目前LOB、LoD概念整体上已经基本达成共识，但是在具体概念细节上，其实还是存在一些会引发歧义的内容。
因此在展示LOB指标的时候，还是尽量在结果展示阶段，说明具体的计算方法或参考资料。以避免引起一些不必要的问题。
Limit of Blank (LoB)
A blank sample was defined as a sample containing a single genotype (i.e pre-transplantation samples). The average measured background of a second genotype in blank samples detected in the informative markers for all theoretical combinations of pairs was defined as LOB. [1]
LoB is the highest apparent analyte concentration expected to be found when replicates of a blank sample containing no analyte are tested. LoB = mean-blank + 1.645(SD-blank) . The raw analytical signal is preferable for establishing LoB as analysers may report all signal values below a certain fixed limit as “zero concentration”).[2]
Limit of Detection (LoD)
LOD was defined as the lowest chimerism value that could be reliably distinguished from the LOB.[1]
LoD is the lowest analyte concentration likely to be reliably distinguished from the LoB and at which detection is feasible. LoD is determined by utilising both the measured LoB and test replicates of a sample known to contain a low concentration of analyte. LoD = LoB + 1.645(SD low concentration sample) [2]
Limit of Quantitation (LoQ)
The LOQ represents the lowest measured MC according to a predefined accuracy goal. We defined the LOQ as the lowest level of MC measured at or above the LOD with CV<20%. [1]
LoQ is the lowest concentration at which the analyte can not only be reliably detected but at which some predefined goals for bias and imprecision are met. The LoQ may be equivalent to the LoD or it could be at a much higher concentration.[2]
参考文献
- Development and performance of a next generation sequencing (NGS) assay for monitoring of mixed chimerism
- Limit of Blank, Limit of Detection and Limit of Quantitation
- [高通量测序技术，主编：李金明]
- Method Validation Essentials, Limit of Blank, Limit of Detection and Limit of Quantitation
- FDA-SUMMARY OF SAFETY AND EFFECTIVENESS DATA
- Protocols of determining limits of detection and limits of quantitation for quantitative analytical methods
- FDA:Test Developers of Serology Tests that Detect or Correlate to Neutralizing Antibodies