Health Care Financing Administration's new proficiency testing rules. Use of a statistical approach to predict long-term performance using the categories 'successful,' 'probation,' and 'suspended'.

Under the Clinical Laboratory Improvement Act of 1967 (CLIA-67) and the Medicare Act, the Health Care Financing Administration's proficiency testing rules apply uniformly to all hospital and reference laboratories. We examined the relationship between internal laboratory performance as characterized by bias and coefficient of variation and proficiency testing performance, categorized as "successful," "probation," and "suspended." Under the March 14, 1990, final rule, a laboratory with suspended testing for even one analyte may be required to cease testing in the entire subspecialty, eg, routine chemistry, unless it ceases testing for that analyte. Analyzing this regimen as a Markov process, we obtained the steady-state solution for performance for one to 27 analytes. While 1.1% of laboratories testing for five analytes with internal or day-to-day coefficients of variation at 50% of the CLIA-67 proficiency testing limit would be suspended, 19.5% of laboratories having biases of 50% and coefficients of variation of 33% would be suspended. We conclude that after eight events, there will be an unacceptably high rate of suspensions.