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ICD-10-CM 2027 diagnosis code

E66.2Morbid (severe) obesity with alveolar hypoventilation

✓ Billable / specificCC — complication/comorbidity

E66.2 is a valid, billable ICD-10-CM code for morbid (severe) obesity with alveolar hypoventilation. It can be reported on claims for dates of service from October 1, 2026 – September 30, 2027.

Looking up by condition? See ICD-10 code for OHS, ICD-10 code for Pickwickian syndrome.

Code unchanged since ICD-10-CM took effect on October 1, 2015. Source: official FY2027 ICD-10-CM release from CDC/NCHS and CMS. Page updated September 29, 2026. About our data

About E66.2

E66.2 is the ICD-10-CM diagnosis code for Morbid (severe) obesity with alveolar hypoventilation. It belongs to category E66 (Overweight and obesity), block E65-E68 (Overweight, obesity and other hyperalimentation) and chapter 4 (endocrine, nutritional and metabolic diseases). It is billable, so it can be reported on its own for dates of service from October 1, 2026 through September 30, 2027.

Within E66 (Overweight and obesity), E66.2 is specifically for Morbid (severe) obesity with alveolar hypoventilation. Related codes cover obesity due to excess calories (E66.0), drug-induced obesity (E66.1), Overweight (E66.3), other obesity (E66.8) and obesity, unspecified (E66.9).

Code first: obesity complicating pregnancy, childbirth and the puerperium, if applicable (O99.21-).

Use an additional code to identify body mass index (BMI), if known, for adults (Z68.1-Z68.45) or pediatrics (Z68.5-).

As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.

In MS-DRG v44.0, it is part of the grouping logic for DRG 205 (Other Respiratory System Diagnoses with MCC, relative weight 1.8244) and DRG 206 (Other Respiratory System Diagnoses without MCC, relative weight 0.9257), in MDC 04 (Diseases and Disorders of the Respiratory System), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.

It has been part of ICD-10-CM since the code set took effect on October 1, 2015 and hasn't changed since.

Before ICD-10, this condition was coded in ICD-9-CM as 278.03 (obesity hypoventilation syndrome).

Coding notes

Applicable toConditions and synonyms classified to this code
  • Obesity hypoventilation syndrome (OHS)
  • Pickwickian syndrome

Notes that apply from higher levels

Instructions written at a parent level also apply to E66.2.

› From E66 Overweight and obesity
Excludes2
  • adiposogenital dystrophy (E23.6)
  • lipomatosis dolorosa [Dercum] (E88.2)
  • lipomatosis NOS (E88.2)
  • Prader-Willi syndrome (Q87.11)
Code first
  • obesity complicating pregnancy, childbirth and the puerperium, if applicable (O99.21-)
Use additional code
  • code to identify body mass index (BMI), if known, for adults (Z68.1-Z68.45) or pediatrics (Z68.5-)

Broader instructions also apply from Chapter 4: Endocrine, nutritional and metabolic diseases.

Alphabetic index entries

11 entries

Terms in the official ICD-10-CM index that lead to E66.2.

Codes whose notes reference E66.2

MS-DRG v44.0 grouping

All DRGs →

Inpatient MS-DRGs this diagnosis can group to, as the principal or a secondary diagnosis, depending on the rest of the claim.

ICD-9-CM equivalent

Converter →
  • 278.03Obesity hypoventilation syndromeexact

From the CMS 2018 General Equivalence Mappings (GEMs), the final GEMs release.

Code history

  1. 2016
  2. 2017
  3. 2018
  4. 2019
  5. 2020
  6. 2021
  7. 2022
  8. 2023
  9. 2024
  10. 2025
  11. 2026
  12. 2027
  • FY2016 (effective 10/1/2015): Added (first year of ICD-10-CM)
  • No changes since FY2016.

Common questions about E66.2

Is E66.2 billable?

Yes. E66.2 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).

Can E66.2 be used as a principal diagnosis?

Yes. The Medicare Code Editor doesn't restrict E66.2 as a principal diagnosis.

Is E66.2 a CC or MCC?

E66.2 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.

What DRG does E66.2 group to?

E66.2 is used in the MS-DRG v44.0 logic for MS-DRG 205 (Other Respiratory System Diagnoses with MCC) and MS-DRG 206 (Other Respiratory System Diagnoses without MCC). Which one applies depends on whether it is the principal diagnosis and on the rest of the claim.

What is the ICD-9 code for E66.2?

The CMS General Equivalence Mappings map E66.2 to ICD-9-CM 278.03.