Introduction Membranous nephropathy is the commonest cause of nephrotic syndrome in non-diabetic Caucasian adults over the age of 40 years. Primary membranous nephropathy is limited to the kidneys. Clinical management aims to induce remission, either spontaneously with supportive care, or with immunosuppression. Here, we describe the natural history of this condition in a large tertiary centre in the UK. Methods 178 patients with primary membranous nephropathy were identified over 2 decades. We collected data on demographics, baseline laboratory values, treatment received and outcomes including progression to renal replacement therapy and death. Analysis was performed on the whole cohort and specific subgroups. Univariate and multivariate Cox regression was also performed. Results Median age was 58.3 years with 63.5% male. Median baseline creatinine was 90μmol/L and urine protein-creatinine ratio 664g/mol. Remission (partial or complete) was achieved in 134 (75.3%), either spontaneous in 60 (33.7%) or after treatment with immunosuppression in 74 (41.6%), and of these 57 (42.5%) relapsed. Progression to renal replacement therapy was seen in 10.1% (much lower than classically reported) with mortality in 29.8%. Amongst the whole cohort, those who went into remission had improved outcomes compared to those who did not go into remission (less progression to renal replacement therapy [4.5% vs 28%] and death [20.1% vs 67%]. Those classified as high-risk (based on parameters including eGFR, proteinuria, serum albumin, PLA2R antibody level, rate of renal function decline) also had worse outcomes than those at low-risk (mortality seen in 52.6% vs 10.8%, p<0.001). The median follow-up period was 59.5 months. Conclusion We provide a comprehensive epidemiologic analysis of primary membranous nephropathy at a large tertiary UK centre. Only 10.1% progressed to renal replacement therapy. For novelty, the KDIGO risk classification was linked to outcomes, highlighting the utility of this classification system for identifying patients most likely to progress.
BACKGROUND AND AIMS Membranous nephropathy (MN) commonly presents with nephrotic syndrome and carries significant risk of progression to end-stage kidney disease (ESKD) (33% without treatment, 10%–20% with). Patients may spontaneously remit (up to 40%), but are also at risk of relapse. A total of 80% of cases are primary (kidney-specific) and the majority of these are associated with antibodies to the M-type phospholipase A2 receptor (anti-PLA2R) or thrombospondin type 1 domain containing 7A antibodies (THS7DA). Treatment ranges from supportive care with renin–angiotensin system (RAS) blockade through to immunosuppression. Here we assessed the epidemiology of MN over 20 years at our centre (Salford Royal Hospital, UK) with particular reference to treatment administered and key clinical outcomes. METHOD A total of 238 patients with kidney biopsy-proven MN were identified from the local database between January 2000 and December 2020. Twenty-one were excluded (see Fig. 1) resulting in a total of 217 patients in whom demographic data, co-morbidities, remission and relapse rates, baseline laboratory values, treatment given, and outcomes were collected. Analyses compared effects of (i) immunosuppressed versus non-immunosuppressed, (ii) effect of modified Ponticelli versus other forms of immunosuppression and (iii) rates of remission. Univariate and multivariate cox regression determined factors that were associated with increased risk of renal replacement therapy (RRT) or death. RESULTS A total of 63.6% of the cohort were male, 88% Caucasian, 10.1% diabetic, 50.2% hypertensive and 15.2% had coexisting cardiovascular disease (Table 1). A total of 82.0% had primary MN. Median baseline eGFR was 72.7 mL/min/1.73 m2 and median baseline uPCR was 664 g/mol. A total of 157 patients (72.4%) went into remission (either spontaneous—75 (47.8%) or with treatment—85 (52.2%)), and of these 41.4% subsequently relapsed. A total of 89.4% received RAS blockade and 48.8% received immunosuppression. The median follow-up period was 56 months; 9.7% progressed to ESKD and 32.3% died. Patients who received immunosuppression had significantly more proteinuria than those who did not (765 g/mol versus 514 g/mol, P ≤ 0.001), were more likely to relapse (53.7% versus 28.0%, p ≤0.001) and were more likely to require RRT (15.1% versus 4.9%, P = .028). Those who received modified Ponticelli were less likely to relapse than those who received other forms of immunosuppression (34% versus 46%, P = .019), less likely to require RRT (3% versus 22%, P = .018) and less likely to die (11% versus 38%). Multivariate cox regression showed that pre-existing cardiovascular disease was a risk factor for death (HR 2.47, P < .001) and higher baseline eGFR and use of RAS blockade was associated with reduced risk of death (HR 0.98, P < .001 and HR 0.34, P = .012, respectively). CONCLUSION Despite advances in knowledge of underlying pathogenesis and increased treatment options, MN continues to pose a significant risk of progression to ESKD and death. This real-world study suggests that immunosuppression with modified Ponticelli is associated with lower rates of progressive CKD compared with MMF and calcineurin-inhibitor based therapy. Whilst many patients respond to treatment and can achieve remission, a significant proportion of these subsequently relapse. Identifying these patients early with judicial use of appropriate immunosuppression is key.
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