Incidence of primary glomerulonephritis in a large North-Eastern Italian area: a 13-year renal biopsy study

Background. The reported incidence of biopsy-proven primary glomerulonephritis (PGN) varies according to geographical, temporal and environmental factors. Consequently, the development of national/regional registers may help clinicians and researchers to improve knowledge about this important clinical condition. Methods. To better define the epidemiology of PGN in our North-Eastern Italian area (similar to 5 million inhabitants), we evaluated the kidney biopsy records of 2680 adult patients with PGN diagnosis reported from 1998 to 2010 in the 'Triveneto' Register of Renal Biopsies. Results. Statistical analysis showed that the mean age of patients undergoing renal biopsy was gradually increased from 1998 to 2010 (R-2 = 0.82, P < 0.01) with a growing percentage of those aged over 65 years (R-2 = 0.72, P < 0.01). According to the clinical presentation of our PGN patients, we found a significant increase in biopsies performed for acute renal failure (P < 0.01) and a progressive ageing of our nephrology patients, but also a change in the biopsy policy of local hospitals.decrement of those for macroscopic haematuria (P < 0.01) and nephritic syndrome (P = 0.04). Moreover, although there has been an unchanged total annual rate of biopsy-proven PGN (P = 0.47), there has been a significant enhancement in the incidence of minimal change disease (MCD, P = 0.04) and extracapillary proliferative glomerulonephritis (ExGN, P = 0.03) over time primarily due to a progressive increase in the mean age of patients affected by both renal diseases. Immunoglobulin A (IgA) nephropathy was the most common glomerulonephritis. Conclusions. Therefore, even if the number of PGN did not diminish during the 13-year study period, we reported considerable changes in the demographical and clinical characteristics of our biopsied patients (older and with acute kidney injury). Additionally, we found a change in the bioptic pattern of our patients over time with a progressive rise of some histological features such as MCD and ExGN. This may reflect not only the