The effect of fibrinoid necrosis on the clinical features and outcomes of primary IgA nephropathy

Background: To explore the clinicopathologic features and outcomes of IgAN patients who presented with fibrinoid necrosis (FN) lesions or not and the effect of immunosuppressive (IS) treatment in IgAN patients with FN lesions as well. Methods: : This was a retrospective cohort study with 720 patients diagnosed with primary IgAN from January 2010 to December 2020 in Tianjin Medical University General Hospital and having detailed baseline and follow-up characteristics. Explore the difference of clinicopathological characteristics in different group IgAN patients. Compare the survival from a composite endpoint rate in different group IgAN patients by Kaplan-Meier survival curve as well. The univariate and multivariate Cox models were used to establish the basic model for renal outcomes in patients with FN lesions. Results: : (1) A total of 233 patients (35.04%) were found FN lesions in all participants. Patients with FN lesions suffered more severe hematuria than those without. On the hand of pathological characteristic, patients with FN lesions showed higher proportions of M1, E1, C1/C2 and T1/T2 lesions compared with those without FN lesions. (2) The 1-year, 3-year, and 5-year survival of the composite endpoint were lower in the FN1 group than FN0 group. By contrast, patients showed no statistical significance on the survival of the composite kidney endpoint between patients with or without FN lesions after IS treatment. (3) After adjusting for clinicopathological variables, the presence of FN lesions was a significantly independent risk factor for composite endpoint. By using multivariate Cox regression analyses, we also found when the fraction of FN lesions exceeded 10%, the risk of progression into composite endpoint increased 3.927 times. Conclusion: Fibrinoid necrosis of capillary loops is an independent risk factor of poor renal outcomes. More effective treatment like IS treatment should be considered for those who had FN lesions.