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Because of the risk of this specific error for this specific test, much has been done to decrease the change of this outcome, including the creation of distinct LOINC codes for 4th generation and 5th generation assays and the generation of specific guidelines for troponin assay implementation. However, there are many other laboratory tests that are poorly analytically harmonized that do not have such safeguards in place.
Clinical Scenario 4 Use Case
Current State
A 60 year old male liver transplant patient is receiving care at two healthcare institutions, a large academic medical center about an hour away and a small regional laboratory. On a recent visit to the academic medical center for his transplant care, his physician notices that his creatinine has jumped from 1.2 md/dL to 1.7 mg/dL. The two clinical laboratories perform different tests. Both assays are traceable to an isotope dilution mass spectrometry reference method using the NIST Standard Reference Material 967 and are annotated with the same LOINC code (2160-0). Since the patient is on medications that are potentially toxic to their kidneys, this change prompted concern for acute kidney injury. The patient was urgently admitted to the hospital for monitoring. The patient’s creatinine was found to be stable over the next 24 hours and there was no evidence of acute kidney injury.
Details
Creatinine assays are one of a handful of tests that have been standardized and their results are traceable to reference materials. Despite this, there are substances in patient’s specimens that can lead to erroneous results and the directionality and magnitude of these effects differ assay by assay. The most likely explanation in the above case is that high concentrations of bilirubin and its metabolites led to a method-specific false decrease in the test result at the regional laboratory.
How to encode harmonization
A single binary indicator for harmonization cannot handle this situation well. Either it could be decided that no creatinine results will be treated as equivalent and thereby lose the opportunity for cross-lab monitoring for this important marker of acute and chronic kidney injury. Or it would be decided that all creatinine results from methods that are traceable to an approved reference standard will be treated as equivalent, leading to mismanagement as in this case or potentially inappropriate prioritization of patients on liver transplant listings.
This is one very specific example of a limitation in using a binary indicator for harmonization status. There are many such nuances such that it is extremely challenging to use a binary indicator in a way that is both safe and useful. It also highlights the importance of domain expertise and conscientious governance if decisions will lead to broad adoption.
Research Scenario Use Case
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