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st: RE: s: ICD9 to ICD10 converter utility?

From   "POPE, REBECCA" <[email protected]>
To   "'[email protected]'" <[email protected]>
Subject   st: RE: s: ICD9 to ICD10 converter utility?
Date   Fri, 21 Jan 2011 14:13:53 -0600

I wrote a reply to Neil's post earlier today, but 3 hrs later it still has not appeared in my inbox. I apologize if the rest of you have seen it or if it materializes later. It took an hour for Harry's to arrive based on the time stamp below, so perhaps my network is running slow today. What follows is slightly modified in light of Harry's comments.

I do not know of any such utility in Stata. However, if you are working with U.S. medical claims data, you could accomplish what you are wanting by the following:

1. Download the ICD-9-CM & ICD-10-CM crosswalk text files from the U.S. Centers for Disease Control and Prevention's National Center for Health Statistic's website (here is the link for the current versions: The relevant .zip file is *See the note below.

2. Choose the appropriate file to import. I recommend reading the PDF file supplied by the NCHS & included with the ZIP file referenced above. The data are in fixed format, so you can use -infix-. For simplicity, I recommend naming the first variable (they come without names) the same as your diagnosis code variable since this is what you'll be merging on. You can name the 2nd one whatever you like. I think the 3rd variable will be extraneous for your purpose.

3. Merge the imported file with your current data set. I don't know what version of Stata you are using, but if you need help with this, just type -help merge-.

You now have a dataset with your original diagnosis code & the alternate version (either 9 or 10). Hopefully your original codes are not a mix of 9s and 10s. If so, the process above is a bit more complex. Let me know if you need more information. 

As an aside: I am interested in working with someone to write an .ado file that could do the above and test it on multiple versions of Stata, so please let me know if you'd like to collaborate on that. I'm using version 11.1. 

*Note on ICD-9 vs ICD-9-CM (also for 10):
There is a difference between ICD-9 and ICD-9-CM. I mention the ICD-9-CM files because that's what I'm familiar with and there is a _chance_ that when you said "ICD-9" you meant "ICD-9-CM". Many of my colleagues don't specify "CM" until the publication stage even though it is the correct terminology in many cases for codes in the U.S. I'm far too often guilty myself! If you are in the U.S. & working with health insurance claims data, you are probably working with ICD-9-CM codes, which differ slightly from ICD-9 codes. 

For more information on the differences & to see if the crosswalk file above will still suit your purposes even with non-U.S. data, read and Harry might also be able to provide you with some tips. I know woefully little about how claims research is done outside the U.S. 

Prior to Harry's post, I thought everyone outside the U.S. used the World Health Organization's standard ICD-9 or 10 system. Like I said, "woefully little"... If there are large enough differences between the ICD10AM & ACHI coding systems Harry mentions and the ICD-10 standard it may be fun to develop a Stata program that could translate between systems. Does anyone think such an effort is necessary/worthwhile?


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Harry Comber
Sent: Friday, January 21, 2011 11:04 AM
To: [email protected]
Subject: st: s: ICD9 to ICD10 converter utility?

There are a number of mapping tables available from ICD9 to ICD10 (see,
for instance, but no Stata dataset of which I am aware. The zip file
contains an Excel file which can be imported into Stata. However, as
ICD10 is more extensive than ICD9, a simple one-to-one mapping is not
possible. Some of the mapping tables of these are designed to be used
with the full ICD9CM and ICD10AM (or ACHI) diagnosis and procedure
codes, but contain the diagnosis codes within this. 
Harry Comber

Dr. Harry Comber, Director
National Cancer Registry (
Building 6800
Cork Airport Business Park
Kinsale Road
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Fax +353 21 4318016
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-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Neil Shephard
Sent: Friday, January 21, 2011 4:22 PM
To: [email protected]
Subject: Re: st: ICD9 to ICD10 converter utility?

On Fri, Jan 21, 2011 at 3:05 PM, roland andersson
<[email protected]> wrote:
> Dear Statalisters
> I wonder if there is a utility for Stata that can convert IC9 to ICD10
> codes or the other way (or in other program)? It would facilitate my
> work to only have one list of disease codes.

When I asked this question a few years back someone kindly forwarded
me a copy of a Stata dataset that they use which mapped ICD9 <-->

Unfortunately I no longer have the file as it resides on the network
drives of an old employer and I can't remember who it was who sent it
to me.

Sorry thats not much help,


"Truth in science can be defined as the working hypothesis best suited
to open the way to the next better one." - Konrad Lorenz

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