Assessment of the long term cardiovascular and renal outcomes in primary glomerulonephrites

Primary glomerulonephritis is a disease that is not due to any underlying diseases and affects the glomeruli. Membranous nephropathy, focal segmental glomerulosclerosis and IgA nephropathy are the frequent types of primary glomerulonephritides in the adulthood. Glomerulonephritides may progress into end-stage renal disease despite appropriate treatment. Both the manifestations of the glomerulonephritides and medications for treatment might yield cardiovascular events such as venous thromboembolism, coronary artery disease and stroke. The purpose of this study is to compare three different types of primary glomerulonephritides in terms of all-cause mortality, kidney-related and cardiovascular outcomes. All patients who underwent kidney biopsy between 01.01.2000 and 01.06.2022 in Hacettepe University Hospitals were screened and cases fulfilling the inclusion criteria were enrolled. Data regarding baseline demographics, laboratory and kidney pathology reports and outcomes were obtained. The primary end-point was defined as all-cause mortality. Kidney related and cardiovascular outcomes were determined as secondary end-points. A total of 471 patients consisting 266 (56.5%) male and 205 (43.5%) female, were included in the study. Median age of the study population was 39 (18-81) years. Membranous nephropathy was present in 36.5% (n=172), focal segmental glomerulosclerosis was present in 25.9% (n=122) and IgA nephropathy was present in 37.6% (n=177) of the cases. Age (p<0.001), frequency of diabetes (p=0.004) and smoking history (p=0.020) were significantly higher in patients with membranous nephropathy than both FSGS and IgA nephropathy. Albumin level was lower (p<0.001), while total cholesterol (p<0.001), LDL cholesterol (p<0.001) and proteinuria levels (p<0.001) were higher in patients with membranous nephropathy than other two groups and in patients with FSGS than IgA nephropathy. Median duration of follow-up was 120.2 (1.7-273.3) months. All-cause mortality rate was significantly higher in patients with membranous nephropathy than other two groups (p=0.005); however the type of glomerulonephritides not found to be related to all-cause mortality (HR:1.07; %95 CI:0.65-1.77; p=0.770). Age (HR:1.079; %95 CI:1,05-1,10; p<0,001), creatinine (HR:1.35; %95 CI:1.10-1.66; p=0,003) and albumin (HR:0.60; %95 CI:0.38-0.95; p=0.030) levels were found to be associated with all-cause mortality in patients with primary glomerulonephritides. The rates of ischemic stroke, atrial fibrillation and steroid induced diabetes were similar between all of the glomerulonephritides subgroups. Acute coronary syndrome (p=0.015), coronary revascularization (p=0.021) and venous thromboembolic events were more frequent in patients with membranous nephropathy than cases with IgA nephropathy. There was no difference in terms of cardiovascular outcomes between the patients with FSGS and IgA nephropathy. Although the remission rate was significantly higher in patients with membranous nephropathy than other two groups (p<0.001); there was not a distinct difference in relapse rates. Progression to end-stage renal disease was prominently lower in patients with membranous nephropathy than other groups (p=0.003) and loss of glomerular filtration rate per year was significantly higher in cases with FSGS compared to other groups (p=0.021). In conclusion; all-cause mortality risk was higher in patients with membranous nephropathy because of higher age at diagnosis and accompanying higher burden of comorbidities including diabetes and dyslipidemia. FSGS had a worse prognosis in terms of kidney related outcomes compared to other glomerlonephritides due to higher loss of glomerular filtration rate per year and increased rates of progression to end-stage renal disease.