Introduction

We evaluated the Roche Elecsys IL6 assay on the Cobas immunoassay analyser.

Method

Serum IL6 of 144 controls were compared to 52 samples from patients with COVID-like respiratory symptoms (17 SARS-CoV-2 RT-PCR positive); 25 of these were from the intensive care unit (ICU). We compared the IL6 levels to C-reactive protein (CRP) and procalcitonin (PCT) levels in all cases.

Results

The IL6 assay had coefficient-of-variation (CV) of 2.3 % (34.1 pg/mL) and 2.5 % (222.5 pg/mL), a limit of quantitation <1.6 pg/mL, and was linear from 1.6 to 4948 pg/mL. There was a significant difference in IL6 values between patients with COVID-like respiratory symptoms versus controls (p < 0.001). ROC analysis showed that IL6 > 6.4 pg/mL identified symptomatic cases (AUC 0.94, sensitivity 88.2 %, specificity 97.2 %). There was a significant difference between the IL6 of symptomatic ICU/non-ICU cases (median IL6 228 vs 11 pg/mL, p < 0.0001); ROC analysis showed IL6 > 75 pg/mL (sensitivity 76.0 %, specificity 88.9 %) was superior to CRP and PCT in predicting ICU admission (AUC: IL6 0.83, CRP 0.71, PCT 0.82).

Conclusion

The performance of Elecsys IL6 assay is in keeping with the manufacturer’s claims. IL6 > 6.4 pg/mL differentiates healthy from suspected COVID-19 cases and appears to be raised earlier than the other inflammatory markers in some cases. IL6 > 75 pg/mL was a good predictor of ICU admission.

中文翻译：

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罗氏 IL-6 化学发光免疫测定法在 COVID 样呼吸道症状患者中的表现

介绍

我们在 Cobas 免疫测定分析仪上评估了 Roche Elecsys IL6 测定。

方法

将 144 名对照者的血清 IL6 与来自具有 COVID 样呼吸道症状的患者的 52 份样本（17 份 SARS-CoV-2 RT-PCR 阳性）进行了比较；其中 25 人来自重症监护病房 (ICU)。我们将所有病例中的 IL6 水平与 C 反应蛋白 (CRP) 和降钙素原 (PCT) 水平进行了比较。

结果

IL6 测定的变异系数 (CV) 为 2.3% (34.1 pg/mL) 和 2.5% (222.5 pg/mL)，定量限 <1.6 pg/mL，并且在 1.6 至 4948 pg/mL 之间呈线性毫升。具有 COVID 样呼吸道症状的患者与对照组之间的 IL6 值存在显着差异（p < 0.001）。ROC 分析表明，IL6 > 6.4 pg/mL 确定有症状病例（AUC 0.94，敏感性 88.2 %，特异性 97.2 %）。有症状的 ICU/非 ICU 病例的 IL6 之间存在显着差异（中位 IL6 228 vs 11 pg/mL，p < 0.0001）；ROC 分析显示 IL6 > 75 pg/mL（敏感性 76.0 %，特异性 88.9 %）在预测入住 ICU 方面优于 CRP 和 PCT（AUC：IL6 0.83，CRP 0.71，PCT 0.82）。

结论

Elecsys IL6 测定的性能与制造商的声明一致。IL6 > 6.4 pg/mL 可区分健康病例和疑似 COVID-19 病例，并且在某些病例中似乎比其他炎症标志物更早升高。IL6 > 75 pg/mL 是入住 ICU 的良好预测指标。