Supplementary Material for: Elevated cystatin-C levels are associated with increased mortality in acute coronary syndrome patients: An HIJ-PROPER Sub-Analysis

Background and aims: We investigated the association between serum cystatin-C levels and cardiovascular events in patients with acute coronary syndrome. Methods: Data of 1,100 patients from the prospective parent study were included. Patients hospitalized for acute coronary syndrome were divided into four groups based on quartiles (Q) of cystatin-C levels (mg/L) within 24-hours of admission: Q1, ≤0.82; Q2, 0.821.12. The primary endpoint of this study was all-cause mortality and secondary endpoint was composite of all-cause mortality, non-fatal myocardial infarction, non-fatal stroke, unstable angina pectoris, or ischemia-driven revascularization. Results: During a median observation period of 4.0 years, the primary endpoint was noted in 5, 12, 18, and 36 patients in Q1, Q2, Q3, and Q4, respectively, with corresponding incidence rates of 1.8%, 4.4%, 6.5%, and 13.5%, respectively (p<0.0001 for difference among four groups). This association persisted even after adjusting for patient characteristics and other laboratory results at baseline (p=0.04). A stepwise increase in the incidence rate of the secondary endpoint with an incline in cystatin-C levels was observed in the non-adjusted model (26.6%, 33.3%, 32.3%, and 39.1% in Q1, Q2, Q3, and Q4, respectively; p=0.01), but not in the adjusted model (p=0.3). No difference was observed in the incidence rate of non-fatal myocardial infarction (p=0.89), non-fatal stroke (p=0.3), unstable angina pectoris (p=0.49), and ischemia-driven revascularization (p=0.47) with an incline in cystatin-C levels. Conclusion: Elevated cystatin-C levels were associated with increased all-cause mortality but not cardiovascular events other than mortality in acute coronary syndrome patients.

研究背景与目的：本研究旨在探讨急性冠状动脉综合征（acute coronary syndrome）患者血清胱抑素C（serum cystatin-C）水平与心血管事件的关联。
研究方法：本研究纳入一项前瞻性主研究的1100例患者数据。将因急性冠状动脉综合征住院的患者按入院24小时内检测的血清胱抑素C水平（单位：mg/L）的四分位数（quartiles）分为四组：Q1组≤0.82 mg/L；Q2组0.82~1.12 mg/L；Q3、Q4组按四分位数划分规则顺延确定区间。本研究的主要终点为全因死亡率（all-cause mortality），次要终点为全因死亡率、非致命性心肌梗死（non-fatal myocardial infarction）、非致命性脑卒中（non-fatal stroke）、不稳定型心绞痛（unstable angina pectoris）或缺血驱动的血运重建（ischemia-driven revascularization）的复合终点。
研究结果：中位随访时长为4.0年，Q1、Q2、Q3、Q4组的主要终点事件发生例数分别为5、12、18、36例，对应发生率分别为1.8%、4.4%、6.5%、13.5%（四组间差异P<0.0001）。在校正患者基线特征及基线实验室检测指标后，该关联仍具有统计学意义（P=0.04）。在未校正模型中，次要终点发生率随血清胱抑素C水平升高呈逐步升高趋势（Q1至Q4组发生率分别为26.6%、33.3%、32.3%、39.1%，P=0.01），但在校正模型中该趋势无统计学意义（P=0.3）。不同血清胱抑素C水平分组间，非致命性心肌梗死（P=0.89）、非致命性脑卒中（P=0.3）、不稳定型心绞痛（P=0.49）及缺血驱动的血运重建（P=0.47）的发生率均无显著差异。
研究结论：急性冠状动脉综合征患者中，血清胱抑素C水平升高与全因死亡率升高相关，但与死亡率以外的其他心血管事件无显著关联。