Thursday, April 28, 2005

Proficiency Testing Accuracy in the United States

Daniel C. Edson, American Proficiency Institute, 1159 Business Park Dr, Traverse City, MI, USA

Performance Evaluation of clinical laboratories regulated by CLIA 1988.

To study the 10-year performance trends of laboratories enrolled in American Proficiency Institute proficiency testing programs.

American Proficiency Institute, a CMS-approved proficiency testing provider serving the physician office, clinic, and small (< 200 beds) hospital market, studied the performance characteristics and trends of our subscribers over a 10 year period from 1994 to 2004. Failure rates for selected analytes were recorded from proficiency testing results submitted in the initial year of PT requirement by CLIA '88 (1994) and 10 years later (2004).

Performance accuracy for microbiology proficiency samples has steadily improved from 1994 2004. In 1994, 35 % of laboratories failed positive urine cultures compared to 7.3 % in 2004. Over 23 % failed positive N. gonorrhoeae cultures in 1994 compared to 6 % in 2004. Nearly 15 % failed positive throat cultures in 1994 contrasted with less than 3 % in 2004. The percent of failures for Strep A Antigen dropped from 10 % in 1994 to nearly 1 % in 2004. Failure rates for non-microbiology analytes has also improved dramatically for the analytes studied. In 1994, nearly 19 % of laboratories failed Cholesterol compared to 3.2 % in 2004. Similar improvements were seen for Glucose, Sodium, Potassium, Creatinine, HDL Cholesterol, Hemoglobin, and Prothrombin Time; these results are compared with a published CDC study.

We conclude: 1) Failure rates for all analytes studied have declined over 10 years but problem areas exist, and 2) Continuing education is most needed for microbiology laboratories.

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