Clinical Implications of C2 Lesion in IgA Nephropathy: A Cohort Study.

Introduction: In 2016, the Oxford Classification of IgA nephropathy (IgAN) updated its scoring system for the glomerular crescents. Despite this, the clinical significance of crescentic lesions in the updated Oxford classification is still unexplored through prospective cohort studies.

Methods: 134 patients diagnosed with IgAN accompanied with C2 lesions at Peking University First Hospital were consecutively enrolled and prospectively followed up for analysis. Multivariate Cox regression in combination with LASSO regression was used to analyze risk factors associated with end-stage kidney disease (ESKD).

Results: During biopsy, the mean estimated glomerular filtration rate (eGFR) was 39.3 mL/min/1.73 m2, and the mean proteinuria was 4.4 g/day. The proportion of kidney failure at 1 year, 2 years, and 3 years were 24%, 34%, and 47%, respectively. The results of LASSO in combination with Cox regression showed that mean arterial pressure (hazard ratio [HR] = 1.035, 95% confidence interval [95% CI] 1.013-1.056, p = 0.001), eGFR at biopsy (HR = 0.968, 95% CI [0.948-0.990], p < 0.004) and T2 lesions (HR = 2.490, 95% CI [1.179-5.259], p = 0.017) were independent risk factor associated with ESKD in patients with C2 lesions. Furthermore, based on univariate analyses, we found that patients with kidney function declined more than 50% within 3 months prior to biopsy or pathological findings indicated a proportion of crescents exceeding 50% were both associated with a poor kidney prognosis. Lastly, when the proportion of the crescent was less than 50%, patients receiving combined steroid and immunosuppressant treatment did not exhibit a better renal prognosis than those receiving steroid only.

Conclusion: Patients diagnosed with IgAN and concurrent C2 lesions exhibited a poor clinical prognosis, necessitating more effective treatment strategies.