2026 ICD-10-CM Diagnosis Code M05.429Rheumatoid myopathy with rheumatoid arthritis of unspecified elbow
ICD-10-CM Codes›M00–M99›M05-M14›M05
- Billable — Valid for Submission
- CC — Complication or Comorbidity
- Risk Adjusts — HCC 93
- Chronic Condition
M05.429 is a billable ICD-10-CM diagnosis code for rheumatoid myopathy with rheumatoid arthritis of unspecified elbow. 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. 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 112 closely related codes. The code is flagged as an unspecified code, since codes identifying laterality exist in the same family. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Myopathies and Rheumatoid arthritis and related disease.
For Medicare Advantage risk adjustment, M05.429 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 M05.429.
Medicare Risk Adjustment (HCC)Billing
M05.429 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.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Rheumatoid Arthritis
Rheumatoid arthritis (RA) is a form of arthritis that causes pain, swelling, and stiffness in your joints. RA is an autoimmune disease. Although it is most common in the wrist and fingers, this disease can cause your immune system to attack any joint tissue. The inflammation (swelling) that comes with RA can also affect other body parts.
The full article covers:
- What is rheumatoid arthritis?
- Who is more likely to get rheumatoid arthritis?
- What causes rheumatoid arthritis?
- What are the symptoms of rheumatoid arthritis?
- How is rheumatoid arthritis diagnosed?
- What are the treatments for rheumatoid arthritis?
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert M05.429 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About M05.429Overview
What is the ICD-10 code for rheumatoid myopathy with rheumatoid arthritis of unspecified elbow?
The ICD-10-CM code for rheumatoid myopathy with rheumatoid arthritis of unspecified elbow is M05.429 (sometimes written as M05429). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is M05.429 (Rheumatoid myopathy with rheumatoid arthritis of elbow) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report rheumatoid myopathy with rheumatoid arthritis of unspecified elbow on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does M05.429 group to?
When rheumatoid myopathy with rheumatoid arthritis of unspecified elbow 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.
Is M05.429 a CC or MCC?
CMS lists M05.429 as a CC (complication or comorbidity) for FY 2026. 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 112 closely related codes in its exclusion list.
What is the ICD-9 equivalent of M05.429?
Under the General Equivalence Mappings, rheumatoid myopathy with rheumatoid arthritis of unspecified elbow converts to ICD-9-CM 714.0 (rheumatoid arthritis) and 359.6 (infl myopathy in oth dis). The mapping is approximate, so confirm the match fits the documentation.
What HCC is M05.429?
M05.429 (rheumatoid myopathy with rheumatoid arthritis of unspecified elbow) 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 M05.429 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, M05.429 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.
