The Proportion of New-Onset Microangiopathic Lesions in IgA Nephropathy is Increased After COVID-19 Pandemic in China.

Abstract

Rationale & objective: New-onset IgA nephropathy (IgAN) and thrombotic microangiopathy (TMA) cases were reported after COVID-19 pandemic. This study investigated the prevalence and characteristics of IgAN-MA lesions in IgAN after the COVID-19 pandemic in China.

Study design: A cross-sectional study.

Setting & participants: A total of 22,123 biopsied patients, mainly in northern China from June 1, 2018, to May 31, 2024 were enrolled.

Exposure: COVID-19 pandemic in China.

Analytical approach: Cochran-Armitage trend test was used to detect trends of IgAN and MA lesions after COVID-19 pandemic. Stage 1 represented no COVID-19 infection (including Stage 1A); Stage 2 represented possible COVID-19 infection and vaccination implemented; Stage 3 represented COVID-19 infection (including Stage 3A and Stage 3B). Multivariate logistic regression was used to analyze risk factors of MA lesions.

Results: The proportion of IgAN in total biopsies and MA lesions in IgAN showed an increasing trend over time. In Stage 1, IgAN comprised 22.6% of total biopsies, significantly lower than the proportion in Stage 3 (24.5%; P = 0.01) after bias adjusted. The MA lesions increased notably from 3.6% in Stage 1 to 10.1% in Stage 2 and continued to increase to 15.4% in Stage 3 (P < 0.001). Immunofluorescence showed a progressive increase in C3 deposition in patients with IgAN and patients with MA in Stage 1A, Stage 3A, and Stage 3B (all P < 0.05). Multivariable logistic regression identified pandemic exposure, increased mean arterial pressure, lower estimated glomerular filtration rate, S1 lesions, and T1/T2 lesions as risk factors for the development of MA lesions.

Limitations: Proportion based on patients in northern China, diagnosis from medical records without re-evaluation, lack of exact data on vaccination status and COVID-19 infection, lack of prognosis.

Conclusions: COVID-19 may promote the proportion of IgAN in total biopsy and MA lesions in IgAN. Complement activation may play an important role in the development of IgAN and MA lesions.