The Changing Spectrum Of Biopsy-Proven Primary Glomerular Diseases

Chronic kidney disease(CKD) has become a worldwide notable public health problem. It is reported that the incidence of CKD is as high as 200-400 cases per million per year. The onset and development of CKD are slow, and symptoms are obscure. For Most patients, CKD appears asymptomatic, but it suddenly comes to the end-stage. So CKD is known as the "silent killer" to the medical staff. The patients who developed end stage renal disease require renal replacement therapy, such as renal transplantation, hematodialysis or peritoneal dialysis. To patients and their families, social these treatments cause great mental and economic pressure. According to the China National Survey of CKD, done by peking university first hospital from January,2007, to October,2010, In Chinese adults, the prevalence of CKD was 10.8%. A similar rate was found in developed countries, such as the US (13.1%) by the end of the 2004 data. CKD has received increasing attention as a worldwide health problem due to its increasing incidence and prevalence, poor outcome and high associated expenses. Primary glomerular diseases is the leading cause of end-stage renal disease in China. Some recent studies have shown that primary glomerular diseases is still the most common renal disease among patients receiving renal biopsy in China. The prevalence of primary glomerular diseases in renal biopsy specimens has been reported to range from 63.3% to 71.1%. A limited number of single center studies have shown that the renal histopathological spectrum of primary glomerular diseases has continuously changed in recent years. One of these changes is the frequency of membranous nephropathy (MN,15.7%-29.2%), which has increased significantly. IgA nephropathy is still the most common primary glomerular diseases in China and other countries. In Europe, Oceania, and Asia, IgA nephropathy occurs with the greatest frequency and accounts for 36.8-54.2% of primary glomerular diseases. In addition, the proportion of IgA nephropathy tended to increase year after year, but some studies have not found the same trend in the same period. To the best of our knowledge, the most recent pathological data date back to 2012. More than two years have passed and there may be new changes. Furthermore the present study are smaller single-center study. In order to discover the latest changing spectrum of biopsy-proven primary glomerular diseases, We collected Kidney histopathology results of the last five years to analyze from two large renal pathological examination center of Shandong province, a total of 37 hospitals.Aim:primary glomerular diseases remain the most common renal disease in China. A limited number of single center studies show that the frequency of MN has increased; however, IgA nephropathy is still the most common primary glomerular diseases. To the best of our knowledge, there has been no multi-centre study in China that has explored the changes in primary glomerular diseases spectrum. To further investigate the latest changes in renal histopathological spectrum, we performed the cross-sectional study.Method:From June 2010 to May 2015,5935 patients from 37 hospitals in Shandong Province were involved in this retrospective study. The records of 6017 patients with renal biopsy performed in 37 hospitals from Shandong province were retrospectively analyzed from June 1,2010 to May 31,2015. Incomplete records (n=21) and inadequate biopsies (<10 glomeruli in the specimen using light microscopy when there were no typical findings by immunofluorescence microscopy or electron microscopy or absence of a glomerulus by immunofluorescence microscopy, n=44) and repeat biopsies (n=17) were excluded. Thus,5935 qualified cases were enrolled in this retrospective study. The study was divided into 5 periods according to 1-year intervals. The study was divided into 5 periods according to 1-year intervals. The patients were divided into 4 age groups (pediatric patients.