Section 2: How to Use GEM Files

Section 2—How to Use GEM Files

For ease of use, we recommend loading the GEM files into a database along with the code descriptions for both code sets. With roughly 85,000 codes and their descriptions in both code sets, a desktop database like MS Access is adequate.

A general process for using the GEMs consists of three basic steps. In most cases it is expected these steps will be performed by software designed to integrate the GEMs content and translate codes or lists of codes from I-9 to I-10 or vice versa. In that case that a small number of records need to be translated, and the user has access to the original medical record, it is more efficient and accurate to look the codes up directly in the respective ICD-9-CM or ICD-10-CM book.

The code we will use for purposes of demonstration is I-9 code 599.72, Microscopic hematuria.

I-9 to I-10 GEM:
599.72 Microscopic hematuria

The illustrations at left and below display the I-9 code 599.72 as it appears in the I-9 to I-10 GEM. At left is the entry in text file format with its adjacent GEM entries, and below is the same information as it would appear in a desktop database. Note that the codes do not contain decimals in the GEMs.

59972 R311 10000 59972 R312 10000 59981 N3641 00000 59982 N3642 00000 59983 N368 10000 59984 N368 00000 59989 N398 00000 5999 N369 10000 5999 N399 10000

The code in the source system is listed first, followed by the code in the target system. Here the source system is the I-9 code and the target system is the I-10 code. The final group of digits is used to indicate additional attributes for entries in the map. The first three digits are called flags. The last two digits are used in combination entries, and will be discussed later. The GEM entry contains a flag characterizing the degree of correspondence between codes in one row (“approximate” flag), a flag for codes with no correspondence in the target system (“no map” flag) and a flag indicating the row is part of a combination entry (“combination” flag). If the digit is 1, the flag applies (is “turned on”) to that entry in the GEM. If the digit is 0, the flag does not apply (is “turned off”) to that entry in the GEM. In other words, 1 means “yes,” the flag applies to the entry in a GEM and 0 means, “no,” the flag does not apply. There are two rows in the I-9 to I-10 GEM for code 599.72. The entry is of the single type, meaning that each row—code 599.72 linked to one of two I-10 code alternatives—is considered a valid entry.

I-9 Code	I-9 Description	I-10 Code	I-10 Description	Approximate [FLAG]	No Map [FLAG]	Combination [FLAG]
599.72	Microscopic hematuria	R31.1	Benign essential microscopic hematuria	1	0	0
599.72	Microscopic hematuria	R31.2	Other microscopic hematuria	1	0	0

Step 2: ANALYZE

Is the “approximate” flag turned on? If yes, the correspondence is not a precise equivalent. Is the “no map” flag turned on? If yes, there is no corresponding code in the target system. Is the “combination” flag turned on? If yes, more than one code is the target system is required to satisfy the meaning of the code in the source system.

In the GEMs, there are three flags:

Approximate	indicates that the entry is not considered equivalent
No Map	indicates that a code in the source system is not linked to any code in the target system
Combination	indicates that more than one code in the target system is required to satisfy the full equivalent meaning of a code in the source system

The Approximate Flag

I-9 Code	I-9 Description	I-10 Code	I-10 Description	Approximate [FLAG]	No Map [FLAG]	Combination [FLAG]
599.72	Microscopic hematuria	R31.1	Benign essential microscopic hematuria	1	0	0
599.72	Microscopic hematuria	R31.2	Other microscopic hematuria	1	0	0

The approximate flag is turned on when no one code in the target system or linked combination of codes in the target system expresses the same essential meaning as the code in the source system. The difference between the two systems is typically in level of detail between the codes, and in nearly all cases the I-10 code is more detailed than the I-9 code.

The approximate flag is on for both rows in the source system GEM entry for I-9 code 599.72. The level of detail differs here—the type of hematuria is specified in I-10 and not in I-9. Although 599.72 Microscopic hematuria in I-9 and R31.2 Other microscopic hematuria in I-10 could be said to be equal, in fact they are not, because the I-9 code represents all varieties of microscopic hematuria and the I-10 code represents only microscopic hematuria not classified in the other code. The approximate flag is turned on to indicate no single code in I-10 expresses the same meaning as 599.72.

The approximate flag is on for the majority of entries in the GEMs. This may include code pairs that have the same description in both code sets. In such cases, neighboring codes in a subcategory are more specific in one code set than another, and so the number of clinical conditions included in a code is different—hence it does not express the same essential meaning. Codes containing the word “other” in their description are a common example.

I-10 Code	I-10 Description	I-9 Code	I-9 Description	Approximate [FLAG]	No Map [FLAG]	Combination [FLAG]
B37.41	Candidal cystitis and urethritis	112.2	Candidiasis of other urogenital sites	1	0	0
B37.42	Candidal balanitis	112.2	Candidiasis of other urogenital sites	1	0	0
B37.49	Other urogenital candidiasis	112.2	Candidiasis of other urogenital sites	1	0	0

In this example, the body sites included in the “other candidiasis” code differs between code sets, so the approximate flag is on for all entries in this subcategory. I-10 has specific codes for cystitis/urethritis and balanitis. I-9 does not. In I-9, balanitis is listed as an “includes” note under the code 112.2 Candidiasis of other urogenital sites, and cystitis or urethritis have no specific entry in tabular.

