Abstract
BackgroundGlomerular IgM deposition is commonly shown in idiopathic membranous nephropathy (IMN), but the clinicopathological features and outcomes of IMN with IgM deposition are unclear.MethodsThis single-center prospective cohort study enrolled 210 patients with biopsy-proven IMN from January 2016 to December 2018. Clinicopathological features, treatment responses, and kidney outcomes were compared between patients with and without IgM deposition.Results76 (36.2%) patients shown glomerular IgM deposition. Patients with IgM deposition were younger (45±13.296 vs. 50.59±13.65 years, P=0.006), had a higher estimated glomerular filtration rate (eGFR) (100.03 [81.31–111.37] vs. 92.67 [74.71–106.63] mL/min/1.73 m2, P=0.041), and had a lower proportion of nephrotic syndrome (60.5% vs. 75.4%, P=0.024) at the time of kidney biopsy. Patients with IgM deposition had a significantly higher proportion of focal segmental glomerular sclerosis (FSGS) lesions (27.6% vs. 13.4%, P=0.011) and C1q deposition (72.4% vs. 57.5%, P=0.032). Although the treatments and initial treatment responses were comparable, patients with glomerular IgM deposition had a significantly greater proportion of eGFR decline of ≥5 mL/min/1.73 m2 per year (log-rank test, P<0.001) and eGFR decrease of ≥10% from baseline (log-rank test, P=0.003). Cox regression analysis showed that IgM deposition was an independent risk factor of eGFR decline of ≥5 mL/min/1.73 m2 per year (HR, 2.442; 95% CI, 1.550–3.848, P<0.001) and eGFR decline by ≥10% from baseline (HR, 2.629; 95% CI, 1.578–4.385, P<0.001) during follow-up.ConclusionsGlomerular IgM deposition is associated with younger age, more severe FSGS lesions and C1q deposition, and worse renal outcomes in IMN.