Header: MolDx is proliferating the number of separate Z codes that may be used with a single CPT code (even a single PLA code). This allows the Z code to describe patient pre-conditions and scenarios that can't be captured under one code.
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Part One:
Many-to-One Mappings of Z codes to Regular Codes
Z codes date back to 2012, a prehistoric time period when there were only a few molecular codes (such as, "DNA extraction, $20" and "DNA amplification, $20.") Z codes could make such descriptors specific for, say, EGFR mutations.
By 2014, AMA CPT was pouring out more specific codes (one for BRCA, one for EGFR, and so on), and Z codes now allowed MolDx to distinguish between MolDx-approved and MolDx-disapproved LDT versions of tests under each of those early CPT codes.
By 2024 - well, it's 2024 now. MolDx is proliferating the numer of Z-codes, and this allows them to process claims based on very specific patient preconditions or scenario factors exist for a given test.
- While CMS has occasionally ventured into verbose and hyper-specific Z codes (G0023, G0033, with G0023 being a Henry-Jamesian 431 words long), there's never been a profusion of scenario-based codes like Z codes today.
- And it could be that MolDx is just getting started.
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Log on to the DEX code registry and check out recent Z-codes for CareDx. (Actually, you don't see Z codes themselves, but each test page in the registry represents a (hidden) unique Z code).
There's an entry labeled, Allosure Kidney (a donor DNA test) for cause ,and an entry labeled, Allosure Kidney for surveillance.
For Cause - The AlloSure assay is a clinical-grade targeted next-generation sequencing assay that uses 266 single-nucleotide polymorphisms to accurately quantify dd-cfDNA in transplant recipients without separate genotyping of donor or recipient. The assay quantifies the fraction of dd-cfDNA in both unrelated and related donor-recipient pairs and can be completed within 3 days of blood draw, thereby providing the practical turnaround time preferred for management of transplant recipients. The AlloSure assay is performed in the CareDx CLIA laboratory and has received conditional approval by the New York State Department of Health.
For Surveillance - The AlloSure assay is a clinical-grade targeted next-generation sequencing assay that uses 266 single-nucleotide polymorphisms to accurately quantify dd-cfDNA in transplant recipients without separate genotyping of donor or recipient. The assay quantifies the fraction of dd-cfDNA in both unrelated and related donor-recipient pairs and can be completed within 3 days of blood draw, thereby providing the practical turnaround time preferred for management of transplant recipients. The AlloSure assay is performed in the CareDx CLIA laboratory and has received conditional approval by the New York State Department of Health.
Here, the body of the text is similar, although in other cases it could differ. The key convention, the name, is separately coded for "Surveillance" (e.g. quarterly in asymptomatic transplants) and "For Cause" (e.g. to work up signs and symptoms of rejection.)
The text has a different style in the equivalent Natera test, called "Prospera".
Prospera Kidney For Cause, Cell free DNA found in plasma of kidney transplant recipients is isolated, amplified, sequenced, and analyzed to calculate the donor-derived cell-free DNA fraction. This fraction is indicative of kidney status. Assay intended for use as an aid in the for-cause detection of renal allograft injury and rejection.
Prospera Kidney For Surveillance, Cell free DNA found in plasma of kidney transplant recipients is isolated, amplified, sequenced, and analyzed to calculate the donor-derived cell-free DNA fraction. This fraction is indicative of kidney status. Assay intended for surveillance purposes when done as an alternative to surveillance biopsy for renal allograft injury and rejection.
Inivata (a liquid biopsy company now within Neogenomics) has 25 use cases for its RaDaR MDR minimal residual disease detection test, for different diseases (like breast cancer, lung cancer, etc) as well as numerous different use cases and situations. Click to enlarge.
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| 25 Alternate Descriptors for Inivata RaDaR |
I looked at MRD codes of 6 companies, Adaptive, Guardant, Inivata, Natera, Naveris. I tallied 54 total MRD codes, of which about 30 were inactive or nonpayable (perhaps awaiting more data). By my tally, 5 of 25 Inivata codes were rated in DEX as covered, compared to 19 of 22 under Natera.
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| DEX MRD codes (7/2024) |
Could Z-code logic helped shape easier to understand LCDs?
Over the past year, there have been debates in the WSJ about MolDx's coverage regarding donor DNA testing (the saga started in March 2023 and reached WSJ September 10, September 22, September 26, February 22, April 18) and along the way, see also at least one CMS press release (February 29). No question, the CMS coverage for Allosure is more intricate to read than the SC BCBS coverage. Click to enlarge.
MolDx issued a revision of the LCD (DL38568) on August 10, 2023, currently pending finalization. I posted a cloud-copy redline of the draft compared to the prior active version - here. The effective coverage rules are intertwined and reach circa 900 words long in the proposal. MolDx noted in August 2023 that the various revisions (here) were "clarity" only and that "no change in coverage" was implied by the new text and definitions and rules (stated as "synopsis of changes" in DL38568).
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| DL38568 (click to enlarge). Changes for clarity only (per synopsis). |
Could Z Codes Help the LCD Writer?
The Z codes for "surveillance" and "for cause" coverage reveal a basic logical structure that would be difficult for a new reader to quickly extract from the numerous allograft LCD rules.
For example, based on the Z code logic, the LCD coverage structure might be styled as,
"MolDx covers donor DNA transplant tests for rejection for two purposes, "surveillance" and "for cause".
1. "Surveillance" testing is covered when A,B,C,D, and not covered if E, F.
2. "For Cause" testing is covered when G, H, I, J, and not covered if K. L.
This would bring the clarity of coverage statements more into alignment with the structure of the transplant Z codes.
