Background

In this study, we assessed the performance characteristics of a laboratory-developed radioimmunoassay (RIA) to detect N-type voltage-gated calcium channel (N-VGCC) antibodies found in several autoimmune neurologic diseases.

Methods

Four hundred and forty-five (n = 445) sera were evaluated, including 156 sera (50 positive and 106 negative for N-VGCC antibodies) previously tested at Mayo Clinic Laboratories (MCL) and 289 controls (n = 187 disease and n = 102 healthy). Specimens were analyzed with the RIA using N-VGCC labeled with ¹²⁵I-ω-conotoxin GVIA. The RIA was compared to the predicate MCL assay using a tiered positive predictive value (PPV) approach. Other performance characteristics evaluated included specificity, precision, interference, and stability.

Results

Qualitative inter-laboratory agreement based on tiered PPVs was 100% for results >1.00 nmol/L (71% PPV), 48% for results of 0.10–0.99 nmol/L (24% PPV) and 22% for results of 0.04–0.10 nmol/L (19% PPV). Negative results showed 90% agreement (n = 106). Specificity in controls positive for other neural autoantibodies and healthy controls were 87% and 100%, respectively. Acceptable results were observed for other performance characteristics.

Conclusions

Inter-laboratory correlations demonstrate equivalence between assays with some discrepancies between low positive results. Collaborative efforts aimed at assessing the clinical spectrum associated with these antibodies and consensus for harmonizing test performance are required for optimal categorization of patients.

中文翻译：

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用于检测 N 型电压门控钙通道抗体的放射免疫沉淀试验的性能评估

背景

在这项研究中，我们评估了实验室开发的放射免疫分析 (RIA) 的性能特征，以检测在几种自身免疫性神经系统疾病中发现的 N 型电压门控钙通道 (N-VGCC) 抗体。

方法

 评估了四百四十五 ( n = 445) 份血清，包括先前在梅奥诊所实验室 (MCL) 和 289 名对照（n  = 187 种疾病和n  = 102 健康）。使用用¹²⁵ I-ω-芋螺毒素 GVIA标记的 N-VGCC 用 RIA 分析样本。使用分层阳性预测值 (PPV) 方法将 RIA 与谓词 MCL 测定进行比较。评估的其他性能特征包括特异性、精确度、干扰和稳定性。

结果

基于分层 PPV 的实验室间定性一致性对于 >1.00 nmol/L (71% PPV) 的结果为 100%，对于 0.10–0.99 nmol/L (24% PPV) 的结果为 48%，对于 0.04–0.10 的结果为 22% nmol/L (19% PPV)。阴性结果显示 90% 的一致性 ( n  = 106)。其他神经自身抗体阳性对照和健康对照的特异性分别为 87% 和 100%。对于其他性能特征，观察到可接受的结果。

结论

实验室间的相关性证明了检测之间的等效性，但低阳性结果之间存在一些差异。旨在评估与这些抗体相关的临床谱的合作努力和协调测试性能的共识是对患者进行最佳分类所必需的。