There are definitely use cases involving modifiers, so the fields should not be removed. Instead the “qualifier_source_value” should be renamed to “modifier_source_value”. I do not know of any other use case these fields would be used for, besides modifiers. From a claim perspective, modifiers are the only fields that would be used.
For @Patrick_Ryan and @Christian_Reich, here are some use cases to consider when using U.S. claims data:
- Identifying a procedure performed by an assistant surgeon (using modifier 80). If a surgery involved a surgeon and assistant surgeon, both doctors would submit a claim with the same procedure codes. However, the assistant surgeon would use modifer 80 to denote that his procedures were “assists” and should only be reimbursed at 25% of the fee schedule. Since US claims data does not usually give us de-identified physician information (and most users are not ETL’ing the physician information in the first place because of this), there would be no way to determine why a patient has duplicate procedure codes for the same visit. Was it a bilateral procedure and the patient had two procedures done on both sides? Were two physicians working only on one surgery? Which procedure was primary and which one was from the assist? We won’t know this information unless we knew the modifier. You might be able to infer some information by looking at the related costs, but that is very tricky when looking at private vs Medicare claims due to different fee schedules.
- As @Christian_Reich alluded to in a previous reply, modifiers denote bilateral procedures vs one-sided procedures. Bilateral procedures use a modifer 50. This is used heavily in eye surgeries (i.e. cataract surgery). If you are doing any epi work, and want to identify how many “eyes” had cataract surgery, you need to double count procedures with a modifier 50. You might be able to figure it out using the associated cost of the procedure, but again, that is a tricky slope since fee schedules are different across providers (for private claims) and geographic areas (for Medicare claims). So obviously, if you remove the modifier field, you would not get the “modifier 50” information for eye procedures, and you would be under counting the number of “eyes” that had surgery.
To answer @burrowse vocabulary question, yes there is a vocabulary for modifiers. If you look under concept_class_id “CPT4 Modifier” and “HCPCS Modifier” under the concept table, you should find them. And just a reminder that there are two different types of modifiers - CPT and HCPCS. Common CPT modifiers include LT and RT to show procedures being performed on the “left” or “right” side of the patient’s body. You will not see these modifiers in Medicare data.
To address @Mark_Danese’s reply, I do think the modifier information should be in the procedure_occurrence table, not the procedure_cost table or anywhere else. Since these modifiers give more information about the procedure itself. Now they do affect reimbursement in some ways. But in my “modifier 50” example above, there is an epi use case for them. And it would seem that epi analysts would rarely venture into any cost table for data. But coming from a health econ perspective, I could be wrong. But since the modifier field is in the procedure_occurrence table now, why change it?
Some things to note, which I’m probably going to post as a different topic on the forums, but since we’re talking about modifiers, this seems appropriate. US claims can now be submitted with up to 8 modifiers per procedure. However, in the data we have received from data providers, it seems we only get up to the first 4 modifiers. But CDMv5 only has the ability to store one modifier. So the person doing ETLs would have to make an executive decision as to what modifier to keep in the CDM and throw out all of the other data. Or the ETL person could duplicate the procedure and put a different modifier on each one. But that seems way more confusing for an analyst. I’m just bringing this up as an issue and don’t have a resolution yet. But if actual claims are being sent with up to 8 modifiers, it is reasonable to assume that claims data for researchers will also get more than the 4 modifiers eventually. And the CDM will have to be revisited at some point.