Background: The reported biopsy-proven glomerulonephritis incidence varies according to population characteristics, the unknown true glomerulonephritis incidence and biopsy rate. Reported glomerulonephritis incidence should be evaluated against the biopsy rate.
Methods: We report here the glomerulonephritis incidence in our University Hospital (UH) consecutive biopsy material. It is compared to those from surrounding central hospitals (CH), previous single-centre studies and European biopsy registries (EBR). Biopsy rate, when reported, has been considered.
Results: The annual biopsy rate/10(5), median (min-max), at the UHs was 25.4 (15.6-35.1). At the CHs it was 8.7 (5.1-12.6). In previous single-centre studies it has been 18.7-21.5. In the EBRs it has been between 1.0 and 6.9 when reported. The annual incidences (median, min-max) per 10(5) (1980-2000) at the UH were as follows: proliferative glomerulonephritis (9.5, 6.8-18.1), non-proliferative glomerulonephritis (6.7, 3.4-12.6), the four major glomerulonephritis groups MesGN (7.7, 4.4-15.9), ECGN/FPGN-complex (1.4, 0.5-3.2), MCGP/FSGS-complex (0.9, 0.2-2.7) and MGN (1.4, 0.5-2.4) these which findings were compatible with the single-centre studies and higher than those of the CHs and in the EBRs. Biopsy rate had a major impact on the annual glomerulonephritis incidences explaining 60% of the variation. The relative frequency of MesGN was the highest by all observers, followed by the ECGN/FPGN-complex, MGN and MCGP/FSGS-complex whose frequencies did not differ much. For every patient commencing renal replacement therapy (Finnish Renal Replacement Registry Data) due to glomerulonephritis there were about 11 subjects with biopsy-proven glomerulonephritis, a relationship compatible with previous reports.
Conclusions: The incidence of any glomerulonephritis of 17.6 per 10(5) population was comparable to those from the single-centre studies, but higher than in European biopsy registries, a fact largely explained by biopsy rates.