What have we learned from coagulation laboratory participation in external quality programs?

Coagulation laboratory external quality assurance (EQA) programs provide information that satisfies regulatory requirements and improves laboratory quality, patient care, and safety. In addition to the value to individual laboratories, data from EQA programs benefits the laboratory community in multiple ways by providing a snapshot of laboratory practice and summarizing the performance of various methods in identifying normal and abnormal specimens and the effects of therapies or interfering substances. This review article aims to summarize and provide examples of some of the important lessons learned from coagulation EQA data, including issues related to non-standardization, imprecision, and the effects of interfering substances.