Proficiency testing performance in US laboratories: results reported to the Centers for Medicare & Medicaid Services, 1994 through 2006.

Context: Beginning in 1994, clinical laboratories performing nonwaived testing were required, under the regulations implementing the Clinical Laboratory Improvement Amendments of 1988 (CLIA), to enroll and participate in a proficiency testing (PT) program approved by the Centers for Medicare & Medicaid Services. Successful PT performance is a requirement for maintaining CLIA certification to perform testing in certain specialties and subspecialties and for specific analytes.

Objective: To evaluate the PT performance from 1994 through 2006 of hospital and independent laboratories (HI) compared with all other testing sites (AOT) for selected commonly performed tests and analytes.