Clinicopathological characteristics and outcomes of adult idiopathic membranous nephropathy

Objective  To explore the clinicopathological features and outcomes of adult idiopathic membranous nephropathy (IMN) and examine the influencing factors of renal outcomes.

Methods From January 2012 to June 2023, the clinicopathological data were retrospectively reviewed for 646 patients diagnosed initially as IMN by renal biopsy. Cox proportional risk model and Kaplan-Meier survival curve were utilized for conducting survival analysis for 486 patients with a follow-up duration of at least 6 months until December 2023.

Results  Among 646 IMN patients, male-to-female ratio was 1.33∶1 and 521 patients (80.7%) were aged ≥40 year. The predominant pathological stage was II (73.1%). There were glomerular global sclerosis (n=387, 59.9%), segmental sclerosis (n=99, 15.3%), renal tubulointerstitial lesions (n=554, 85.8%) and renal small vessel lesions (n=540, 83.6%). Single-factor Cox regression analysis revealed that advanced age, serum creatinine, uric acid, hypertension, triglyceride, 24 h urine protein quantification, glomerular global sclerosis, segmental sclerosis and tubulointerstitial lesions were the risk factors for poor renal outcomes whereas eGFR, plasma albumin and hemoglobin were the protective factors. After multifactorial corrections, only age was an independent risk factor for poor renal outcomes (HR=1.042, 95%CI: 1.015-1.069, P=0.002). Kaplan-Meier survival curve analysis revealed that renal survival rates were lower in moderate/severe glomerular global sclerosis group than those in non-glomerular global sclerosis and mild glomerular global sclerosis groups (P<0.05). Renal survival rate was significantly lower in segmental sclerosis group than non-sclerosis groups (P<0.001). Group with moderate-to-severe tubulointerstitial lesions had significantly lower renal survival rates than group without tubulointerstitial lesions (P=0.001) and group with mild tubulointerstitial lesions (P=0.001).

Conclusions  IMN is prevalent in middle-aged and elderly people. Moderate/severe glomerular global sclerosis, segmental sclerosis and moderate-to-severe tubulointerstitial lesions collectively contribute to a lower renal survival rate in IMN patients. However, only age may be employed as an independent predictor of renal outcomes.