A Metric for Quantifying the Resolution of Molecular Assays

Many assay developers focus on limit of detection (LOD) as a primary performance metric, and LOD is indeed useful for assays designed to determine the presence or absence of an analyte. However, LOD is less useful for continuous assays designed to discriminate between concentrations of an analyte--e.g., glucose monitoring in diabetes, where clinical care is guided by particular concentration ranges and thresholds. In such scenarios, it would be valuable to quantify discriminatory resolution--i.e., whether an assay can differentiate 1 pM from 10 pM-- but no such standardized metric currently exists. Here, we propose a useful solution, termed resolution of molecular concentration (RMC). RMC offers a simple means for characterizing quantitative resolution and quickly comparing the quantitative performance of assays. By raising awareness of the limitations of current metrics for evaluating assay performance, we hope to empower the molecular diagnostics community to evaluate their methods in a more application-appropriate manner.