1 Department of Epidemiology and Preventive Medicine, Monash University, 2 Department of Pathology, Monash Medical Centre, 3 Department of Pathology, Alfred Hospital, 4 Department of Pathology, Royal Melbourne Hospital, 5 Department of Pathology, St Vincent's Hospital, 6 Department of Nephrology, Royal Children's Hospital, 7 Department of Medicine, Epworth Hospital, 8 Department of Pathology, Austin and Repatriation Medical Centre 9 Department of Nephrology, Monash Medical Centre, Australia
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Abstract |
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Methods. A retrospective review of the pathology reports of all native renal biopsies performed in the Australian state of Victoria in 1995 and 1997 was undertaken. Trends in the average annual age- and sex-specific incidence rates for biopsy-proven glomerulonephritis were calculated. Comparisons were made with the incidence of end-stage renal disease due to glomerulonephritis confirmed on renal biopsy.
Results. The most common glomerulonephritides in adults are IgA disease, focal glomerulosclerosis, lupus nephritis and vasculitis, and in children are lupus nephritis, focal glomerulosclerosis, IgA disease and minimal change disease. A male predominance is seen for all glomerulonephritides, except lupus nephritis, in both adults and children. An increase in incidence of disease with age, particularly in males, is seen for vasculitis and focal glomerulosclerosis. The most common glomerulonephritides on renal biopsy are reflected in the most common causes of end-stage renal disease due to glomerulonephritis.
Conclusions. This review has provided population-based descriptive epidemiological data on clinically significant glomerulonephritis. This data provides important clues for further studies relating to the identification of risk factors for the various types of glomerulonephritis.
Keywords: epidemiology; glomerulonephritis; renal biopsy
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Introduction |
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Subjects and methods |
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A total of 2030 renal biopsies were performed. The age or sex of patients was not known for 13 (0.6%) of the biopsies. A total of 12 (0.6%) biopsies included no renal tissue and 18 (0.9%) biopsies were reported as normal, all from adults. Reports of the remaining 1987 biopsies104 from children (<15 years of age) and 1883 from adults (15 years of age)were reviewed and categorized by histological diagnosis. Of these, a total of 1147 renal biopsies had a histological diagnosis of glomerulonephritis and were included in this analysis. Categories included anti-glomerular basement membrane disease, cryoglobulinaemia, focal glomerulosclerosis, IgA disease, lupus nephritis, membranoproliferative glomerulonephritis, membranous nephropathy, minimal change disease, post-infectious glomerulonephritis, thrombotic microangiopathy and vasculitis.
A comparison of types of biopsy-proven glomerulonephritis in the general population and in patients with end-stage renal disease was made using data from the Australia and New Zealand Dialysis and Transplant Registry for 1995 and 1997 [1,2]. Of all patients with end-stage renal disease attributed to glomerulonephritis, a biopsy diagnosis was available for 77% of patients in 1995 and 74% of patients in 1997. The incidence of end-stage renal disease due to glomerulonephritis confirmed on biopsy was calculated for the total population of Australia and compared with the incidence of biopsy-proven glomerulonephritis in Victoria for the same time periods.
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Results |
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The rate of renal biopsy was significantly more in females compared with males in the 2534 year age group (odds ratio (OR): 1.53; 95% confidence interval (CI): 1.21, 1.94). It was significantly more in males compared with females in the 5564 year age group (OR: 1.50; 95% CI: 1.19, 1.88), the 6574 year age group (OR: 2.03; 95% CI: 1.62, 2.55), and the 75+ year age group (OR: 2.75; 95% CI: 1.91, 3.95).
Incidence of biopsy-proven glomerulonephritis in children (see Tables 1 and Table 2
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The most common glomerulonephritis in children under the age of 5 years was focal glomerulosclerosis (0.5 per 100 000 per year), followed by minimal change disease and IgA disease. In children of 514 years of age, the most common diagnosis was lupus nephritis (1.7 per 100 000 per year), followed by IgA disease and focal glomerulosclerosis.
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Incidence of biopsy-proven glomerulonephritis in adults (see Table 1 and Table 2
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In adults, the most common glomerulonephritis was IgA disease (10.5 per 100 000), followed by focal glomerulosclerosis and vasculitis. IgA disease was the most common diagnosis in patients up to 65 years of age (1524 years: 3.9 per 100 000 per year; 2534 years: 5.7 per 100 000 per year; 3544 years: 5.0 per 100 000 per year; 4554 years: 6.1 per 100 000 per year; and 5564 years: 6.8 per 100 000 per year). The most common diagnosis was vasculitis in the 6574 year age group (5.8 per 100 000 per year) and in those 75 years and over (4.0 per 100 000 per year).
In adults, the following diagnoses were significantly more common in males than females: anti-glomerular basement membrane disease (OR: 8.35; 95% CI: 1.04, 66.77), post-infective glomerulonephritis (OR: 3.65; 95% CI: 1.20, 11.10), membranous glomerulonephritis (OR: 2.23; 95% CI: 1.51, 3.29), IgA disease (OR: 1.95; 95% CI: 1.57, 2.40), vasculitis (OR: 1.69; 95% CI: 1.20, 2.39) and focal glomerulosclerosis (OR: 1.60; 95% CI: 1.19, 2.16). Lupus nephritis was significantly more common in females compared with males (OR: 2.75; 95% CI: 1.89, 3.84).
