A Study on Shelf Life Prediction Options Can Help Ensure Accurate Laboratory Results

Every day, laboratorians must provide quality in vitro diagnostic (IVD) results that meet the needs of caregivers and their patients. They are often asked about result variability and must be prepared to explain that some result-to-result variability is inevitable in measurement systems applied to biological specimens. Laboratories must be diligent in preventing step changes when, for example, reagent lots change or the same analyte can be measured on multiple systems. Guidelines are available to handle these situations (1, 2) and the ongoing process of maintaining a quality system (3). A quality process inevitably relies upon regular sampling of QC material and repeating the calibration of assays for specific analytes when problems are detected. Perhaps the most insidious problem within a laboratory quality system is small incremental changes over time caused by the degradation of IVD materials. Like HIV that attacks the very system the body uses to protect itself, the instability of calibrators and QC material attacks the laboratory's quality system. If calibrators degrade, the results from the measurement system move away from “true” values established by traceability to higher-order methods or materials. This change happens at each calibration and may be too subtle for the quality system to detect. If QC material degrades the quality system changes, perhaps triggering concern when the measurement system has not changed. If both calibrators and QC material degrade then either poor outcome is possible. Manufacturers of IVD materials must ensure that their products are stable. Since 2009 they have been guided by EP25-A, (4), which describes best practices for measuring IVD reagent stability in real time (over the time frame to be tested) and with accelerated stability protocols. Although accelerated studies may not be used to establish the published shelf life of a product, they can be used during product development, when …