2026 ICD-10-CM Diagnosis Code M08.9AJuvenile arthritis, unspecified, other specified site
ICD-10-CM Codes›M00–M99›M05-M14›M08
- Billable — Valid for Submission
- Risk Adjusts — HCC 93
- Chronic Condition
M08.9A is a billable ICD-10-CM diagnosis code for juvenile arthritis, unspecified, other specified site. 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. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Juvenile arthritis.
For Medicare Advantage risk adjustment, M08.9A 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
Medicare Risk Adjustment (HCC)Billing
M08.9A 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.
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.
Code History & ChangesHistory
Replacement M08.9A replaces the following previously assigned code(s):
- M08.90 - Juvenile arthritis, unspecified, unspecified site
Questions About M08.9AOverview
What is the ICD-10 code for juvenile arthritis, unspecified, other specified site?
The ICD-10-CM code for juvenile arthritis, unspecified, other specified site is M08.9A (sometimes written as M089A). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is M08.9A (Juvenile arthritis, unspecified) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report juvenile arthritis, unspecified, other specified site on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does M08.9A group to?
When juvenile arthritis, unspecified, other specified site 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.
What HCC is M08.9A?
M08.9A (juvenile arthritis, unspecified, other specified site) 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 M08.9A risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, M08.9A 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.
