Department of Central Laboratory and Mitochondrial Medicine Laboratory, Qilu Hospital (Qingdao), Cheeloo College of Medicine, Shandong University, Qingdao, China.
Department of Neurology, Qilu Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China.
Clin Chim Acta. 2022 Aug 1;533:122-130. doi: 10.1016/j.cca.2022.06.017. Epub 2022 Jun 22.
This study aims to establish an optimization procedure to define the cut-offs of quantitative assays for acetylcholine receptor antibody (AChRAb), evaluate their diagnostic performance in myasthenia gravis (MG), and explore the association with clinical features.
Samples from a representative cohort of 77 MG patients, 80 healthy controls (HC) and 80 other autoimmune diseases (OAD) patients were tested using competitive inhibition ELISA and RIA. Raw values (OD and cpm) and processed values (inhibition rate, binding rate and concentration) were used to define the cut-offs with statistical methods, a rough method, and receiver operating characteristic (ROC) curve. Optimal cut-offs were selected by comparing false positive rates in HC and OAD individuals. The diagnostic performance was evaluated in whole MG cohort and subgroups. Agreement between ELISA and RIA for AChRAb positivity were examined with Kappa test and McNemar test. Clinical association with AChRAb was explored by comparison among subgroups and with Spearman rank correlation.
The optimal cut-offs for AChRAb positivity were determined as OD ≤ 1.79 for ELISA and cpm ≥ 1234.12 for RIA, which derived from statistical method and performed better than those derived from ROC curves. The sensitivity and specificity were 74.03%, 100% for ELISA, and 74.03%, 99.37% for RIA. There was good agreement between ELISA and RIA for AChRAb positivity in whole cohort and subgroups (weighted к ≥ 0.71, p < 0.01; McNemar test, p > 0.05). Levels of AChRAb were different in MG subgroups (p < 0.01). Correlation between Quantitative Myasthenia Gravis scores and AChRAb levels was moderate for ELISA and RIA (r = -0.60 and 0.57, p < 0.01).
The raw testing values of ELISA and RIA were found as optimal quantitative measures of AChRAb levels. There are good agreements on diagnostic performance between two assays. Quantitative values are more informative than positivity in association with clinical features.
本研究旨在建立乙酰胆碱受体抗体（AChRAb）定量检测的优化程序，评估其在重症肌无力（MG）中的诊断性能，并探讨与临床特征的相关性。
采用竞争抑制 ELISA 和 RIA 法检测 77 例 MG 患者、80 名健康对照（HC）和 80 名其他自身免疫性疾病（OAD）患者的样本。使用统计学方法、粗略方法和受试者工作特征（ROC）曲线对原始值（OD 和 cpm）和处理值（抑制率、结合率和浓度）进行定义截断值。通过比较 HC 和 OAD 个体的假阳性率选择最佳截断值。在整个 MG 队列和亚组中评估诊断性能。采用 Kappa 检验和 McNemar 检验比较 ELISA 和 RIA 检测 AChRAb 阳性的一致性。通过比较亚组和 Spearman 秩相关探索与 AChRAb 的临床相关性。
ELISA 的最佳截断值为 OD≤1.79，RIA 的最佳截断值为 cpm≥1234.12，这两个截断值来自统计学方法，优于 ROC 曲线得出的截断值。ELISA 的敏感性和特异性分别为 74.03%和 100%，RIA 的敏感性和特异性分别为 74.03%和 99.37%。在整个队列和亚组中，ELISA 和 RIA 检测 AChRAb 阳性的一致性较好（加权 к≥0.71，p<0.01；McNemar 检验，p>0.05）。MG 亚组的 AChRAb 水平不同（p<0.01）。ELISA 和 RIA 的定量肌无力评分与 AChRAb 水平之间存在中度相关性（r=-0.60 和 0.57，p<0.01）。
ELISA 和 RIA 的原始检测值被发现是 AChRAb 水平的最佳定量测量值。两种检测方法在诊断性能上具有良好的一致性。定量值比阳性更能反映与临床特征的相关性。
