Supplementary Material for: Association of serum activin levels with allograft outcomes in patients with kidney transplant: Results from the KNOW-KT

Introduction: Serum activin A has been reported to contribute to vascular calcification and kidney fibrosis in chronic kidney disease. We aimed to investigate whether higher serum activin levels were associated with poor allograft outcomes in patients with kidney transplants (KT).
Methods: A total of 860 KT patients from KNOW-KT (KoreaN cohort study for Outcome in patients With Kidney Transplantation) were analyzed. We measured serum activin levels at pre-KT and 1 year after KT. The primary outcome was the composite of a ≥ 50% decline in eGFR and graft failure. Multivariable cause-specific hazard model was used to analyze association of 1-year activin levels with the primary outcome. The secondary outcome was coronary artery calcification score (CACS) at 5 years after KT.
Results: During the median follow-up of 6.7 years, the primary outcome occurred in 109 (12.7%) patients. The serum activin levels at 1 year were significantly lower than those at pre-KT (488.2 ± 247.3 vs. 704.0 ± 349.6). When patients were grouped based on the median activin level at 1 year, the high-activin group had a 1.91-fold higher risk (95% CI, 1.25-2.91) for the primary outcome compared to the low-activin group. A one standard deviation increase in activin levels as a continuous variable was associated with a 1.36-fold higher risk (95% CI, 1.16-1.60) for the primary outcome. Moreover, high activin levels were significantly associated with 1.56-fold higher CACS (95% CI, 1.12-2.18).
Conclusion: Post-transplant activin levels were independently associated with allograft functions as well as coronary artery calcification in kidney transplant patients.

引言：已有研究表明，血清激活素A（serum activin A）可参与慢性肾脏病患者的血管钙化与肾纤维化进程。本研究旨在探讨肾移植（kidney transplants, KT）患者血清激活素水平升高是否与不良移植物结局相关。
方法：本研究共纳入来自KNOW-KT（韩国肾移植患者结局队列研究，KoreaN cohort study for Outcome in patients With Kidney Transplantation）的860例肾移植患者。我们分别在肾移植术前及术后1年检测患者血清激活素水平。本研究的主要终点为估算肾小球滤过率（eGFR）较基线下降≥50%与移植物失功的复合事件。采用多变量病因特异性风险模型分析术后1年血清激活素水平与主要终点的关联。次要终点为肾移植术后5年的冠状动脉钙化评分（CACS）。
结果：中位随访6.7年期间，共有109例（12.7%）患者出现主要终点事件。患者术后1年的血清激活素水平显著低于术前水平（488.2±247.3 vs. 704.0±349.6）。根据术后1年血清激活素水平的中位数将患者分为两组，高激活素组患者发生主要终点事件的风险较低激活素组升高1.91倍（95%CI：1.25~2.91）。将血清激活素水平作为连续变量分析时，其每增加1个标准差，患者发生主要终点事件的风险升高1.36倍（95%CI：1.16~1.60）。此外，高血清激活素水平与冠状动脉钙化评分升高1.56倍显著相关（95%CI：1.12~2.18）。
结论：肾移植患者术后血清激活素水平与移植物功能及冠状动脉钙化均独立相关。