≤18 years; young patients,19-44 years; middle-aged patients,45-59 years and elder patients,≥60 years).Result:Among the 5935 qualified renal biopsies,4855 (81.8%) patients were diagnosed as having primary glomerular diseases. Among the 4855 primary glomerular diseases patients,2610 (53.8%) were male,2245 and (46.2%) were female. The mean age was 39.78±15.43 years (range 1-88 years) at the time of the renal biopsy. In the 5 periods, the mean age was 39.3±14.4 years,38.1±13.9 years,39.0±15.8 years,40.2±16.1 years and 41.6±15.9 years, respectively.When stratified by age, the data showed that primary glomerular diseases had the highest incidence in young patients [(54.0%)], followed by middle-aged patients [(27.1%)], elder patients [(11.4%)] and pediatric patients [(7.2%)].Spectrum of primary glomerular diseases during the entire period and at different periodsAccording to table 1, in a total of 4855 primary glomerular diseases patients, the leading cause was membranous nephropathy [MN,2103 (43.3%)], followed by IgA nephropathy [IgAN,1655 (34.1%)], minimal change disease [MCD,488 (10.3%)], focal segmental glomerulosclerosis [FSGS,332 (6.8%)], membranoproliferative glomerulonephritis [MPGN,64(1.3%)], sclerosing glomerulonephritis [SclGN, 49 (1.0%)], crescentic glomerulonephritis [CreGN,45 (0.9%)], endocapillary proliferative glomerulonephritis [EnPGN,37 (0.8%)] and mesangial proliferative glomerulonephritis [MsPGN,27(0.6%)].As indicated in figure 1, the proportion of MN has significantly increased in the last 5 years, accounting for 30.7%,34.5%,39.4%,50.7% and 53.5% in periods 1,2, 3,4 and 5, respectively. Furthermore, MN instead of IgAN has become the leading cause of the primary glomerular diseases from period 3. IgAN was the main cause of primary glomerular diseases in period 1 and period 2. However, its proportion decreased significantly from 41.8% in period 2 to 25.2% in period 5 (p<0.001). The proportion of FSGS tended to decrease from 11.1% in period 2 to 4.1% in period 5 (p<0.001). The proportion of MCD was the highest in period 1 (17.8%), but it decreased to 9.6% in period 5.Spectrum of primary glomerular diseases according to age stratificationWhen stratified by age, there were 349 (7.2%),2623 (54.0%),1317 (27.1%) and 555 (11.4%) patients with renal biopsy in the≤18,19-44,45-59 and≥60 year groups, respectively.According to figure 2, with increasing age, the proportion of MN was significantly increased, accounting for 29.8% in pediatric patients,38.3% in young patients,48.6% in middle-age patients and 63.2% in elder patients. In contrast, the proportion of MCD demonstrated the opposite results. IgAN exhibited the highest incidence (38.5%) in young patients, and with increasing age, its incidence decreased to 18.9% in elder patients. As indicated in figure 3, the prevalence of MN tended to increase for every age group. However, according to figure 4, the proportion of IgAN demonstrated the opposite results. In addition, IgAN showed the highest incidence in young patients.In a total of 349 pediatric patients (≤18 years) with primary glomerular diseases the leading cause was IgAN (121,34.7%), followed by MN (104,29.8%), MCD (71, 20.3%), EnPGN (16,4.6%), FSGS (15,4.3%), MPGN (6,1.7%), SclGN (5,1.4%), CreGN (2,0.6%) and MsPGN (1,0.3%).In young patients, IgAN is the most common primary glomerular diseases, accounting for 38.5%, followed by MN (38.3%), MCD (10.6%), FSGS (8.0%), SclGN (1.1%), MPGN (0.9%), CreGN (0.7%), MsPGN (0.6%) and EnPGN (0.5%). In middle-age and elder patients, the leading cause was MN (48.6% vs.63.2%), followed by IgAN (31.5% vs.18.9%), MCD (8.0% vs.5.8%), FSGS (6.4% vs.4.0%) and MPGN (1.6% vs.2.5%).Conclusion:In conclusion, primary glomerular diseases is the most common renal disease among patients receiving renal biopsy in our study. The spectrum of primary glomerular diseases is changing in China. The prevalence of MN in primary glomerular diseases increased year after year. However, IgAN demonstrated opposite results. Consequently, MN instead of IgAN has become the first leading pathological type of primary glomerular diseases, which accounts for the main change in the spectrum of primary glomerular diseases in the past 5 years.