DIY ICD-10 conversion – Part 8

February 10th, 2014 / By Ron Mills, PhD

In Part 7 you started with an ICD-9 policy list, and using the “10-to-9 singles map with reverse index” you found all the single ICD-10 codes whose meaning is included in one or more of the ICD-9 codes on your list. In other words, you found all the single codes in ICD-10 that can say what the codes on your ICD-9 policy list say. You wrote those down as a new ICD-10 version of your policy.

In the process, you may have come across … Wait. Is there a hand raised in the back of the class? Yes?

“When you had us write down each ICD-10 code we found using the reverse index, you did not have us write down the ICD-9 code it came from.”

Correct. Why do you think you need to keep track of that?

“Well, my policy concerns the assignment of patients to Care Management programs. Alongside each ICD-9 code on my list, there is the name of one of the five programs we have. For example, alongside 250.00 it says Diabetes, and with 401.0 it says Hypertension, and so on. How will I know which ICD-10 code goes with which program if I don’t keep track of which ICD-9 code it came from?”

Ah, given our definition of a “policy” (a list of ICD-9 codes that collectively mean something), what you have are five policies – one for each Care Management program. Before you start, you have to separate your list into five lists: one for Diabetes, one for Hypertension, and so on. Then you perform the conversion on each list. When you are done, you can put the five ICD-10 lists back together into one spreadsheet if you want, with the program name next to each code.

Another hand: “My policy associates surgery codes with payment levels. In front of each surgery code there is a number from 1 to 7 indicating at which level we pay for the procedure. The actual dollar amounts are updated from year to year. Do I have seven policies then?”

Yes, you do. And something else – I presume a procedure can have one and only one payment level. So what you have is seven mutually exclusive policies. You may have to do some extra work after you finish converting the policies into ICD-10. Unless his patients can be in more than one Care Management program, the gentleman with the five programs will have to do some extra work too. We will cover mutually exclusive policies a bit later, around Part 12 or 13.

“Thirteen!” cries someone in the front row. “Do we really have that many to go?”

Did I say this was simple or easy? I’m just getting warmed up.

(Groans and eye-rolling all around.)

Now that the subject of keeping track of the ICD-9 code or codes that an ICD-10 code “came from” has surfaced, let me say this: While in theory it is not strictly necessary, in practice there is no harm in keeping track of the ICD-9 codes. Many people feel more comfortable about the process when they can go back later to an ICD-10 policy and see why each code on the policy is there. Our software keeps track of these relationships as a matter of course.

In fact, using the source ICD-9 codes as tags to keep track of other information (like the Care Management program in the first question, or the payment level in the second) and converting multiple policies in one pass as the Care Management guy suggested is a convenient shortcut. But as we discuss some of the issues you may have to deal with, I’m going to assume that you are working on one policy – one list with one meaning – and that if you had multiple related policies, you separated them out ahead of time. That way, I can speak of “your ICD-9 policy” without having to issue a string of exceptions and qualifications.

This brings us back to the DIY conversion step with which we started this part of the series: you have looked up each of the ICD-9 codes on your policy in the 10-to-9 singles map with reverse index, and if the meaning of all of the ICD-9 codes were included in one or more ICD-10 codes, and the ICD-10 “replacements” were listed, you were done. But what if there were no entries in the 10-to-9 singles map with reverse index for some of your ICD-9 codes? I had you put those on an “ICD-9 orphans” list.

What are these ICD-9 orphan codes? They could be conditions that were thought to be one thing in 1974, but are now classified elsewhere. They could be making distinctions that medical practice no longer finds necessary (for example, the myriad ways tuberculosis might have been confirmed). They could be procedures introduced during the last forty years which never caught on. They could be what we call ICD-9 “combination codes.” They include two or more diagnoses or procedures that are classified as separate codes in ICD-10. Can you ignore ICD-9 orphans? Maybe. But if you want to be thorough, you have to check. In part 9, we show you how.

Ron Mills is a Software Developer for the Clinical & Economic Research department of 3M Health Information Systems.

You can find the complete DIY ICD-10 series here.