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How to Identify and Apply ICD-10 Combination Codes to Improve Medicare Risk Adjustment Performance in 2019 and Beyond

binary codes laid out vertically in stalagmite formation
September 9, 2019

There’s no doubt Medicare Advantage (MA) plans and other risk-bearing entities have heard about ICD-10 combination codes, but with the increased amount of single ICD-10 codes over the past few years, it’s crucial to understand why and how to assign them. Since ICD-10 combination codes play a significant role in coding and risk adjustment, they’re key to closing hierarchical condition category (HCC) gaps, receiving reimbursement in a timely manner, and reducing costs.

But what are combination codes? And how do you sift through the increasing amount of new ICD-10 combination codes, HCC codes, and coding clinics released each year to implement the changes concurrently and retrospectively? We have answers to your questions below.

What are ICD-10 Combination Codes?

ICD-10 combination codes allow you to report a single code which includes multiple characteristics of the diagnosis.

According to the ICD-10-CM Official Guidelines for Coding and Reporting FY 2019, a combination code is a single code used to classify:

  • Two diagnoses
  • A diagnosis with an associated secondary process (manifestation)
  • A diagnosis with an associated complication

In 2019, there were 279 new codes, 143 revised codes, and 51 deleted codes released by CMS and the National Center for Health Statistics (NCHS).

Rather than assigning multiple diagnostic codes, it’s recommended to use single combination codes to accurately represent the patient’s condition and receive the higher RAF value. Since RAF scores for patients who are assigned ICD-10 combination codes can be as much as five times the amount of risk adjustment factor (RAF) and the associated bump in reimbursement, it’s crucial to use the appropriate combination codes to accurately represent patients’ conditions.

Here are two examples of combination codes and how they can affect RAF scores.

Example #1: Vascular Disease

HCC 106 – Atherosclerosis of the Extremities with Ulceration or Gangrene (RAF value 1.588)


HCC 108 – Vascular Disease (RAF value .327)

Codes that represent vascular disease, mapped to HCC 108.

I70.201 Unspecified atherosclerosis of native arteries of extremities, right leg

I70.202 — left leg

I70.203 — bilateral legs

I70.208 — other extremity

I70.209 — unspecified extremity

I70.211 Atherosclerosis of native arteries of extremities with intermittent claudication, right leg

I70.212 — left leg

I70.213 — bilateral legs

I70.218 — other extremity

I70.219 — unspecified extremity

I70.221 Atherosclerosis of native arteries of extremities with rest pain, right leg

I70.222 — left leg

I70.223 — bilateral legs

I70.228 — other extremity

I70.229 — unspecified extremity

If an ulcer develops due to atherosclerosis, the following combination codes are used. As you can see, the combination codes represent both the underlying cause (atherosclerosis) and the manifestation (ulceration). The following codes yield HCC 106:

I70.231 Atherosclerosis of native arteries of right leg with ulceration of thigh

I70.232 — of calf

I70.233 — of ankle

I70.234 — of heel and midfoot

I70.235 — of other part of foot

I70.236 — of other part of lower right leg

I70.239 — of unspecified site


If a coder does not use a combo code and simply codes Vascular Disease from HCC 108 and an ulcer from the L-codes, you will not get the higher RAF value for HCC 106. These combination codes must be used specifically.

Example #2: Substance Abuse / Psychosis

HCC 54 – Substance Use with Psychotic Complications (RAF value 0.564)


HCC 55 – Substance Use Disorder, Moderate/Severe, or Substance Use with Complications (RAF value 0.283)

HCC 54 is worth approximately double the RAF score of HCC 55.

Codes that represent substance use disorder, mapped to HCC 55:

F10.120 Alcohol abuse with intoxication, uncomplicated

F10.121 Alcohol abuse with intoxication delirium

F10.129 Alcohol abuse with intoxication, unspecified

Codes mapped to HCC 54:

F10.150 Alcohol abuse with alcohol-induced psychotic disorder with delusions

F10.151 Alcohol abuse with alcohol-induced psychotic disorder with hallucinations

F10.159 Alcohol abuse with alcohol-induced psychotic disorder, unspecified


If single codes for “alcohol abuse unspecified,” “delusions,” “hallucinations,” or “unspecified psychosis,” are used individually, it will not trigger the more valuable HCC and subsequent reimbursement.

Clinical Value

Accurately identifying and applying combination codes can also trigger disease management programs, which can help educate members about their conditions and provide interventions that prevent higher costs associated with caring for a riskier member. Diet and exercise counseling, enrollment in support groups, assistance in scheduling specialist appointments to treat specific issues, transportation assistance to medical appointments, and enrollment in a Silver Sneakers or a similar exercise program are all examples of these kinds of programs and interventions. When successful, they can prevent complications from progressing unchecked and save millions of dollars in hospital care.

Best Practices for a Complicated Process

ICD-10 coding is challenging in itself, but with combination codes specifically, there are several guidelines and standards regarding which codes can be used — and which cannot — as well as quarterly updates from the American Hospital Association’s Coding Clinic that provide detailed instructions on how to properly apply the codes. When it comes to providers, some aren’t aware that combination codes exist and for those who do, they simply don’t have the time to search for and identify the right ones. Therefore, implementing the changes concurrently and retrospectively is a complicated, challenging process.

Have a Coding Expert

Since the new ICD-10 codes and the HCCs are released once a year, and the coding clinics are released quarterly, it’s important to have one or more experts on staff who specifically deal with risk-adjusted ICD diagnostic coding. These subject matter experts should understand how to execute retrospective projects that take into account the new codes and the corresponding risk adjustment model.

Evaluate Records

You also need to use coders and/or an NLP-enabled software to identify which records to review to identify the ICD-10 combination codes. Then you can determine whether or not those combination codes have been applied.

Provide Ongoing Education for Providers

Since identifying and applying the ICD-10 combination codes is crucial for reimbursement, you should educate your providers on how to secure them right at the source. Providers should consistently be informed about the combination codes and updates, as well as how to properly document and assign the codes.

Utilizing a provider query can help you identify areas in which a provider’s documentation tends to be weak or confusing. Since providers are busy caring for patients, you should focus on — and customize —  education for your providers. It’s always more effective to be able to present a copy of the provider’s own documentation as an opportunity for improvement, instead of focusing on abstract suggestions.

For overburdened payers and providers, Episource helps close gaps in healthcare by marrying expert guidance with an end-to-end risk adjustment platform. Learn more about our solutions at Episource.com.