After calibration of a clinical assay, drifting of QC values can indicate that the clinical assay is slowly trending out of control over time. This is due to a natural loss or gain of signal and the cause is usually undefinable. Drifting could also indicate that a reagent, electronic component, or even the QC itself has experienced degradation. Ultimately, some amount of drift may be acceptable depending on the assay, but at a certain level, significant drift will begin impacting the analytical accuracy of patient results and needs to be addressed.
