Reasons for proficiency testing failures in clinical chemistry and blood gas analysis: a College of American Pathologists Q-Probes study in 665 laboratories.

Abstract

To determine the reasons for proficiency testing (PT) failures from 41 chemistry and blood gas analytes using data collected to benchmark performance. Self-administered survey requesting number of challenges by analyte encompassing nine PT events. When the challenge resulted in a self-defined failure, further information was requested concerning the magnitude of the failure (as a standard deviation index) and categorization of the type of failure into six major groups (Methodologic, Technical, Clerical, Survey, Unexplained, or Other) and then into subgroups. Laboratories enrolled in the 1992 College of American Pathologists Q-Probes program. Rate of PT failures and reasons for failure. Proficiency testing data from 670,489 challenges performed in 665 laboratories revealed 9268 (1.4%) unacceptable results. Failure types were distributed as follows: Methodologic, 33.5%; Technical, 17.4%; Clerical, 11.1%; Survey, 7.8%; Unexplained, 25.7%; and Other, 7.4%. Individual analyte PT failure is a common event in the participating laboratories, but failures in successive or alternate events are rare. Analysis of the reasons for failed events indicates that most identified reasons occurred in either the Methodologic or Technical categories (50.9%). Analysis of the failure types suggested investigation pathways based on the magnitude of the failure that could reduce the 25.7% rate of unexplained failures.