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The Incidence of Primary vs Secondary Focal Segmental Glomerulosclerosis: A Clinicopathologic Study
Musab S Hommos1, An S De Vriese2, Mariam P Alexander3
1Division of Nephrology and Hypertension, Mayo Clinic, Rochester, MN.
Objectives:
To describe the change in the incidence rates of primary and secondary focal segmental glomerulosclerosis (FSGS) from 1994 through 2013 in Olmsted County, Minnesota, and to identify the clinical and biopsy characteristics that distinguish primary from secondary FSGS.
Patients And Methods:
Olmsted County adult residents with native kidney biopsy from January 1, 1994, through December 31, 2013, and FSGS as the only glomerulopathy were identified. The clinical and pathologic characterstics of primary and secondary FSGS were described and compared, and incidence rates were calculated.
Results:
Of 370 adults biopsied, 281 had glomerular diseases, of which 46 (16%) had FSGS. From 1994-2003 to 2004-2013, there were significant increases in kidney biopsy rates (14.7 [95% CI, 12.1-17.3] vs 22.9 [95% CI, 20.0-25.7] per 100,000 person-years, 17% increase per 5 years; P<.001) and total FSGS rates (1.4 [95% CI, 0.6-2.2] vs 3.2 [95% CI, 2.1-4.3] per 100,000 person-years, 41% increase per 5 years; P=.02). Compared with patients with limited foot process effacement (<80%), patients with diffuse effacement (≥80%) without an identifiable cause had lower serum albumin levels (P<.001), had higher proteinuria (P<.001), and were more likely to have nephrotic syndrome (100% vs 4%; P<.001). Patients with diffuse effacement without an identifiable cause were classified as primary FSGS, which accounted for 3 of 12 patients (25%) during 1994-2003 and 9 of 34 (26%) during 2004-2013.
Conclusion:
Although the incidence of FSGS has increased, the proportions of primary and secondary FSGS have remained stable.
Insights
The incidence of focal segmental glomerulosclerosis (FSGS) increased significantly from 1994-2013. However, the proportions of primary and secondary FSGS remained stable during this period.
Area of Science:
- Nephrology
- Glomerular Diseases
- Epidemiology
Background:
- Focal segmental glomerulosclerosis (FSGS) is a leading cause of kidney disease.
- Understanding trends in FSGS incidence and subtypes is crucial for public health.
- Previous studies have not fully characterized long-term changes in FSGS rates.
Purpose of the Study:
- To determine the changes in incidence rates of primary and secondary FSGS.
- To identify clinical and biopsy characteristics differentiating primary from secondary FSGS.
- To analyze FSGS trends in Olmsted County, Minnesota from 1994-2013.
Main Methods:
- Retrospective analysis of adult native kidney biopsies from Olmsted County, MN (1994-2013).
- Inclusion criteria: FSGS as the sole glomerulopathy.
- Calculation of incidence rates and comparison of clinical/pathologic features.
Main Results:
- Kidney biopsy rates increased by 17% per 5 years, and total FSGS rates increased by 41% per 5 years.
- Patients with diffuse foot process effacement (primary FSGS) showed lower serum albumin, higher proteinuria, and higher rates of nephrotic syndrome.
- Primary FSGS accounted for 25% of cases in 1994-2003 and 26% in 2004-2013.
Conclusions:
- The incidence of FSGS has significantly increased over the past two decades.
- Despite the rising incidence, the relative proportions of primary and secondary FSGS have remained consistent.
- Clinical and biopsy findings help distinguish primary from secondary FSGS, with diffuse effacement indicating primary disease.
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