80-20 coding for ICD-10

I am going to be brief about the recent HHS announcement to delay ICD-10 implementation. Fighting ICD-10 implementation is roughly as old as ICD-10, and the AMA and MGMA won this round.  I only hope that whatever comes down the regulation pike, they will get some benefit that was worth the political capital spent on delaying ICD-10. 

If an “unfunded mandate” becomes an “unfunded mandate delayed for two years,” whatever it is about ICD-10 that seems intolerable will still be there waiting. So let’s make use of whatever time we have. I will continue to share what I know about ICD-10 in the hope that it will make the transition easier for physicians.

As with just about every endeavor, the 80/20 rule can be applied to learning ICD-10 terminology for the needs of your practice. Your practice spends 80 percent of its time on the most common types of patients treated in your area of specialty. The remaining 20 percent include a variety of the less common and more complex cases. The latter cannot be handled as efficiently -- in care and treatment or in coding. You deal with them as they come up.

Although each patient is unique, ICD-10’s purpose as a statistical classification is to summarize -- to lessen uniqueness so that patients can be quantified and analyzed based on shared characteristics. Just as with ICD-9, in ICD-10 similar patient encounters are coded using the same codes over and over. I can promise that, just as with ICD-9, you will end up using a very small subset of ICD-10 for the 80 percent that is the backbone of your practice. That small subset of ICD-10 is where I am going to focus. 

In this blog I am going to talk about a condition that shows up in a significant percentage of those who seek care: hypertension.

Subsequent blogs will talk about diabetes, congestive heart failure, asthma and other common chronic conditions.

Initially I am going to spend more time on coding and classification than you really need to know, only because I want to underscore the point that can’t be heard above the din of hysteria and misinformation: For the most part ICD-10 coding and documentation challenges for physician offices rarely differ in any dramatic way. When they do differ, they have often been made easier and better. I intend to cover more ground in subsequent blogs once I have made this point.

There are 88 codes in ICD-9 that use the word “hypertension” somewhere in the definition of a code, including ocular hypertension, portal hypertension and gestational hypertension. Most of these 88 are very specific conditions unrelated to what is commonly referred to as hypertension.

Only one of these ICD-9 hypertension codes is used with any frequency, for patients who are on prescribed medication to manage their condition. It is the one every coder memorizes, 401.9 Unspecified essential hypertension. Its sister code in ICD-10 is the easiest one to memorize in the whole book. It is I10 Essential (primary) hypertension.  A diagnosis of hypertension on the patient encounter can be coded to this ICD-10 code without any additional documentation.

You may have noticed that the word unspecified in the ICD-9 code has been taken out of ICD-10. ICD-9 had in it a bunch of codes (24 codes, if you want to know) that should never have been there in the first place, all because of a mistaken understanding of the term malignant hypertension. This term has long been replaced by the preferred terms hypertensive emergency or hypertensive crisis. Malignant hypertension/ hypertensive emergency refers not to a chronic condition at all, but an acute, severe rise in blood pressure that must be quickly and aggressively lowered or catastrophic organ damage may result.

A whole axis of classification was added to ICD-9 specifying whether all the types of chronic hypertensive disease were benign, malignant or unspecified. The term benign hypertension was just made up as the opposite of malignant, and malignant hypertension meant something completely different than doctors even meant back then. Go figure.

There are no separate codes for malignant (and benign) hypertension codes in ICD-10. What was unnecessarily complex and confusing has been simplified. Unnecessary queries about malignant and benign hypertension will cease.

For patients who are on maintenance medication for hypertension, but don’t have hypertensive heart or kidney disease, three codes have been replaced by one.

I10 Essential (primary) hypertension replaces:

401.0 Malignant essential hypertension 
401.1 Benign essential hypertension 
401.9 Unspecified essential hypertension

In my next blog, I will focus on ICD-10 80/20 coding and documentation information for two more common chronic conditions: CHF and diabetes.

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.


Comments (1)

Georgia L Newman MD FACP: I love this blog. As a weirdo physician who has coded for years and actually has a tabbed and pasted on ICD-9 book, I have been curious about ICD-10. I will probably be the physician to help the other (clueless) ones with ICD-10. I don't see much clinical activity anywhere dealing with the conversion. Everyone I know is just quietly hoping that it will go away, and the delay just reinforced that notion.

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