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 (∼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 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 progressive ageing of our nephrology patients, but also a change in the biopsy policy of local hospitals.