Understand PT Scoring Rules
PT provides three shipments (testing events) per
year. Each shipment contains five samples for each test (analyte) performed,
except for microbiology where a combination of 5 tests per shipment is allowed.
To pass a PT event, a laboratory needs a score of at least 80% (4 out of 5
correct responses) for each analyte. Labs must also attain a minimum of 80% for
each specialty (chemistry, hematology, etc.) as well as a total event score of
at least 80%. Some critically significant tests such as blood grouping and
typing require a 100% score to pass.
Overall PT performance is determined by the “two out
of three” rule. A laboratory that fails two consecutive or two of three testing
events is “unsuccessful” and subject to sanctions. Technically, sanctions for unsuccessful PT include voluntary
withdrawal of a laboratory’s CLIA certificate for the specialty, subspecialty
or test. This prohibits testing some or all of the failed analytes by any method. By passing two subsequent
consecutive PT events, a lab may have its certificate reinstated, and may
resume testing.
If the two out of three rule is broken, most likely
a HCFA/COLA inspector will contact you to ensure that the cause for failure was
determined and that remedial action was taken. If not, you may be required to
submit a plan of correction and be subsequently monitored by additional PT or
an on-site inspection to evaluate progress.
Enroll For The Correct Tests
CLIA mandates that laboratories subscribe for every
"regulated" non-waived test performed where a PT program is
available. A list of regulated analytes is in the February 28th, 1992 Federal Register.
Follow PT Directions to the
“T”
Most PT failures are due to factors other than
analytical problems with a test or an instrument. These controllable conditions
include incorrect dilutions or clerical mistakes such as transposing numbers
onto the answer block, not completely filling out the report form, or not
returning results before the due date.
Testing Proficiency Samples
Handle PT specimens exactly like patient specimens
to the extent possible, i.e., test the same amount of times as patient
specimens using the same instrument or kit used for patient specimens. Repeat a
PT test only if a patient sample with that value would have been repeated.
Never send PT samples to a commercial laboratory! Document all steps in the
proficiency testing process including the date samples were received, date
tested, lot numbers of reagents used, and the person who performed the test.
This information will be invaluable when investigating the cause of a PT
failure.
Investigating
PT Failures
Investigate PT failures as soon as an unsatisfactory
score is received. Gather all PT records and try to determine the probable
cause. Some serum-based PT samples can be stored frozen and retested if failure
occurs. Even if the cause of PT failure can’t be pinpointed, document all
investigative actions on the Proficiency Testing Failure Review Log. Take
corrective action before the next PT event to avoid breaking the two out of
three rule. Examples of corrective action are calibrating at more frequent
intervals, reducing the acceptable control range, or retraining an employee.
Retaining PT
Records
Save all PT records for at least two years.