Important Coding Update: Bipolar I Versus Bipolar II

When assigning for behavioral health, coders note the difference in the codes for bipolar disorder type I and bipolar disorder type II, but often wonder: what is the difference between them? While they are both are considered to be mood disorders, there are some differences we will examine here. 

First, according to World Health Organization (WHO) data from 2019, bipolar disorder affects around 40 million people. The data further notes that men and women are affected by bipolar disorder equally. It is one of the leading causes of disability globally, and on average, people who have bipolar disorder die 10 years earlier than the general population. 

When we think of bipolar disorder, we may think about a person who has a really high mood at times and a really low mood at other times. These extreme mood swings are characteristic for this condition. The high moods indicate the so-called “manic” phase of bipolar. The patient may feel very happy, have lots of energy, and may not sleep as they normally would.

During this phase the patient may move from one thing to the next, with difficulty concentrating. They may also be more restless or irritable than usual. 

In the “depressive” phase of the disorder, the patient may also have difficulty concentrating and may experience a change in their sleep pattern. In this phase, however, as the name suggests, the patient will feel sadness: they don’t enjoy things as they did before. They may feel tired, have no energy, feel hopeless, and may even have suicidal thoughts. 

In the Alphabetic Index, we note an entry for “hypomanic.” While a hypomanic phase is similar to a manic phase, the symptoms are not as intense, which allows the patient to be able to function more normally. We would assign F31.0 for Bipolar disorder, current episode, hypomanic.

When we are assigning for bipolar disorder, starting at our Alphabetic Index with Disorder, bipolar, we see that type I is a non-essential modifier. Bipolar disorder type II has a separate entry. So, back to our original question: what is the difference?

According to the WHO, patients with bipolar type I have had one or more manic episodes with episodes of depression. Over time, the depressive episodes become more common. Patients with bipolar disorder type II have had one or more of the hypomanic type episodes and at least one depressive episode. Patients with bipolar type II have no history of a manic episode.

Bipolar type I codes identify the current episode (manic, depressed, or mixed), identify if psychotic features are present, and identify the severity, if psychotic features are not present. If psychotic features are identified, it is included and assigned as severe with psychotic features. Bipolar with manic episode would be assigned to F31.10-F31.2. Bipolar with depressed episode would be assigned to F31.30-F31.5. Mixed bipolar episodes would be assigned to F31.60-F31.64. Category F31.7 classifies cases currently in remission, identifying by the most recent episode. 

We have one code for bipolar disorder type II, F31.81. As with many of our other disease and disorder codes, we also have an option for “other” and an unspecified option. Bipolar disorder groups to MS-DRG 885, Psychoses. There is an Excludes 1 note at F31 Bipolar Disorder for both single-episode and recurrent major depressive disorder.

We also have Coding Clinic guidance from the first quarter of 2020 instructing that bipolar disorder includes both depression and mania, and it is more important to capture the bipolar disorder code when both conditions are documented.

It is important for us as coders to have a good understanding of diseases and conditions, in order to ensure we are assigning as completely and correctly as possible.

Programming note:

Listen every Tuesday when Christine Geiger reports the latest coding news and information on Talk Ten Tuesday with Chuck Buck and Angela Comfort, 10 Eastern.