M05.721
BillableRheumatoid arthritis with rheumatoid factor of right elbow without organ or systems involvement
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is M05.721 an HCC code?
Yes. M05.721 maps to Rheumatoid Arthritis and Inflammatory Connective Tissue Disease under the CMS-HCC V28 risk adjustment model (and Rheumatoid Arthritis and Inflammatory Connective Tissue Disease under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for M05.721
For M05.721to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed M05.721 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
M05.721 is the ICD-10-CM diagnosis code for rheumatoid arthritis with rheumatoid factor of right elbow without organ or systems involvement. Rheumatoid arthritis with positive rheumatoid factor affecting the right elbow only, without involvement of other organs or systems. M05.721 sits in the ICD-10-CM chapter for diseases of the musculoskeletal system and connective tissue (m00-m99), within the section covering inflammatory polyarthropathies (m05-m14).
Under the CMS-HCC V28 risk adjustment model, M05.721 maps to Rheumatoid Arthritis and Inflammatory Connective Tissue Disease (HCC 93) with a community, non-dual, aged base RAF weight of 0.175. Under the older V24 model, M05.721 mapped to the same category but with a base RAF weight of 0.307 — V28 recalibrated weights across the entire model. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
Confirm right elbow involvement in documentation; this code is specific to the right side. Because M05.721 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for M05.721 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Confirm right elbow involvement in documentation; this code is specific to the right side
- •Do not use this code for bilateral or left-sided elbow involvement
Clinical Significance
This code represents seropositive rheumatoid arthritis affecting the right elbow without systemic involvement, indicating localized inflammatory arthritis with confirmed positive rheumatoid factor. Despite being non-systemic, this represents significant chronic inflammatory disease requiring ongoing management and monitoring.
Documentation Requirements
- ✓Confirmation of rheumatoid arthritis diagnosis in right elbow joint
- ✓Documented positive rheumatoid factor laboratory test
- ✓Confirmation that no organ or system involvement is present
- ✓Clinical evidence of inflammatory arthritis specifically affecting right elbow
- ✓Exclusion of extra-articular manifestations
- ✓Documentation of disease activity and functional assessment
- ✓Clear identification of right elbow laterality
Commonly Confused Codes
- •M05721 vs M05722 — Wrong laterality (left vs right elbow)
- •M05721 vs M19.021 — M19.021 is primary osteoarthritis of right elbow
- •M05721 vs M25.521 — M25.521 is pain in right elbow without inflammation
- •M05721 vs M77.11 — M77.11 is lateral epicondylitis of right elbow
- •M05721 vs M05.621 — M05.621 includes organ involvement