Mats Fernström, the National Board of Health and Welfare, Sweden, 2026-05-12 (SWE ID C1078)

Thank you Kristiina for raising the issue with PROCPR 99S90. I've been thinking about it for years without doing anything, mostly because 99S90 has the low impact on the grouping that you describe. 

It was Martti and I who many years ago invented the principle to automatically add 99S90 to certain PROCPR values and then we mostly selected the PROCPR values with the lowest numbers for all MDCs (except 18 and 23). It was somewhat of a "Quick and dirty" principle because none of us had time and energy to assess all thousands of operation codes.  

The principle has worked OK in Sweden, I think, however not automated in our tool, NordDRG Admin. At least there has been no complaints from our NordDRG users, which can also be explained by the fact that 99S90 is involved in very few grouping rules. However, looking at the list of procedure codes with 99S90, there are some codes where 99S90 can be questioned. 

The Swedish DRG team suggests the following: 

The principle to attach 99S90 to certain fixed PROCPR values, and just those, gives us less flexibility if we want to change the grouping logic in the future. That is the main reason why we from now on, when new procedure codes are added to NordDRG, should abandon the principle that some PROCPRs automatically render 99S90. Instead, all new codes should be assessed individually regarding 99S90 (see further down about methods).  Therefore, we agree to change the text for 99S90 to just “Extensive procedure”.

So far, existing codes with 99S90 may in principle keep that property since the system has worked OK, but some revision should be done:  

• Having codes with 99S90 but without OR 1 is contradictory, existing codes with 99S90 should have OR 1. If OR 1 is not appropriate for some reason, 99S90 should be removed. This can be seen as “errors to be corrected”. 
• Existing codes that are missing 99S90 according to the old principle based on certain PROCPR values (7 codes in SWE version) should be assessed individually regarding 99S90 (see further down about methods).  
• Further revisions: For example, percutaneous measures (about 90 codes) should be reviewed. (We doubt that someone in the EG wants to review all the approximately 1 900 codes with 99S90). 

Methodological aspects when assessing whether a procedure should have 99S90 or not 

• We must consider costs for the whole hospital stay, not only for the operation. Even a moderately large operation can sometimes entail large costs for the whole stay. And costs are more important than medical complexity in this context, because the difference between DRG Z50/468 and Z60/477 is mainly the DRG weight, which is based on costs. 
• If the cost for hospital stay with a certain procedure is known, it can be compared with the average costs for DRG Z50/468 and Z60/477. If the cost is closer to the cost for DRG Z50/468 than the cost for DRG Z60/477, then 99S90 can be added to that procedure. 
• If the cost for hospital stay with a new procedure is unknown, we can look for similar procedures in the system and copy the judgement concerning 99S90.  
• If the alternative above isn’t possible, i.e. it is a completely new procedure without known or estimated costs, 99S90 cannot be added to that procedure. The decision about 99S90 must wait until we have cost data.