Dr. Carol Davila Teaching Hospital of Nephrology, University of Medicine and Pharmacy Carol Davila, Bucharest, Romania.
Iran J Kidney Dis. 2020 Dec;14(6):470-477.
Serum immunoglobulin A (IgA)/C3 ratio has been reported as a predictor of histological lesions and prognosis in asian patients with IgA nephropathy (IgAN). Since its validity in other populations is unclear, we aimed to evaluate the relationship between IgA/C3 ratio and renal outcome in Caucasian European patients with biopsy-proven IgAN.
We conducted a retrospective, observational study on 95 patients with primary IgAN patients diagnosed between 2010 to 2017 (70% male, age 41 (34 to 49) years, eGFR 39.4 (25.2 to 56.5) mL/ min, proteinuria 1.7 (0.8 to 3.0) g/g). The primary study composite end-point was doubling of serum creatinine, ESRD (dialysis or renal transplant) or death, whichever came first.
Median follow-up was 30 (95% CI: 27.5 to 32.4) months; 11% developed ESRD, 10% experienced serum creatinine doubling, and 1% died. The endpoint was reached by 21% of the patients. They had lower eGFR, higher proteinuria and hematuria, and lower serum albumin. The distribution in Oxford classes was alike. The AUROC for IgA/C3 ratio was 0.60 (95% CI: 0.45 to 0.74) and generated an optimal cut-off of 2.91 (sensitivity 68%, specificity 55%). The mean event-free survival of the whole cohort was 5.2 (95% CI: 4.7 to 5.8) years. Patients with IgA/C3 ratio < 2.9 had a tendency to better renal survival (P > .05). In Cox proportional hazard ratio model, the independent predictors of a poorer eventfree survival were higher serum creatinine, higher proteinuria and increased IgA/C3 ratio, while renin angiotensin system inhibitors predicted better outcome.
Our study reports evidence that supports IgA/C3 ratio as a reasonable predictor of IgAN prognosis in European patients.
血清免疫球蛋白 A（IgA）/C3 比值已被报道为亚洲 IgA 肾病（IgAN）患者组织学病变和预后的预测指标。由于其在其他人群中的有效性尚不清楚，我们旨在评估 IgA/C3 比值与经活检证实的 IgAN 欧洲白人患者肾结局之间的关系。
我们对 2010 年至 2017 年间诊断为原发性 IgAN 的 95 例患者进行了回顾性、观察性研究（70%为男性，年龄 41（34 至 49）岁，eGFR 39.4（25.2 至 56.5）mL/min，蛋白尿 1.7（0.8 至 3.0）g/g）。主要研究复合终点是血清肌酐加倍、终末期肾病（透析或肾移植）或死亡，以先发生者为准。
中位随访时间为 30 个月（95%CI：27.5 至 32.4）；11%的患者发展为终末期肾病，10%的患者发生血清肌酐加倍，1%的患者死亡。21%的患者达到了终点。他们的 eGFR 较低，蛋白尿和血尿较多，血清白蛋白较低。牛津分类的分布相似。IgA/C3 比值的 AUROC 为 0.60（95%CI：0.45 至 0.74），并产生了 2.91 的最佳截断值（敏感性 68%，特异性 55%）。整个队列的平均无事件生存时间为 5.2 年（95%CI：4.7 至 5.8）。IgA/C3 比值<2.91 的患者有更好的肾脏生存趋势（P>0.05）。在 Cox 比例风险比例模型中，较差的无事件生存的独立预测因素是较高的血清肌酐、较高的蛋白尿和增加的 IgA/C3 比值，而肾素-血管紧张素系统抑制剂预测更好的结果。
我们的研究报告了支持 IgA/C3 比值作为欧洲患者 IgAN 预后合理预测指标的证据。
