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Proficiency Test Scoring

CMS and accreditation organizations routinely monitor their laboratories' performances every 30-45 days. The laboratory director is required to review, evaluate and document (sign the PT Performance Summary report) for each PT event. 

Always review your results with your co-workers and your director. Your PT program will include an evaluation for each of the five challenges for each test or analyte in the PT event and will detail the performance of each test system used by the laboratories enrolled with their program. This must be done for all PT results, even those with passing scores. If you receive an 80% score, you must investigate why one of the five samples was outside the acceptable range of results. Document your investigation and what you did to correct the problem that caused the challenge failure.

Re-review the results that were submitted to the PT program for scoring for any obvious errors (this should have been done prior to submitting your results to the program). Clerical or transcription errors are considered incorrect results. The director of your laboratory as well as the personnel who performed the testing of the PT samples should compare their PT results with the inter-laboratory comparison evaluations provided by the PT program. You must take remedial actions, i.e., determine the cause of the error or errors, correct it (them), and document your actions. Continually monitor the test system performance, review the results of the quality control materials, and discuss with your director to be certain the test system is operating properly and producing accurate results. Your director may want to review the results of the patients tested during the unsatisfactory or unacceptable testing event. Depending upon the test system’s performance and your director’s decision, you may need to contact the manufacturer of the test system for assistance.

If the laboratory has failed to obtain the acceptable score set by the PT program, the State Agency will recommend enforcement actions to the CMS Regional Office (RO) for failure to meet PT requirements for successful participation.

The following terminology is used in the Statement of Deficiency (SOD) reports sent by the State Agency when an unsuccessful performance occurs.

Unsatisfactory PT Performance 

Unsatisfactory PT performance means failure to attain the minimum satisfactory score for an analyte, test, subspecialty, or specialty for a testing event. The laboratory must address the failure, record corrective and remedial actions. All records are retained for two years. The surveyor will review these records and documents during the survey.

Unsuccessful PT Performance

Unsuccessful participation in PT means any of the following:

  1. Unsatisfactory performance for the same analyte in two consecutive or two out of three testing events.
  2. Repeated unsatisfactory overall testing event scores for two consecutive or two out of three testing events for the same specialty or subspecialty. 
  3. An unsatisfactory testing event score for those subspecialties not graded by analyte (that is, bacteriology, mycobacteriology, virology, parasitology, mycology, compatibility testing, unexpected antibody detection, antibody identification) for the same subspecialty for two consecutive or two out of three testing events.

Unregulated analytes

The laboratory must verify the accuracy of the test or procedure twice annually, including the accuracy of calculated results, if applicable, for any test or procedure not listed in Subpart I and/or for which compatible proficiency testing samples are not offered by a CMS approved PT program.

This can be achieved by:

  • Blind testing of materials with known values
  • External assessment programs 
  • Splitting patient samples with another laboratory, instrument or method 
  • Comparison of Kodachrome slides from a reference laboratory

Perform PT on the tests (many PT programs offer limited number of PT samples for “unregulated” tests), but never send out the PT samples out of the laboratory for any reason. Depend on the score provided by the PT program to determine accuracy.

An example of how to check the accuracy of testing not listed in Subpart I is to split a patient’s specimen (never split a PT sample) with another laboratory that offers the same test(s). Your director should review your results and the other laboratory’s results for acceptability.