Supplementary Material for: Performance of a Novel Research-Use-Only Secretoneurin ELISA in Patients with Suspected Acute Coronary Syndrome: Comparison with an Established Secretoneurin Radioimmunoassay

<b><i>Background:</i></b> Circulating secretoneurin (SN) concentrations, as measured by established radioimmunoassay (RIA), risk stratify patients with cardiovascular disease. We now report data for a recently developed research-use-only SN enzyme-linked immunosorbent assay (ELISA) in patients with suspected acute coronary syndrome (ACS). <b><i>Methods:</i></b> SN ELISA was developed according to industry standards and tested in 401 unselected chest pain patients. Blood samples were drawn &lt;24 h from admission, and we adjudicated all hospitalizations as ACS or non-ACS. The mean follow-up was 6.2 years. <b><i>Results:</i></b> SN ELISA with 2 monoclonal sheep anti-SN antibodies has a measuring range of 10–250 pmol/L and demonstrates excellent analytical precision and accuracy across the range of SN concentrations. SN measured by ELISA and RIA correlated in the chest pain patients: rho = 0.39, <i>p</i> &lt; 0.001. SN concentrations were higher in ACS patients (<i>n</i> = 161 [40%]) than in non-ACS patients (<i>n</i> = 240) for both assays, with an area under the curve (AUC) of 0.66 (95% CI: 0.61–0.71) for ELISA and 0.59 (0.54–0.65) for RIA. SN concentrations were also higher in nonsurvivors (<i>n</i> = 65 [16%]) than survivors, with an AUC of 0.72 (0.65–0.79) for ELISA versus 0.64 (0.56–0.72) for RIA, <i>p</i> = 0.007, for difference between assays. Adjusting for age, sex, blood pressure, previous myocardial infarction, atrial fibrillation, and heart failure in multivariable analysis, SN concentrations as measured by ELISA, but not RIA, remained associated with mortality, with a hazard ratio of 1.71 (1.03–2.84), <i>p</i> = 0.038. <b><i>Conclusions:</i></b> The novel SN ELISA has excellent performance, higher AUC for diagnosis, and superior prognostic accuracy compared to the established RIA in chest pain patients.

**_背景：_** 采用成熟放射免疫分析法（radioimmunoassay，RIA）检测的循环分泌神经素（secretoneurin，SN）浓度，可对心血管疾病患者进行风险分层。本研究报告了一款新近研发的仅用于科研的SN酶联免疫吸附试验（enzyme-linked immunosorbent assay，ELISA）在疑似急性冠状动脉综合征（acute coronary syndrome，ACS）患者中的检测数据。
**_方法：_** 本研究按照行业标准研发了SN ELISA，并在401例未经挑选的胸痛患者中开展检测。于患者入院24小时内采集血液样本，将所有住院患者判定为ACS患者或非ACS患者，平均随访时长为6.2年。
**_结果：_** 采用2株单克隆羊抗SN抗体构建的SN ELISA检测范围为10~250 pmol/L，且在所有SN浓度区间内均展现出优异的分析精密度与准确度。胸痛患者中，ELISA与RIA检测的SN浓度具有相关性：斯皮尔曼相关系数ρ=0.39，P<0.001。两种检测方法均显示，ACS患者（n=161，占比40%）的SN浓度高于非ACS患者（n=240）；ELISA检测的曲线下面积（area under the curve，AUC）为0.66（95%置信区间：0.61~0.71），RIA检测的AUC为0.59（0.54~0.65）。非存活患者（n=65，占比16%）的SN浓度亦高于存活患者；ELISA检测的AUC为0.72（0.65~0.79），RIA检测的AUC为0.64（0.56~0.72），两种检测方法的AUC差异具有统计学意义（P=0.007）。在校正年龄、性别、血压、既往心肌梗死史、心房颤动及心力衰竭的多变量分析中，ELISA检测的SN浓度与死亡率仍具有相关性（风险比HR=1.71，95%置信区间：1.03~2.84，P=0.038），而RIA检测的SN浓度则无此关联。
**_结论：_** 与成熟的RIA相比，这款新型SN ELISA在胸痛患者中展现出更优异的检测性能、更高的诊断曲线下面积以及更出色的预后预测准确性。