Objective: To understand the reasons for proficiency testing (PT) failures, toward the goal of continuous improvement of laboratory services.
Methods: Laboratories participating in PT of routine chemistry testing provided by the National Center for Clinical Laboratories (NCCL) of China were given 3 schemes for handling PT failures in 2016. If they had unsatisfactory PT performance, they were notified and requested to investigate failure errors and submit data regarding those errors.
Results: Failure types were distributed as follows, per error group: Clerical, 10.2%; Methodological, 16.2%; Equipment, 23.6%; Technical, 37.4%; PT Evaluation, 0.5%; Unexplained, 11.5%; and Other, 0.7%. Reasons unique to the PT process accounted for 15.6% of all reasons. Corrective actions mainly included correcting calibration, maintaining or changing equipment, strengthening reagent management, rewriting procedures, and retraining staff members.
Conclusions: The causes for PT failures relate mainly to laboratory problems, not to the PT process itself. Therefore, PT sponsored by the NCCL is an effective evaluation tool for laboratory performance. Also, laboratories should strive to improve analytical performance.