Incidence of end-stage renal disease (see Table 3 )
For the most common types of glomerulonephritis, i.e. IgA disease and focal glomerulosclerosis, the incidence of biopsy-proven disease was about six times that of end-stage renal disease (OR: 6.5 (95% CI: 5.5, 7.6) and OR: 6.0 (95% CI: 4.8, 7.5), respectively). The incidence of biopsy-proven lupus nephritis and membranous nephropathy was 16 times greater than their incidence of end-stage renal disease, while vasculitis was about eight times greater (OR: 16.0 (95% CI: 11.3, 22.5), OR: 13.5 (95% CI: 9.3, 19.5) and OR: 8.5 (95% CI: 6.3, 11.3), respectively). For the more uncommon causes of biopsy-proven glomerulonephritis, a marked disparity was seen for thrombotic microangiopathy, less so with anti-glomerular basement membrane disease, and minimal disparity for membranoproliferative glomerulonephritis (OR: 116.4 (95% CI: 16.0, 854.1), OR: 9.0 (95% CI: 3.0, 27.6) and OR: 3.2 (95% CI: 1.9, 5.5), respectively).
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Other renal biopsy diagnoses
The only other significant category of renal disease diagnosed on renal biopsy in children was interstitial nephritis, with an incidence of 0.3 per 100 000 per year. In adults, other renal diseases included thin basement membrane disease (2.5 per 100 000 per year), diabetic nephropathy (1.7 per 100 000 per year), nephrosclerosis (1.7 per 100 000 per year), interstitial nephritis (1.4 per 100 000 per year), amyloidosis (0.3 per 100 000 per year) and cholesterol emboli (0.2 per 100 000 per year).
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Discussion |
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The average annual rate of renal biopsy found in this review was considerably greater than that reported in other studies. The observed biopsy rate for all ages was seven times as frequent as that reported from Italy, which was 3.3 per 100 000 in 1993 [3]. It was more comparable to that reported in France, which was 16.2 per 100 000 per year in those aged 1080 years for the period 1986 to 1990 [4]. In children, the biopsy rate was four times as frequent as that from Italy, which was 1.7 per 100 000 per year for the period 19921994 [5]. In Australia there has been a liberal renal biopsy policy. Indicators for renal biopsy include non-urological haematuria, proteinuria and renal impairment, as well as the more specific presentations of glomerulonephritis such as nephrotic or nephritic syndrome.
In adults, the annual incidence of IgA disease has been reported to be between 0.4 and 3.1 per 100 000, and that of focal glomerulosclerosis between 0.1 and 0.9 per 100 000, in several studies [3,4,68]. The annual incidence of lupus nephritis has been reported at 0.3 per 100 000 in Italy; however, this included children and adults together [3]. These rates are all lower than that found in this review for adults. The annual incidence of primary renal vasculitis in adults was very similar to that reported from a population-based registry in the UK, at 1.8 per 100 000 for the period 19921997 [9]. The male to female ratio was identical, at 1.7. These rates are higher than those previously reported in European studies [3,1013], but are not as high as those reported in Kuwait [14].
In children, the annual incidence of IgA disease or Henoch-Schonlein purpura nephritis has been reported at 0.5 per 100 000, minimal change disease at 0.2 per 100 000, focal glomerulosclerosis at 0.1 per 100 000 and lupus nephritis at 0.1 per 100 000, from the Italian Registry of Renal Biopsies [5]. Again, these rates are all lower than that found in this review for children. In addition, unlike the Italian registry data, this review found that lupus nephritis and focal glomerulosclerosis were the most common diseases diagnosed by renal biopsy in children.
Notable patterns of disease identified in this review included the male predominance of biopsy-proven glomerulonephritis for all histological categories, with the exception of lupus nephritis in both adults and children. In addition, an increase in the incidence of disease with age, particularly in males, was seen for vasculitis and focal glomerulosclerosis. The peak age-specific incidence is similar in males and females for lupus nephritis (2534 years), focal glomerulosclerosis (5564 years), membranous nephropathy (5564 years) and vasculitis (6574 years). For IgA disease, however, the age-specific incidence peaks at a younger age in females (2534 years) compared with males (5564 years). These findings suggest the potential role of age- and gender-specific environmental exposures, such as infective, dietary or occupational exposures, in the aetiology of these renal diseases.
The most common causes of biopsy-proven glomerulonephritis (IgA disease, focal glomerulosclerosis, lupus nephritis, vasculitis and membranous nephropathy) were also the most common causes of end-stage renal disease due to glomerulonephritis. Although non-concurrent, with biopsy-based data reflecting relatively newly diagnosed renal disease, and the registry-based data of uptake onto the end-stage renal disease programme reflecting renal disease which is more progressed in its natural history, the similar proportions of the glomerulonephritides indicates the clinical and public health importance of the renal disease identified on biopsy.
While true variation may exist between populations, differences in biopsy rate, referral patterns, indications for renal biopsy and classification criteria for histological diagnosis of renal biopsies may at least in part explain the observed geographical variations. The absence of this information in this study, due to its retrospective nature, limit comparisons with data from other countries. However, the data collected in this review in relation to age and sex distribution provides important insights into potential risk factors for the various glomerulonephritides for further study, an area of research which to date has been limited.
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Acknowledgments |
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Notes |
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References |
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