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CPT4 and HCPCS Procedure Modifiers

Are there a separate set of CPT4 and HCPCS procedure modifiers or is there one set of procedure modifiers that are applicable to both CPT4 and HCPCS codes? How has the vocabulary addressed this? My Googling comes up with

  • Level I Modifiers: Normally known as CPT Modifiers and consists of two numeric digits and are updated annually by AMA American Medical Association.
  • Level II Modifiers: Normally known as HCPCS Modifiers and consists of two digits (Alpha / Alphanumeric characters) in the sequence AA through VP. These modifiers are annually updated by CMS - Centres for Medicare and Medicaid Services

Vocabulary seems to have duplicated procedure modifiers in the CPT4 and HCPCS vocabularies. Can some describe how procedure modifiers should be applied and mapped?

As they come from the same official source and represent full duplicates (e.g. the codes and the names are the same) I’d simply use the modifiers according to their vocabularies. So, if you have CPT4 in your source data you would use CPT4 modifiers and HCPCS modifiers for HCPCS. And this is how the vendors would typically use them: they would use HCPCS modifiers if they use HCPCS vocabulary for billing.
If you have another vocabulary in your source data, I believe both are possible as long as you stick to one.

Well, why not to map them?
HCPCS to CPT4 modifiers, or vice versa? not sure which vocabulary is “more standard”.


There is a Themis job around it. Not sure where they are. Not part of the release I think. Let’s find out.

we’re thinking about NOT using CPT4 and HCPCS vocabularies for the modifier_concept_id mapping in the PROCEDURE_OCCURRENCE table - and instead, use qualifiers in SNOMED …thoughts? thx !

How does your source data code modifiers? Do they use HCPCS, CPT4, SNOMED or a custom vocabulary?

Yeah. There is an urgent need to clean up the Modifiers. They are a mess: Many HCPCS shares the CPT4 modifiers, but they are differently mapped and badly mapped, there is a lot of junk unrelated to patient data (Dmepos item subject to dmepos competitive bidding program that is furnished by a hospital upon discharge). We’ll do a consolidation workshop and come up with a solution. They have been popular with the community, lately. :slight_smile:

Let’s also touch them in OPCS4. They’re not located, can be used in coding as a mixture with the real procedures.

44517228 Z94.3 Left sided operation Procedure Standard Valid Procedure OPCS4
46233622 Z93 Other veins of pelvis Body Structure Standard Valid Spec Anatomic Site OPCS4

Was anything decided regarding modifiers?

I’m struggling to understand how to deal with modifiers that are assigned to different domains based on concept class (i.e., CPT4 modifier v. HCPCS modifier). I wasn’t able to infer a justification for different domains based on CPT and HCPCS codes in our source data associated with these modifiers.

Here’s a breakdown of domain assignment for the 148 modifiers (of 400+) that have different domains based on concept class:

Is this by design, or just part of the vocabulary that still needs a little TLC?