Background New immunoglobulin free light chain (FLC) assays are available. Despite analytical differences, it seems possible to use free light chain ratios (FLCr) generated by different assays and apply similar cut-points for the diagnosis of multiple myeloma. It is still unknown if we can use different assays for risk stratification of patients with monoclonal gammopathy of undetermined significance (MGUS). Methods Patients diagnosed with MGUS (N = 923) had FLC tested using a nephelometric FreeLite (Binding Site) assay on BNII instruments (Siemens) and a Sebia FLC assay (Sebia) on a DS2 ELISA analyzer (Dynex). Patients were followed up for progression to any plasma cell dyscrasia (PCD) for several decades. The Mayo MGUS risk stratification model for progression was assessed with both assays (M-spike >1.5 g/dL; non-IgG isotype and abnormal FLCr), using package insert reference intervals (RI) and a new metric called principal component 2 (PC2). Results There were 94 events of progression to PCD in the cohort during a median of 38 years of follow-up. Freelite and Sebia FLC showed similar hazard ratios in the risk models for elevated FLCr. An alternative clinical decision point lower than the package insert RI was evaluated for the Sebia assay, which improved risk stratification for patients with a low FLCr. The PC2 metric showed similar performance to the FLCr in models, without superior benefit. Conclusions The Sebia ELISA-based FLC assay can be employed in an MGUS risk stratification model with similar performance to the original 2005 risk stratification model using the FreeLite assay.

中文翻译：

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2 种游离轻链检测的比较：游离轻链比率作为 MGUS 进展风险因素的表现


背景 新的免疫球蛋白游离轻链 (FLC) 检测方法现已推出。尽管存在分析差异，但似乎可以使用不同测定法产生的游离轻链比率 (FLCr) 并应用类似的切点来诊断多发性骨髓瘤。目前尚不清楚我们是否可以使用不同的检测方法对意义未明的单克隆丙种球蛋白病（MGUS）患者进行风险分层。方法 诊断为 MGUS 的患者 (N = 923) 使用 BNII 仪器 (Siemens) 上的比浊 FreeLite（结合位点）测定法和 DS2 ELISA 分析仪 (Dynex) 上的 Sebia FLC 测定法 (Sebia) 进行 FLC 测试。患者对浆细胞恶液质（PCD）的进展进行了数十年的随访。 Mayo MGUS 进展风险分层模型通过两种检测（M-spike >1.5 g/dL；非 IgG 同型和异常 FLCr）进行评估，使用说明书参考区间 (RI) 和称为主成分 2 的新指标（电脑2）。结果 在中位 38 年的随访期间，该队列中有 94 例进展为 PCD 事件。 Freelite 和 Sebia FLC 在 FLCr 升高的风险模型中显示出相似的风险比。 Sebia 测定评估了低于包装说明书 RI 的替代临床决策点，这改善了低 FLCr 患者的风险分层。 PC2 指标在模型中表现出与 FLCr 相似的性能，但没有优越的优势。结论 基于 Sebia ELISA 的 FLC 测定可用于 MGUS 风险分层模型，其性能与使用 FreeLite 测定的原始 2005 年风险分层模型相似。