2027 ICD-10-CM Diagnosis Code D81.9Combined immunodeficiency, unspecified
ICD-10-CM Codes›D50–D89›D80-D89›D81
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 114
- Chronic Condition
D81.9 is a billable ICD-10-CM diagnosis code for combined immunodeficiency, unspecified. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 808 through 810. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 44 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Immunity disorders.
For Medicare Advantage risk adjustment, D81.9 maps to CMS-HCC Category 114 (Common Variable and Combined Immunodeficiencies) under the V28 model, adding a risk factor of about 2.262 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
D81.9 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2027.
Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Autoimmune hemolytic anemia, autoimmune thrombocytopenia, primary immunodeficiency syndrome
- Autosomal recessive SCID
- Benign combined immunodeficiency
- Combined immunodeficiency disease
- Combined immunodeficiency with faciooculoskeletal anomalies syndrome
- Combined immunodeficiency with granulomatosis
- Congenital atrophy of optic nerve
- Hepatic veno-occlusive disease with immunodeficiency syndrome
- Obstruction of visceral vein
- Severe combined immunodeficiency disease
- Severe combined immunodeficiency with low T- and B-cell numbers
- Severe combined immunodeficiency with maternofetal engraftment
- Severe combined immunodeficiency, microcephaly, growth retardation, sensitivity to ionizing radiation syndrome
- Short-limb skeletal dysplasia with severe combined immunodeficiency
- Veno-occlusive disease of the liver
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to D81.9: its own notes plus those printed at D81, block D80-D89, and Chapter 3. A note printed at a category, block or chapter applies to every code under it.
Includes
Further defines, or gives examples of, the content of the category.
- defects in the complement system
- immunodeficiency disorders, except human immunodeficiency virus [HIV] disease
- sarcoidosis
Applicable To
Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.
- Severe combined immunodeficiency disorder [SCID] NOS
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- autosomal recessive agammaglobulinemia (Swiss type) (D80.0)
Excludes2
Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.
- human immunodeficiency virus [HIV] disease (B20)
- autoimmune disease (systemic) NOS (M35.9)
- certain conditions originating in the perinatal period (P00-P96)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- human immunodeficiency virus [HIV] disease (B20)
- injury, poisoning and certain other consequences of external causes (S00-T88)
- neoplasms (C00-D49)
- symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Referenced in Other NotesGuidance
Instructional notes printed at other codes that name D81.9, its category, or a range that includes it.
Excludes1 3
These codes carry an Excludes1 note naming D81.9: they are not reported together with it, unless the two conditions are unrelated.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
combined D81.9
severe (SCID) D81.9
severe combined (SCID) D81.9
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Immune System and Disorders
Your immune system is a complex network of cells, tissues, and organs. Together they help the body fight infections and other diseases.
The full article covers:
- What is the immune system?
- What are the parts of the immune system?
- How does the immune system work?
- What are the types of immunity?
- What can go wrong with the immune system?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert D81.9 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About D81.9Overview
What is the ICD-10 code for combined immunodeficiency, unspecified?
The ICD-10-CM code for combined immunodeficiency, unspecified is D81.9 (sometimes written as D819). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is D81.9 (Combined immunodeficiencies) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report combined immunodeficiency, unspecified on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does D81.9 group to?
When combined immunodeficiency, unspecified is the principal diagnosis on an inpatient stay, it groups to MS-DRG 808, 809, 810, with relative weights from 1.0749 to 2.1706 depending on complications. Higher weights mean higher Medicare reimbursement.
Is D81.9 a CC or MCC?
CMS lists D81.9 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 44 closely related codes in its exclusion list.
Can D81.9 be reported with D80.0?
Not as a rule. The Excludes1 note at D81, which applies to D81.9, lists "autosomal recessive agammaglobulinemia (Swiss type) (D80.0)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).
What HCC is D81.9?
D81.9 (combined immunodeficiency, unspecified) maps to CMS-HCC Category 114 (Common Variable and Combined Immunodeficiencies), commonly written as HCC 114, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 47 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 99.
Does D81.9 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, D81.9 adds a risk adjustment factor of about 2.262 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.691 to 2.789 depending on the payment segment). HCC 114 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 114 category page.
