Laboratory policies and procedures will include measurands and test methods for which split sample testing will be performed. Specific testing procedures, frequency of split sample testing, and acceptable performance criteria are also included. The laboratory director must approve the established alternative testing policy and procedure.
A sample protocol for split sample testing is found below:
- Determine tests/analytes eligible for split sample testing.
- Select a CLIA-certified facility with an appropriate comparison method for the analyte to be tested or incorporate two in-house instruments or methods of testing. The CLIA certificate and the method must be of the same level or higher than the primary test method.
- An internal, alternate test method may be used as the comparison method if it is compliant with regulatory requirements.
- If the comparison method (instrument/reagents) is not the same as the testing laboratory, establish bias values.
- Determine acceptable levels of performance for comparison of the two methods.
- Verify acceptable quality control results for each analyte prior to testing prior to sample testing.
- Select a minimum of two specimens for analysis and split each specimen into two portions or send out the same sample after analysis by the testing laboratory. Sample analysis must be equivalent to 95% confidence limits. Test additional samples if necessary.
- Store and transport all specimens as per manufacturer’s instructions.
- Test each specimen in the same manner as a patient sample with the primary method and record results.
- Test the split sample with the secondary in-house method or analyzer or forward to the comparison laboratory.
- Record each referred specimen result. Perform bias correction, if necessary.
- Compare the two sets of results for each analyte. Determine if results agree within the acceptable performance range for the particular analyte.
- Repeat testing if not within acceptable limits and document corrective action.
- Verify that corrective action is effective.
- Forward results to the Laboratory director or designee for review and approval.
- Perform split sample analysis a minimum of twice per year
- Retain all documentation for a minimum of two years.
