Incidence of biopsy-proven glomerulonephritis

Nephrol Dial Transplant (2008) 23: 193–200 doi:10.1093/ndt/gfm564 Advance Access publication 25 August 2007 Original Article Incidence of biopsy-proven glomerulonephritis Ole Wirta1,2, Jukka Mustonen1,2, Heikki Helin3 and Amos Pasternack2 1 Department of Medicine, Tampere University Hospital, 2Medical School, University of Tampere, and 3Department of Pathology, Helsinki University Hospital Abstract 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 singlecentre studies and European biopsy registries (EBR). Biopsy rate, when reported, has been considered. Results. The annual biopsy rate/105, 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 105 (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 105 population was comparable to those from the single-centre studies, but higher than in Correspondence to: Ole Wirta, Harkontie 7, 33820 Tampere, Finland. Email: European biopsy registries, a fact largely explained by biopsy rates. Keywords: biopsy-proven glomerulonephritis; biopsy rate; glomerulonephritis incidence; IgA-glomerulonephritis; renal biopsy; renal pathology Introduction The incidence of glomerulonephritis varies according to the population genetic and demographic characteristics, environmental factors like climatology, socioeconomics, prevalence of infectious diseases and time period [1,2]. In addition, the incidence varies according to the detection level of urinary findings, the biopsy resources of the community and the biopsy policy which are reflected as the biopsy rate. A universally valid ‘epidemiology’ does not exist. One has to consider race, demography, population, era and biopsy rate. Kidney biopsy reports from single centres do exist, but reports considering biopsy rate are rare. In fact, few reports with control of the background population data, biopsy rate and biopsy policy over time exist. This is a report on the result from our university hospital compared to that of the Western region of Finland served by central hospitals (genetical and environmental equality), and especially to those studies concerned with European populations (socioeconomic equality) which have reported biopsy rate and biopsy indication. For details see Table 1. Subjects and methods The study was carried out from 1976 to 2000 in Western Finland. One university hospital (UH) and five central hospitals (CH1–5), all of them secondary referral centres, participated, for various lengths of time, the UH and one CH from 1976. The other CHs participated from 1980, 1982, 1990 and 1995, respectively. The common denominator for participating is that the kidney biopsy light microscopy (LM) specimens have been read by a single renal pathologist (H.H.) ß The Author [2007]. The online version of this article has been published under an open access model. Users are entitled to use, reproduce, disseminate, or display the open access version of this article for non-commercial purposes provided that: the original authorship is properly and fully attributed; the Journal and Oxford University Press are attributed as the original place of publication with the correct citation details given; if an article is subsequently reproduced or disseminated not in its entirety but only in part or as a derivative work this must be clearly indicated. For commercial re-use, please contact Downloaded from https://academic.oup.com/ndt/article-abstract/23/1/193/1924779 by guest on 08 June 2018 194 O. Wirta et al. Table 1. Summary of European studies, including one from Australia, concerned with biopsy-proven glomerulonephritis Centres Country Period Population Observations Biopsy rate per 105 Glomerulonephritis incidence per 105 IgAGN incidence Reference National Registry Denmark 1985–1997 5.2  106 2380 4.0 calculated 1.1 [13] National Registry Italy 1987–1993 13835 NG 0.8 [14,15] Torino Moldova/Banat Twenty-eight centres Brittany National Registry Italy Romania Czech Republic France Spain 1970–1994 1995–2004 1994–2000 Virtually all Centres
2  106 6.2  106 3.9 observed 7.9 estimated 3.4 1926 635 4004 NG 1.1 4.4-6.9 4.7 3.9 4.6 1.5 1.0 1.1 [16] [17] [18] 1976–1990 1994–1999 942 7016 18.7–20.1–16.3 4.8 9.3–8.8–6.7 >3.5 2.5–3.1 0.8 [19,20] [21] Victoria Australia 1995–1997 2030 21.5 12.3 10.5 [22] 391 265 Ninety-three centres 4.5  106 The definition of glomerulonephritis varies between studies in terms of ‘any-, primary-, secondary-’. For details see appropriate reference. NG, not given. and all of the immunofluorescence (IF) specimens by J.M. or occasionally by H.H. The Western region of Finland is an area with a high standard of living, a population nearly totally of Caucasian race, an extensive primary health care system and low incidences of chronic infectious diseases like impetigo, hepatitis C and B, and HIV-related conditions. Nephropathia epidemica caused by Puumala hantavirus is endemic (seroprevalence
5%). It causes acute reversible renal failure with albuminuria and haematuria [3]. Routine urinary screening is carried out in maternity and child health welfare clinics, schools, work-places and some military service health systems (thus, nearly all young males are screened). The recruitment threshold for a kidney biopsy is low. Population data are electronically available from 1980 onwards. The incidences were calculated from 1980 to 2000 at the UH. The population in the area has been stable in terms of numbers, UH median 423 6 (...truncated)