Quality assurance of clinical tests is crucial for patient safety. External quality assessment (EQA) is a procedure for the systematic assessment of the quality of analysis where unknown samples are tested at regular intervals. The aim of EQA is to ensure that test results are reliable and comparable no matter where they are performed.
The central concept behind EQA is the distribution of a stable and consistent sample for participants to analyse. The participant does not know beforehand what results to expect from the analysis. Results are returned to the EQA scheme organiser who then rate your result against the target value. The target value may be that determined by a Reference Laboratory, or may be a consensus value (derived from all results).
Of itself, passive participation in EQA is not enough. Reports must be understood and interpreted correctly so as prompt corrective actions and guide quality improvement.
Internal Quality Control (IQC) assesses, in real time, whether the performance of an analyser or meter is consistent. It involves the routine analysis of a control material and comparison of results with predetermined acceptance limits - patient results should not be reported unless the IQC for that analyte is satisfactory.