As US hospitals are beginning the process of migration from ICD-9 to ICD-10, I wondered how the much larger ICD-10 dictionary might affect the diversity of coding diagnosis and surgical procedures.
Since Canada implemented ICD-10 in 2001, we can visit our neighbors to the North and see how their coding changed as they converted to the new schema.
The first step is to set up a report to check all "IN" patients for a discharge date range, in a report that has no detail region:
Then we add a computed sort field where we will group patients by the calendar year of their discharge date. The $4 takes the YYYY off of YYYYMMDD discharge date.
We select all the "IN" patients for a dis.date range:
We write a small "detail" macro to execute each record to loop on the diagnoses and operative procedures to create some temporary lists of unique diagnoses and procedures, both for the entire report range, and for each year:
This code makes a list in slash of each code, in four different globals:
/DX[dx] for all dx codes
/PROC[proc] for all procedure codes
/DXY[year,dx] for diagnoses by year
/PROCY[year,proc] for all operative procedures by year
For example, /DXY[dx] looks like this (note the leading alpha in the ICD-10 codes):
To put totals on the report, we can use a computed field to loop on the sort value in the TK region and count the number of diagnosis and procedures for the year. By using the + operator in a "DO" loop and then incrementing the variable TOT by 1 for each unique code in our list, we can count the unique codes per each year in the TK1 region.
The fields in the TR region loop on /DX[dx] and /PROC[proc] to count codes for the entire report date range.
We also create some fields to compare the 1999 patient count, unique diagnosis count, and unique procedure count to the values for each subsequent year. To do this we use a TK1 macro to loop one time thru the values for 1999 to provide a diagnosis count and procedure count that we can then use as the denominator to calculate some percentages.
The macro looks like this:
Since ICD-9 has 13,000 diagnosis codes and ICD-10 has about 68,000, and ICD-9 has 3,000 procedure codes and ICD-10 has about 87,000 codes, we would expect to see more unique codes after the transition from ICD-9 to ICD-10.
In a completely non-scientific survey of two Canadian sites, we see only a slight increase in the diversity of codes between 1999 and >2001. Here is the first hospital:
Here is a second hospital:
A sample (MAGIC) report ABS.PAT.zcus.is.icd9 has been uploaded to our report library. Code for a Client/Server version would be identical.