The No Map Flag

I-9 Code	I-9 Description	I-10 Code	I-10 Description	Approximate [FLAG]	No Map [FLAG]	Combination [FLAG]
V64.41	Laparoscopic surgical procedure converted to open procedure	NoDx	No Description	0	1	0
V64.42	Thoracoscopic surgical procedure converted to open procedure	NoDx	No Description	0	1	0
V64.43	Arthroscopic surgical procedure converted to open procedure	NoDx	No Description	0	1	0

In the I-9 to I-10 GEM, the “no map” flag is on for a subset of I-9 codes. In this example, the I-9 codes do not identify a diagnosis, but instead further specify the reason why a procedure was performed differently than planned. The recommendation was made that I-10 diagnosis codes do not contain information regarding procedures, so I-10 does not contain an equivalent group of codes. Therefore, the I-9 codes cannot be linked to I-10 at all. In the I-9 to I-10 GEM they are listed without a corresponding I-10 entry, and with the “no map” flag on.

The Combination Flag

The combination flag is turned on when a code in the source system must be linked to more than one code in the target system to be a valid entry. When the combination flag is on, the scenario and choice list fields in a GEM file contain a number. They appear last in a GEM file, after the flags. These numbers allow the user to collate the combination entries in the GEM.

T422X1A 9662 10111 T422X1A E8558 10112 T422X1A 9660 10121 T422X1A E8558 10122 T422X1D V5889 10000 T422X1S 9090 10111 T422X1S E9292 10112 T422X2A 9662 10111 T422X2A E9504 10112 T422X2A 9660 10121 T422X2A E9504 10122 T422X2D V5889 10000 T422X2S 9090 10111 T422X2S E959 10112

I-10 to I-9 GEM:
T42.2X1A Poisoning by succinimides and oxazolidinediones, accidental (unintentional),initial encounter

The illustrations at left and below display the I-10 to I-9 GEM entry for I-10 diagnosis code T42.2X1A Poisoning by succinimides and oxazolidinediones, accidental (unintentional), initial encounter. At left is the entry in text file format, and below is the same information as it would appear in a desktop database. The I-10 combination code T42.2X1A specifies both the diagnosis and the external cause, so it requires a combination entry in the GEM. A combination entry is subdivided hierarchically on two levels: 1) By scenario, the number of variations of diagnosis combinations included in the source system code, and 2) By choice list, the possible target system codes that combined are one valid expression of a scenario.

Each of the two types of drug listed in the I-10 code T42.2X1A is a unique I-9 code, so there are two scenarios from which to choose an applied mapping: one that specifies poisoning by succinimides and one that specifies poisoning by oxazolidinediones. Because each drug type listed in the I-10 combination code requires its own diagnosis code in I-9, each variation of the diagnosis is assigned a separate scenario number in the GEM entry.

A scenario designates one variation of the meaning of the source system diagnosis as specified in a combination code. In other words, it identifies one roughly equivalent expression of the source system code. In this example, scenario 1 contains the I-9 codes needed to satisfy the equivalent meaning of “Poisoning by succinimides, accidental (unintentional), initial encounter” Scenario 2 contains all the I-9 codes needed to specify “Poisoning by oxazolidinediones, accidental (unintentional), initial encounter.”

A scenario is subdivided into two or more choice lists of codes in the target system. These are the codes that must be linked together as a unit in an applied mapping to satisfy the equivalent meaning of the combination code in the source system. A choice list contains one or more codes in the target system that express a portion of the meaning of the code in the source system. A code must be included from each choice list in a scenario to satisfy the equivalent meaning of the code in the source system.

Scenario 1

I-10 Code	I-10 Description	I-9 Code	I-9 Description	Approximate [FLAG]	Combination [FLAG]	Scenario	Choice list
T42.2X1A	Poisoning by succinimides and oxazolidinediones, accidental (unintentional), initial encounter	966.2	Poisoning by succinimides	1	1	1	1
T42.2X1A	Poisoning by succinimides and oxazolidinediones, accidental (unintentional), initial encounter	E855.8	Other specified drugs acting on central and autonomic nervous systems	1	1	1	2

Scenario 2

I-10 Code	I-10 Description	I-9 Code	I-9 Description	Approximate [FLAG]	Combination [FLAG]	Scenario	Choice list
T42.2X1A	Poisoning by succinimides and oxazolidinediones, accidental (unintentional), initial encounter	966.0	Poisoning by oxazolidine derivatives	1	1	2	1
T42.2X1A	Poisoning by succinimides and oxazolidinediones, accidental (unintentional), initial encounter	E855.8	Other specified drugs acting on central and autonomic nervous systems	1	1	2	2

In this example there are two I-9 choice lists in scenario 1 and two I-9 choice lists in scenario 2, with one I-9 code in each list.

This is a comparatively simple example of a combination entry because each choice list contains only one code. The user does not need to choose among alternatives beyond the scenario.

The result is that for this I-10 combination entry, there are only two applied mapping alternatives:

Scenario 1

ICD-10-CM Source	to	ICD-9-CM Target
T42.2X1A Poisoning by succinimides and oxazolidinediones, accidental (unintentional), initial encounter	≈	966.2 Poisoning by succinimides AND E855.8 Other specified drugs acting on central and autonomic nervous systems

OR


Scenario 2

ICD-10-CM Source	to	ICD-9-CM Target
T42.2X1A Poisoning by succinimides and oxazolidinediones, accidental (unintentional), initial encounter	≈	966.0 Poisoning by oxazolidine derivatives AND E855.8 Other specified drugs acting on central and autonomic nervous systems