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Different glomerular diseases have been reported in people with COVID-19 and/or after vaccination against SARS-CoV-2, with the development of collapsing FSGS being observed more frequently in populations with high-risk APOL1 genotypes. However, a causal link between glomerular diseases and COVID-19 infection or its vaccine is not firmly established. To evaluate the real impact of the COVID-19 pandemic on the epidemiology of glomerular diseases, we conducted a retrospective multicenter study analyzing the clinical manifestations and histological findings in renal biopsies during the pre-pandemic and pandemic period.
Patients over 15 years of age who underwent percutaneous renal biopsy of native kidney between 2000 and 2022 in 18 centers in Chile were included. We obtained demographic data, clinical syndrome that led to performing the renal biopsy, laboratory tests, and histological diagnosis. We compare 2 time periods, a pre-pandemic period between 2010 and May 2, 2020, and a pandemic period between May 3, 2020 and December 31, 2022. All biopsies were analyzed by renal pathologists and cases with insufficient histological sample for analysis were excluded. Normality was tested with the Kolmogorov–Smirnov test. Categorical variables were summarized as frequencies and percentages and continuous variables as medians and interquartile ranges. Differences in continuous variables were compared with the use of a Mann–Whitney U test, and categorical variables were compared with the use of the chi-square test. A value of p <0.05 was considered statistical significance. This study was approved by the Ethics Committee.
3502 biopsied patients were analyzed, after excluding cases with insufficient histological sample for diagnosis. The median age was 45 years and 57.8% were female. Overall, the most frequent clinical syndromes that motivated renal biopsy were nephrotic syndrome, alterations in urinalysis, and rapidly progressive renal failure (43.1%; 29.1%; and 11.1% respectively). Comparing both study periods, AKI as an indication for biopsy was more frequent in the pandemic (7.9 vs 6%; p=0.046) and serum creatinine was higher in the same period (1.6 vs 1.39 mg/dL; p<0.01). The frequency of lupus nephropathy, IgAN, membranous nephropathy, minimal change disease, membranoproliferative glomerulonephritis and pauci-immune crescentic glomerulonephritis was similar in both periods analyzed. A trend towards a higher frequency of FSGS was observed in biopsies performed during the pandemic period (p=0.054).
The frequency of glomerular diseases during the COVID-19 pandemic did not vary compared to what was observed before the arrival of SARS-CoV-2. It should be considered that the population studied has a low prevalence of APOL1 Risk Alleles (<0.1%).