Cheat sheet basics for ICD-10

With this, my 9th post in the "ICD-10 Essentials for Busy Physicians Who Would Rather Be Doing Something Else" series, I could get all high and mighty and wag my finger at those who have no intention of doing any of that “good for you” stuff the industry has been recommending. Things like taking advantage of ICD-10 specificity, modernizing and upgrading your office systems, yada yada yada.

It is no doubt a good idea and it may very well benefit you in ways you can’t anticipate (aside from avoiding penalties and maybe even getting in on a little incentive money). But I am practically allergic to telling people what to do. So, if you want to stick with this cheat sheet for coding in ICD-10, I will not try to talk you out of it.

Popular hype says it is impossible to make a reasonable-sized coding cheat sheet that contains the most common conditions coded in your practice. For many of you, that is emphatically not so. Gastroenterologists have 596 ICD-9 codes and 706 codes in ICD-10; pulmonologists have 255 codes in ICD-9 and 336 codes in ICD-10; urologists have 389 codes in ICD-9 and 591 codes in ICD-10; endocrinologists have 335 codes in ICD-9 and 675 codes in ICD-10; neurologists have 459 codes in ICD-9 and 591 codes in ICD-10; pediatricians have 702 codes in ICD-9 and 591 codes in ICD-10. The infectious disease specialists actually lost codes, from 1,270 in ICD-9 down to 1,056 in ICD-10. (I expect to hear howls of protest -- not really.)

For some of the rest of you -- orthopedists and OB/GYN docs and oncologists -- the numbers go up significantly. Let’s call it an “interesting challenge” and take a look at how it can be done.

I am going to only touch on a couple of principles of cheat sheet building for ICD-10. To do this, I am going to use examples from the musculoskeletal system and injury chapters. Aside from the ER docs, who typically don’t do their own coding anyway, the orthopedists have the biggest challenge in cheat sheet building. The increase in number of codes is concentrated in the musculoskeletal system and injury chapters mainly because additional anatomic site and encounter detail is applied there across the whole chapter.

Principle 1: Apply the 80/20 rule
In the world of ICD-9, you were probably able to make a cheat sheet that covered 95 percent of the stuff you see in your practice. Make your coverage goal for ICD-10 more modest. The rarer conditions could well double the size of your cheat sheet and defeat the whole purpose -- making coding for your practice easier and more efficient. For example, many diagnoses pertaining to the joints in ICD-9 did not name the joint in the code. In ICD-10 the joint is specified, along with whether it is the right or left where such things apply. So, one code on your cheat sheet under the old system becomes lots of codes in the new.

For example, Felty’s syndrome is one code in ICD-9 and 23 codes in ICD-10. Since Felty’s syndrome is relatively rare, you could probably leave it off your cheat sheet. For conditions you want on your cheat sheet, like osteoarthritis and rheumatoid arthritis, apply the 80/20 rule to anatomic site, and include only codes for sites you see most commonly, like hips, hands, etc.

Principle 2: Take advantage of recurring code patterns
The developers of ICD-10-CM tried to apply a new axis of classification consistently, having the same letter or number in the same position mean the same thing. This is especially evident in the injury chapter. Seventh character extensions for all injury codes specify an initial encounter for injury, a subsequent visit for aftercare, or a visit to treat a late effect of the injury.

Seventh character extensions are a lot like “required modifiers” that have been automatically applied to the codes. It is much more efficient to list seventh character extensions separately on the portion of your cheat sheet where they apply, with the applicable code range where they are to be used. They are listed separately in the ICD-10-CM book and it saves a lot of space when done this way:

The appropriate 7th character is to be added to each code from category S01
A - initial encounter
D - subsequent encounter
S - sequela

For many of the fracture codes, including pathologic fractures, there are even more detailed seventh character extensions. For example, here are extensions for fractures at the wrist and hand level.

The appropriate 7th character is to be added to each code from category S62

A - initial encounter for closed fracture
B - initial encounter for open fracture
D - subsequent encounter for fracture with routine healing
G - subsequent encounter for fracture with delayed healing
K - subsequent encounter for fracture with nonunion
P - subsequent encounter for fracture with malunion
S – sequela

By simply formatting these “modifiers” as presented in the book, you can reduce the number of wrist and hand fracture codes on your cheat sheet by a factor of six.

And you can go even further. For example, where specific codes exist for left, right and unspecified, they will be the same across a broad area. You could list this as a modifier, like so:

For the final character of codes in range M00-M65
Right = 1
Left = 2
Unspecified = 9

I will be the first one to admit I have oversimplified both the problem and the solution. Blogs are not famous for being subtle or detailed. But hopefully these two ideas will help you better understand the way the system is structured, and if you intend to continue using cheat sheets you can use them to make one that is as efficiently represented and easy to use as it can be.

Rhonda Butler is a senior clinical research analyst with 3M Health Information Systems. She is responsible for the development and maintenance of the ICD-10 Procedure Coding System since 2003 under contract to CMS, and for the development and maintenance of the ICD-10 General Equivalence Mappings (GEMs) and Reimbursement Mappings under contract to CMS and the CDC.  She leads the 3M test project to convert the MS-DRGs to ICD-10 for CMS, and is on the team to convert 3M APR-DRGs to ICD-10. Rhonda also writes for the 3M Health Information Systems blog.