)
Outcomes
Remission
Complete remission (CR) [n (%)]	103 (60.2)
Incomplete remission I (ICR I) [n (%)]	27 (15.8)
Incomplete remission II (ICR II) [n (%)]	20 (11.7)
No remission (NR) [n (%)]	21 (12.2)
Relapse [n (%)]	26 (15.2)
30% reduction in eGFR [n (%)]	37 (21.6)
Decline in eGFR (mL/min per 1.73m^2 per year)	2.5 (0–8.3)
ESRD [n (%)]	2 (1.1)
Death [n (%)]	11 (6.4)
Death due to infection [n (%)]	7 (4.1)
Hospitalization due to infection [n (%)]	13 (7.6)
Hospitalization due to cardiovascular disease [n (%)]	3 (1.8)
Malignancy [n (%)]	5 (2.9)

Median (interquartile range), Conversion factors for units: SCr in mg/dL to μmol/L, × 88.4; eGFR (mL/min/1.73 m²) = 194 × Scr^−1.094 × Age^−0.287 × 0.739 (if female), total cholesterol in mg/dL to mmol/L, × 0.02586.

IMN: idiopathic membranous nephropathy; eGFR: estimated glomerular filtration rate; ACE inhibitor/ARB: angiotensin-converting enzyme inhibitor/angiotensin receptor blocker; SCr: serum creatinine; ESRD: end-stage renal disease.

Figure 1. Cumulative probability of developing a 30% decrease in eGFR.

Figure 2. Cumulative probability of first complete remission.

Table 2. Predictors of a 30% decline in eGFR.

	Multivariate model
	HR (95%CI)	p value
Baseline data
Age (per year)	0.99 (0.94–1.03)	.501
Male (versus female)	1.49 (0.63–3.50)	.366
Systolic blood pressure (per 1 mmHg)	1.00 (0.98–1.01)	.645
Serum albumin (per 1.0 g/dL)	1.15 (0.59–2.23)	.681
Serum creatinine (per 1.0 mg/dL)	2.00 (0.45–8.84)	.361
ACE inhibitor or ARB therapy	0.44 (0.12–1.59)	.210
Urinary protein (per 1.0 g/day)	1.13 (0.99–1.29)	.060
Follow-up data
Urinary protein over time
No remission (NR; ≥3.5 g/day)	Reference
Incomplete remission II (ICR II; 1–3.5 g/day)	0.11 (0.02–0.59)	.010
Incomplete remission I (ICR I; 0.3–1g/day)	0.01 (0.001–0.19)	.002
Complete remission (CR; < 0.3g/day)	0.005 (0.0–0.08)	<.001
Immunosuppressive treatment
No immunosuppressive agents	Reference
Prednisolone	0.44 (0.08–2.53)	.355
Prednisolone + cyclosporine	2.45 (0.34–17.7)	.376

Data are the HR, 95%CI, and p values, adjusted for baseline data (age, sex, systolic blood pressure, serum creatinine level, serum albumin level, urinary protein level, and use of ACE inhibitors or ARBs within 6 months after kidney biopsy) from Cox regression models, and follow-up data (urinary protein and immunosuppressive treatment) from time-dependent Cox regression models.

‘No remission’ was used as the reference category.

IMN: idiopathic membranous nephropathy; ACE: angiotensin-converting enzyme; ARB: angiotensin receptor blocker; HR: hazard ratio; CI: confidence interval.

Figure 3. The course of eGFR during the follow-up period (comparison of the four proteinuria groups).