2027 ICD-10-CM Diagnosis Code M06.4Inflammatory polyarthropathy
ICD-10-CM Codes›M00–M99›M05-M14›M06
- Billable — Valid for Submission
- Risk Adjusts — HCC 94
- Chronic Condition
M06.4 is a billable ICD-10-CM diagnosis code for inflammatory polyarthropathy. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 553 through 554. Coders also document this condition as autoimmune leukopenia. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Rheumatoid arthritis and related disease.
For Medicare Advantage risk adjustment, M06.4 maps to CMS-HCC Category 94 (Systemic Lupus Erythematosus and Other Specified Systemic Connective Tissue Disorders) under the V28 model, adding a risk factor of about 0.268 for a community, non-dual, aged beneficiary in payment year 2027.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
M06.4 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 leukopenia
- Idiopathic polyarthritis
- Immune dysregulation, inflammatory bowel disease, arthritis, recurrent infection, lymphopenia syndrome
- Inflammatory polyarthropathy
- Lymphocyte count below reference range
- Lymphocytopenia
- Pyoderma gangrenosum due to inflammatory polyarthropathy
- Undifferentiated inflammatory arthritis
- Undifferentiated inflammatory polyarthritis
Instructional NotesGuidance
Instructions from the official ICD-10-CM Tabular List that apply to M06.4: its own notes plus those printed at block M00-M25 and Chapter 13. 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.
- Disorders affecting predominantly peripheral (limb) joints
Excludes1
Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.
- polyarthritis NOS (M13.0)
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.
- arthropathic psoriasis (L40.5-)
- certain conditions originating in the perinatal period (P04-P96)
- certain infectious and parasitic diseases (A00-B99)
- compartment syndrome (traumatic) (T79.A-)
- complications of pregnancy, childbirth and the puerperium (O00-O9A)
- congenital malformations, deformations, and chromosomal abnormalities (Q00-Q99)
- endocrine, nutritional and metabolic diseases (E00-E88)
- 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)
Notes
General instructions on how these codes are used.
- Use an external cause code following the code for the musculoskeletal condition, if applicable, to identify the cause of the musculoskeletal condition
Source: CMS ICD-10-CM Tabular List. How to read instructional notes.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Polyarthritis, polyarthropathy See Also: Arthritis; M13.0
inflammatory M06.4
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Clinical InformationClinical
Inflammatory Polyarthropathy
pain and inflammation in more than five joints.
Patient EducationClinical
Arthritis
If you feel pain and stiffness in your body or have trouble moving around, you might have arthritis. Any disorder that affects the joints is often called arthritis. Joints are places where two bones meet, such as your elbow or knee.
The full article covers:
- What is arthritis?
- What are the types of arthritis?
- What are the symptoms of arthritis?
- Who is more likely to get arthritis?
- How is arthritis diagnosed?
- What are the treatments for arthritis?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert M06.4 to ICD-9-CMHistory
Code HistoryHistory
Questions About M06.4Overview
What is the ICD-10 code for inflammatory polyarthropathy?
The ICD-10-CM code for inflammatory polyarthropathy is M06.4 (sometimes written as M064). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
Is M06.4 (Other rheumatoid arthritis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report inflammatory polyarthropathy on HIPAA-covered claims from October 1, 2026 through September 30, 2027.
What MS-DRG does M06.4 group to?
When inflammatory polyarthropathy is the principal diagnosis on an inpatient stay, it groups to MS-DRG 554, 553, with relative weights from 0.8328 to 1.2492 depending on complications. Higher weights mean higher Medicare reimbursement.
Can M06.4 be reported with M13.0?
Not as a rule. The Excludes1 note on M06.4 lists "polyarthritis NOS (M13.0)". 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 is the ICD-9 equivalent of M06.4?
Under the General Equivalence Mappings, inflammatory polyarthropathy converts to ICD-9-CM 714.89 (inflamm polyarthrop NEC) and 714.9 (inflamm polyarthrop NOS). The mapping is approximate, so confirm the match fits the documentation.
What HCC is M06.4?
M06.4 (inflammatory polyarthropathy) maps to CMS-HCC Category 94 (Systemic Lupus Erythematosus and Other Specified Systemic Connective Tissue Disorders), commonly written as HCC 94, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2027. It mapped to HCC 40 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 83.
Does M06.4 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, M06.4 adds a risk adjustment factor of about 0.268 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.196 to 0.297 depending on the payment segment). A more severe related category (HCC 93) supersedes it when both are reported. See the full factor table on the HCC 94 category page.
