2026 ICD-10-CM Diagnosis Code M06.1Adult-onset Still's disease
ICD-10-CM Codes›M00–M99›M05-M14›M06
- Billable — Valid for Submission
- Risk Adjusts — HCC 93
- Chronic Condition
M06.1 is a billable ICD-10-CM diagnosis code for adult-onset Still's disease. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 545 through 547. The code is restricted by the Medicare Code Editor to adult patients (age 15 through 124). Coders also document this condition as adult onset Still's disease. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Rheumatoid arthritis and related disease.
For Medicare Advantage risk adjustment, M06.1 maps to CMS-HCC Category 93 (Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders) under the V28 model, adding a risk factor of about 0.617 for a community, non-dual, aged beneficiary in payment year 2026.
Code Identity
Code Classification
Code EditsBilling
Medicare Code Editor checks that affect claim validity for M06.1.
Medicare Risk Adjustment (HCC)Billing
M06.1 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 2026.
Source: CMS Payment Year 2026 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.
- Adult onset Still's disease
- Complex multigenic autoinflammatory syndrome
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Type 1 Excludes
- Still's disease NOS M08.2
A type 1 excludes note is a pure excludes note. It means "NOT CODED HERE!" An Excludes1 note indicates that the code excluded should never be used at the same time as the code above the Excludes1 note. An Excludes1 is used when two conditions cannot occur together, such as a congenital form versus an acquired form of the same condition.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Juvenile Arthritis
Juvenile arthritis (JA) is arthritis that happens in children. It causes joint inflammation (swelling), pain, stiffness, and loss of motion. Joints are places where two bones meet, such as your elbow or knee. It can affect any joint, but it is more common in the knees, hands, and feet.
The full article covers:
- What is juvenile arthritis?
- Who is more likely to get juvenile arthritis?
- What causes juvenile arthritis?
- What are the symptoms of juvenile arthritis?
- How is juvenile arthritis diagnosed?
- What are the treatments for juvenile arthritis?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert M06.1 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About M06.1Overview
What is the ICD-10 code for adult-onset Still's disease?
The ICD-10-CM code for adult-onset Still's disease is M06.1 (sometimes written as M061). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is M06.1 (Other rheumatoid arthritis) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report adult-onset Still's disease on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does M06.1 group to?
When adult-onset Still's disease is the principal diagnosis on an inpatient stay, it groups to MS-DRG 545, 546, 547, with relative weights from 0.8362 to 2.4817 depending on complications. Higher weights mean higher Medicare reimbursement.
Who can M06.1 be reported for?
The Medicare Code Editor checks adult-onset Still's disease against patient demographics: this code is intended for adult patients (age 15 through 124). Claims outside these limits are flagged as inconsistent.
What is the ICD-9 equivalent of M06.1?
Under the General Equivalence Mappings, adult-onset Still's disease converts to ICD-9-CM 714.2 (syst rheum arthritis NEC). The mapping is approximate, so confirm the match fits the documentation.
What HCC is M06.1?
M06.1 (adult-onset Still's disease) maps to CMS-HCC Category 93 (Rheumatoid Arthritis and Other Specified Inflammatory Rheumatic Disorders), commonly written as HCC 93, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. 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 M06.1 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, M06.1 adds a risk adjustment factor of about 0.617 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.288 to 0.617 depending on the payment segment). HCC 93 sits at the top of its hierarchy, so no other condition category supersedes it. See the full factor table on the HCC 93 category page.
